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index 993b4c2b..a702b77f 100644
--- a/publication/ver11/5-rec/Overview.html
+++ b/publication/ver11/5-rec/Overview.html
@@ -148,7 +148,7 @@
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   "inLanguage": "en-US",
   "license": "https://www.w3.org/copyright/software-license-2023/",
-  "datePublished": "2023-11-30",
+  "datePublished": "2023-12-05",
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     "name": "World Wide Web Consortium",
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@@ -1126,7 +1126,7 @@
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   "group": "wg/wot",
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+  "publishDate": "2023-12-05",
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@@ -1451,8 +1451,8 @@
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     }
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@@ -1468,7 +1468,7 @@ <h1 id="title" class="title">Web of Things (WoT) Architecture
     1.1</h1>
     <p id="w3c-state"><a href=
     "https://www.w3.org/standards/types#REC">W3C Recommendation</a>
-    <time class="dt-published" datetime="2023-11-30">30 November
+    <time class="dt-published" datetime="2023-12-05">05 December
     2023</time></p>
     <details open="">
       <summary>
@@ -1478,8 +1478,8 @@ <h1 id="title" class="title">Web of Things (WoT) Architecture
         <dt>This version:</dt>
         <dd>
           <a class="u-url" href=
-          "https://www.w3.org/TR/2023/REC-wot-architecture11-20231130/">
-          https://www.w3.org/TR/2023/REC-wot-architecture11-20231130/</a>
+          "https://www.w3.org/TR/2023/REC-wot-architecture11-20231205/">
+          https://www.w3.org/TR/2023/REC-wot-architecture11-20231205/</a>
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         <dt>Latest published version:</dt>
         <dd>
@@ -10066,7 +10066,7 @@ <h3 id="c-1-normative-references"><bdi class=
           <a href="https://www.w3.org/TR/wot-discovery/"><cite>Web
           of Things (WoT) Discovery</cite></a>. Andrea Cimmino;
           Michael McCool; Farshid Tavakolizadeh; Kunihiko Toumura.
-          W3C. 30 November 2023. URL: <a href=
+          W3C. 5 December 2023. W3C Recommendation. URL: <a href=
           "https://www.w3.org/TR/wot-discovery/">https://www.w3.org/TR/wot-discovery/</a>
         </dd>
         <dt id="bib-wot-profile">[WOT-PROFILE]</dt>
@@ -10084,8 +10084,8 @@ <h3 id="c-1-normative-references"><bdi class=
           <a href=
           "https://www.w3.org/TR/wot-thing-description11/"><cite>Web
           of Things (WoT) Thing Description 1.1</cite></a>.
-          Sebastian Kaebisch; Michael McCool; Ege Korkan. W3C. 30
-          November 2023. URL: <a href=
+          Sebastian Kaebisch; Takuki Kamiya; Michael McCool; Victor
+          Charpenay. W3C. 5 December 2023. W3C Recommendation. URL: <a href=
           "https://www.w3.org/TR/wot-thing-description11/">https://www.w3.org/TR/wot-thing-description11/</a>
         </dd>
         <dt id="bib-wot-use-cases-requirements">
@@ -13991,7 +13991,7 @@ <h3 id="c-2-informative-references"><bdi class=
   panel.classList.remove("docked");
   }
   })()
-  </script> 
+  </script>
   <script src=
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diff --git a/publication/ver11/5-rec/diff.html b/publication/ver11/5-rec/diff.html
index a1e6b908..03a59a2f 100644
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+++ b/publication/ver11/5-rec/diff.html
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+  "datePublished": "2023-12-05",
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@@ -1144,7 +1144,7 @@
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@@ -1521,9 +1521,9 @@ <h1 id="title" class="title">
 <del class="diff-old">11
 July
 </del>
-<time class="dt-published" datetime="2023-11-30">
-<ins class="diff-chg">30
-November
+<time class="dt-published" datetime="2023-12-05">
+<ins class="diff-chg">05
+December
 </ins>
 2023
 </time>
@@ -1544,8 +1544,8 @@ <h1 id="title" class="title">
 <dd>
 <del class="diff-old">https://www.w3.org/TR/2023/PR-wot-architecture11-20230711/
 </del>
-<a class="u-url" href= "https://www.w3.org/TR/2023/REC-wot-architecture11-20231130/">
-<ins class="diff-chg">https://www.w3.org/TR/2023/REC-wot-architecture11-20231130/
+<a class="u-url" href= "https://www.w3.org/TR/2023/REC-wot-architecture11-20231205/">
+<ins class="diff-chg">https://www.w3.org/TR/2023/REC-wot-architecture11-20231205/
 </ins>
 </a>
 </dd>
@@ -35573,12 +35573,14 @@ <h3 id="c-1-normative-references">
 Kunihiko
 Toumura.
 W3C.
-<ins class="diff-new">30
-</ins>
-November
-<del class="diff-old">2020.
+<del class="diff-old">November
+2020.
 </del>
-<ins class="diff-chg">2023.
+<ins class="diff-chg">5
+December
+2023.
+W3C
+Recommendation.
 </ins>
 URL:
 <a href= "https://www.w3.org/TR/wot-discovery/">
@@ -35639,24 +35641,21 @@ <h3 id="c-1-normative-references">
 </a>.
 Sebastian
 Kaebisch;
-<del class="diff-old">Takuki
+Takuki
 Kamiya;
-</del>
 Michael
 McCool;
-<del class="diff-old">Victor
+Victor
 Charpenay.
-</del>
-<ins class="diff-chg">Ege
-Korkan.
-</ins>
 W3C.
-<ins class="diff-new">30
-</ins>
-November
-<del class="diff-old">2020.
+<del class="diff-old">November
+2020.
 </del>
-<ins class="diff-chg">2023.
+<ins class="diff-chg">5
+December
+2023.
+W3C
+Recommendation.
 </ins>
 URL:
 <a href= "https://www.w3.org/TR/wot-thing-description11/">
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+        "Vlad Trifa",
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+      ],
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+      "href": "https://www.w3.org/TR/wot-discovery/",
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+        "Andrea Cimmino",
+        "Michael McCool",
+        "Farshid Tavakolizadeh",
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+      "id": "wot-discovery"
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+      "href": "https://www.w3.org/TR/wot-security/",
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+        "Elena Reshetova"
+      ],
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+</head>
+<body class="h-entry toc-inline">
+<div class="head">
+<p class="logos">
+<a class="logo" href= "https://www.w3.org/">
+<img crossorigin="" alt="W3C" height="48" src="https://www.w3.org/StyleSheets/TR/2021/logos/W3C" width= "72" />
+</a>
+</p>
+<h1 id="title" class="title">
+Web
+of
+Things
+(WoT)
+Architecture
+1.1
+</h1>
+<p id="w3c-state">
+<a href= "https://www.w3.org/standards/types#REC">
+W3C
+Recommendation
+</a>
+<del class="diff-old">30
+November
+</del>
+<time class="dt-published" datetime="2023-12-05">
+<ins class="diff-chg">05
+December
+</ins>
+2023
+</time>
+</p>
+<details open="">
+<summary>
+More
+details
+about
+this
+document
+</summary>
+<dl>
+<dt>
+This
+version:
+</dt>
+<dd>
+<del class="diff-old">https://www.w3.org/TR/2023/REC-wot-architecture11-20231130/
+</del>
+<a class="u-url" href= "https://www.w3.org/TR/2023/REC-wot-architecture11-20231205/">
+<ins class="diff-chg">https://www.w3.org/TR/2023/REC-wot-architecture11-20231205/
+</ins>
+</a>
+</dd>
+<dt>
+Latest
+published
+version:
+</dt>
+<dd>
+<a href= "https://www.w3.org/TR/wot-architecture11/">
+https://www.w3.org/TR/wot-architecture11/
+</a>
+</dd>
+<dt>
+Latest
+editor's
+draft:
+</dt>
+<dd>
+<a href= "https://w3c.github.io/wot-architecture/">
+https://w3c.github.io/wot-architecture/
+</a>
+</dd>
+<dt>
+History:
+</dt>
+<dd>
+<a href= "https://www.w3.org/standards/history/wot-architecture11/">
+https://www.w3.org/standards/history/wot-architecture11/
+</a>
+</dd>
+<dd>
+<a href= "https://github.com/w3c/wot-architecture/commits/main">
+Commit
+history
+</a>
+</dd>
+<dt>
+Implementation
+report:
+</dt>
+<dd>
+<a href= "https://w3c.github.io/wot-architecture/testing/report11.html">
+https://w3c.github.io/wot-architecture/testing/report11.html
+</a>
+</dd>
+<dt>
+Editors:
+</dt>
+<dd class="editor p-author h-card vcard" data-editor-id="47166">
+<span class="p-name fn">
+Michael
+Lagally
+</span>
+(
+<a class= "p-org org h-org" href="https://www.oracle.com/">
+Oracle
+Corp.
+</a>
+)
+</dd>
+<dd class="editor p-author h-card vcard" data-editor-id="64284">
+<span class="p-name fn">
+Ryuichi
+Matsukura
+</span>
+(
+<a class= "p-org org h-org" href="https://www.fujitsu.com/">
+Fujitsu
+Ltd.
+</a>
+)
+</dd>
+<dd class="editor p-author h-card vcard" data-editor-id="93137">
+<span class="p-name fn">
+Michael
+McCool
+</span>
+(
+<a class= "p-org org h-org" href="https://www.intel.com/">
+Intel
+Corp.
+</a>
+)
+</dd>
+<dd class="editor p-author h-card vcard" data-editor-id="83488">
+<span class="p-name fn">
+Kunihiko
+Toumura
+</span>
+(
+<a class= "p-org org h-org" href="https://www.hitachi.com/">
+Hitachi,
+Ltd.
+</a>
+)
+</dd>
+<dt>
+Former
+editors:
+</dt>
+<dd class="editor p-author h-card vcard">
+<span class= "p-name fn">
+Kazuo
+Kajimoto
+</span>
+(when
+at
+Panasonic
+Corp.)
+</dd>
+<dd class="editor p-author h-card vcard" data-editor-id="79307">
+<span class="p-name fn">
+Toru
+Kawaguchi
+</span>
+(
+<a class= "p-org org h-org" href="https://www.panasonic.com/">
+Panasonic
+Corp.
+</a>
+)
+</dd>
+<dd class="editor p-author h-card vcard">
+<span class= "p-name fn">
+Matthias
+Kovatsch
+</span>
+(
+<a class="p-org org h-org" href="https://www.huawei.com">
+Huawei
+</a>
+)
+</dd>
+<dt>
+Feedback:
+</dt>
+<dd>
+<a href="https://github.com/w3c/wot-architecture/">
+GitHub
+w3c/wot-architecture
+</a>
+(
+<a href= "https://github.com/w3c/wot-architecture/pulls/">
+pull
+requests
+</a>,
+<a href= "https://github.com/w3c/wot-architecture/issues/new/choose">
+new
+issue
+</a>,
+<a href= "https://github.com/w3c/wot-architecture/issues/">
+open
+issues
+</a>
+)
+</dd>
+<dd>
+<a href= "mailto:public-wot-wg@w3.org?subject=%5Bwot-architecture11%5D%20YOUR%20TOPIC%20HERE">
+public-wot-wg@w3.org
+</a>
+with
+subject
+line
+<kbd>
+[wot-architecture11]
+<em>
+…
+message
+topic
+…
+</em>
+</kbd>
+(
+<a rel= "discussion" href= "https://lists.w3.org/Archives/Public/public-wot-wg">
+archives
+</a>
+)
+</dd>
+<dt>
+Errata:
+</dt>
+<dd>
+<a href= "https://w3c.github.io/wot-architecture/errata11.html">
+Errata
+exists
+</a>.
+</dd>
+<dt>
+Previous
+Recommendation
+</dt>
+<dd>
+<a href= "https://www.w3.org/TR/2020/REC-wot-architecture-20200409/">
+https://www.w3.org/TR/2020/REC-wot-architecture-20200409/
+</a>
+</dd>
+<dt>
+Contributors
+</dt>
+<dd>
+<a href= "https://github.com/w3c/wot-architecture/graphs/contributors">
+In
+the
+GitHub
+repository
+</a>
+</dd>
+<dt>
+Repository
+</dt>
+<dd>
+<a href="https://github.com/w3c/wot-architecture/">
+We
+are
+on
+GitHub
+</a>
+</dd>
+<dd>
+<a href="https://github.com/w3c/wot-architecture/issues">
+File
+a
+bug
+</a>
+</dd>
+</dl>
+</details>
+<p>
+See
+also
+<a href= "https://www.w3.org/Translations/?technology=wot-architecture11">
+<strong>
+translations
+</strong>
+</a>.
+</p>
+<p class="copyright">
+<a href= "https://www.w3.org/policies/#copyright">
+Copyright
+</a>
+©
+2017-2023
+<a href="https://www.w3.org/">
+World
+Wide
+Web
+Consortium
+</a>.
+<abbr title="World Wide Web Consortium">
+W3C
+</abbr>
+<sup>
+®
+</sup>
+<a href= "https://www.w3.org/policies/#Legal_Disclaimer">
+liability
+</a>,
+<a href="https://www.w3.org/policies/#W3C_Trademarks">
+trademark
+</a>
+and
+<a rel="license" href= "https://www.w3.org/copyright/software-license-2023/" title= "W3C Software and Document Notice and License">
+permissive
+document
+license
+</a>
+rules
+apply.
+</p>
+<hr title="Separator for header" />
+</div>
+<section id="abstract" class="introductory">
+<h2>
+Abstract
+</h2>
+<p>
+The
+<abbr title="World Wide Web Consortium">
+W3C
+</abbr>
+Web
+of
+Things
+(WoT)
+enables
+interoperability
+across
+IoT
+platforms
+and
+application
+domains.
+The
+goal
+of
+the
+WoT
+is
+to
+preserve
+and
+complement
+existing
+IoT
+standards
+and
+solutions.
+The
+<abbr title= "World Wide Web Consortium">
+W3C
+</abbr>
+WoT
+architecture
+is
+designed
+to
+describe
+what
+exists,
+and
+only
+prescribes
+new
+mechanisms
+when
+necessary.
+</p>
+<p>
+This
+<em>
+WoT
+Architecture
+</em>
+specification
+describes
+the
+abstract
+architecture
+for
+the
+<abbr title= "World Wide Web Consortium">
+W3C
+</abbr>
+Web
+of
+Things.
+This
+abstract
+architecture
+is
+based
+on
+requirements
+that
+were
+derived
+from
+use
+cases
+for
+multiple
+application
+domains.
+Several
+modular
+building
+blocks
+were
+identified
+whose
+detailed
+specifications
+are
+given
+in
+other
+documents.
+This
+document
+describes
+how
+these
+building
+blocks
+are
+related
+and
+work
+together.
+The
+WoT
+abstract
+architecture
+defines
+a
+basic
+conceptual
+framework
+that
+can
+be
+mapped
+onto
+a
+variety
+of
+concrete
+deployment
+scenarios,
+several
+examples
+of
+which
+are
+given.
+However,
+the
+abstract
+architecture
+described
+in
+this
+specification
+does
+not
+itself
+define
+concrete
+mechanisms
+or
+prescribe
+any
+concrete
+implementation.
+</p>
+</section>
+<section id="sotd" class="introductory">
+<h2>
+Status
+of
+This
+Document
+</h2>
+<p>
+<em>
+This
+section
+describes
+the
+status
+of
+this
+document
+at
+the
+time
+of
+its
+publication.
+A
+list
+of
+current
+<abbr title= "World Wide Web Consortium">
+W3C
+</abbr>
+publications
+and
+the
+latest
+revision
+of
+this
+technical
+report
+can
+be
+found
+in
+the
+<a href= "https://www.w3.org/TR/">
+<abbr title= "World Wide Web Consortium">
+W3C
+</abbr>
+technical
+reports
+index
+</a>
+at
+https://www.w3.org/TR/.
+</em>
+</p>
+<p>
+This
+document
+describes
+an
+abstract
+architecture.
+However,
+there
+is
+an
+<a href= "https://w3c.github.io/wot-architecture/testing/report11.html">
+Implementation
+Report
+</a>
+that
+describes
+a
+set
+of
+concrete
+implementations
+following
+the
+<abbr title="World Wide Web Consortium">
+W3C
+</abbr>
+Web
+of
+Things
+architecture.
+It
+also
+references
+the
+other
+implementation
+reports
+for
+the
+various
+WoT
+building
+blocks.
+</p>
+<p>
+Future
+updates
+to
+this
+specification
+may
+incorporate
+<a href= "https://www.w3.org/2021/Process-20211102/#allow-new-features">
+new
+features
+</a>.
+</p>
+<p>
+This
+document
+was
+published
+by
+the
+<a href= "https://www.w3.org/groups/wg/wot">
+Web
+of
+Things
+Working
+Group
+</a>
+as
+a
+Recommendation
+using
+the
+<a href= "https://www.w3.org/2023/Process-20231103/#recs-and-notes">
+Recommendation
+track
+</a>.
+</p>
+<p>
+<abbr title="World Wide Web Consortium">
+W3C
+</abbr>
+recommends
+the
+wide
+deployment
+of
+this
+specification
+as
+a
+standard
+for
+the
+Web.
+</p>
+<p>
+A
+<abbr title="World Wide Web Consortium">
+W3C
+</abbr>
+Recommendation
+is
+a
+specification
+that,
+after
+extensive
+consensus-building,
+is
+endorsed
+by
+<abbr title= "World Wide Web Consortium">
+W3C
+</abbr>
+and
+its
+Members,
+and
+has
+commitments
+from
+Working
+Group
+members
+to
+<a href= "https://www.w3.org/Consortium/Patent-Policy/#sec-Requirements">
+royalty-free
+licensing
+</a>
+for
+implementations.
+</p>
+<p>
+This
+document
+was
+produced
+by
+a
+group
+operating
+under
+the
+<a href="https://www.w3.org/Consortium/Patent-Policy/">
+<abbr title= "World Wide Web Consortium">
+W3C
+</abbr>
+Patent
+Policy
+</a>.
+<abbr title="World Wide Web Consortium">
+W3C
+</abbr>
+maintains
+a
+<a rel="disclosure" href= "https://www.w3.org/groups/wg/wot/ipr">
+public
+list
+of
+any
+patent
+disclosures
+</a>
+made
+in
+connection
+with
+the
+deliverables
+of
+the
+group;
+that
+page
+also
+includes
+instructions
+for
+disclosing
+a
+patent.
+An
+individual
+who
+has
+actual
+knowledge
+of
+a
+patent
+which
+the
+individual
+believes
+contains
+<a href= "https://www.w3.org/Consortium/Patent-Policy/#def-essential">
+Essential
+Claim(s)
+</a>
+must
+disclose
+the
+information
+in
+accordance
+with
+<a href= "https://www.w3.org/Consortium/Patent-Policy/#sec-Disclosure">
+section
+6
+of
+the
+<abbr title="World Wide Web Consortium">
+W3C
+</abbr>
+Patent
+Policy
+</a>.
+</p>
+<p>
+This
+document
+is
+governed
+by
+the
+<a id="w3c_process_revision" href="https://www.w3.org/2023/Process-20231103/">
+03
+November
+2023
+<abbr title="World Wide Web Consortium">
+W3C
+</abbr>
+Process
+Document
+</a>.
+</p>
+</section>
+<nav id="toc">
+<h2 class="introductory" id="table-of-contents">
+Table
+of
+Contents
+</h2>
+<ol class="toc">
+<li class="tocline">
+<a class="tocxref" href= "#abstract">
+Abstract
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href="#sotd">
+Status
+of
+This
+Document
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#introduction">
+<bdi class="secno">
+1.
+</bdi>
+Introduction
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#conformance">
+<bdi class="secno">
+2.
+</bdi>
+Conformance
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#terminology">
+<bdi class="secno">
+3.
+</bdi>
+Terminology
+</a>
+<ol class="toc">
+<li class="tocline">
+<a class="tocxref" href= "#device-categories">
+<bdi class="secno">
+3.1
+</bdi>
+Device
+Categories
+</a>
+</li>
+</ol>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-application-domains">
+<bdi class="secno">
+4.
+</bdi>
+Application
+Domains
+</a>
+<ol class="toc">
+<li class="tocline">
+<a class="tocxref" href= "#consumer-use-cases">
+<bdi class="secno">
+4.1
+</bdi>
+Consumer
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#industrial-iot-usecases">
+<bdi class="secno">
+4.2
+</bdi>
+Industrial
+</a>
+<ol class="toc">
+<li class="tocline">
+<a class="tocxref" href= "#example-smart-factory">
+<bdi class="secno">
+4.2.1
+</bdi>
+Example:
+Smart
+Factory
+</a>
+</li>
+</ol>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#transportationlogistics">
+<bdi class="secno">
+4.3
+</bdi>
+Transportation
+&amp;
+Logistics
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#utilities">
+<bdi class="secno">
+4.4
+</bdi>
+Utilities
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#oilandgas">
+<bdi class="secno">
+4.5
+</bdi>
+Oil
+and
+Gas
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#insurance">
+<bdi class="secno">
+4.6
+</bdi>
+Insurance
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#engineering-and-construction">
+<bdi class="secno">
+4.7
+</bdi>
+Engineering
+and
+Construction
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#agriculture">
+<bdi class="secno">
+4.8
+</bdi>
+Agriculture
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#healthcare">
+<bdi class="secno">
+4.9
+</bdi>
+Healthcare
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#environmentmonitoring">
+<bdi class="secno">
+4.10
+</bdi>
+Environment
+Monitoring
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#smartcities">
+<bdi class="secno">
+4.11
+</bdi>
+Smart
+Cities
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#smartbuildings">
+<bdi class="secno">
+4.12
+</bdi>
+Smart
+Buildings
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#connectedcar">
+<bdi class="secno">
+4.13
+</bdi>
+Connected
+Car
+</a>
+<ol class="toc">
+<li class="tocline">
+<a class="tocxref" href= "#connectedcar-example">
+<bdi class="secno">
+4.13.1
+</bdi>
+Connected
+Car
+Example
+</a>
+</li>
+</ol>
+</li>
+</ol>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-common-deployment-patterns">
+<bdi class="secno">
+5.
+</bdi>
+Common
+Deployment
+Patterns
+</a>
+<ol class="toc">
+<li class="tocline">
+<a class="tocxref" href= "#telemetry">
+<bdi class="secno">
+5.1
+</bdi>
+Telemetry
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#device-controllers">
+<bdi class="secno">
+5.2
+</bdi>
+Device
+Controllers
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#thing-to-thing">
+<bdi class="secno">
+5.3
+</bdi>
+Thing-to-Thing
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#remote-access">
+<bdi class="secno">
+5.4
+</bdi>
+Remote
+Access
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#smart-home-gateways">
+<bdi class="secno">
+5.5
+</bdi>
+Smart
+Home
+Gateways
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#edge-devices">
+<bdi class="secno">
+5.6
+</bdi>
+Edge
+Devices
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#digital-twins">
+<bdi class="secno">
+5.7
+</bdi>
+Digital
+Twins
+</a>
+<ol class="toc">
+<li class="tocline">
+<a class="tocxref" href= "#cloud-connected-devices">
+<bdi class="secno">
+5.7.1
+</bdi>
+Cloud
+Connected
+Devices
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#orchestration">
+<bdi class="secno">
+5.7.2
+</bdi>
+Orchestration
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#legacy-devices">
+<bdi class="secno">
+5.7.3
+</bdi>
+Legacy
+Devices
+</a>
+</li>
+</ol>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#multi-cloud">
+<bdi class="secno">
+5.8
+</bdi>
+Multi-Cloud
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#virtual-thing">
+<bdi class="secno">
+5.9
+</bdi>
+Virtual
+Things
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-cross-domain-collaboration">
+<bdi class="secno">
+5.10
+</bdi>
+Cross-domain
+Collaboration
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-system-integration">
+<bdi class="secno">
+5.11
+</bdi>
+System
+Integration
+</a>
+</li>
+</ol>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-wot-architecture">
+<bdi class="secno">
+6.
+</bdi>
+Abstract
+WoT
+System
+Architecture
+</a>
+<ol class="toc">
+<li class="tocline">
+<a class="tocxref" href= "#sec-architecture-overview">
+<bdi class="secno">
+6.1
+</bdi>
+Fundamental
+Concepts
+</a>
+<ol class="toc">
+<li class="tocline">
+<a class="tocxref" href="#metadata">
+<bdi class= "secno">
+6.1.1
+</bdi>
+Metadata
+</a>
+<ol class="toc">
+<li class="tocline">
+<a class="tocxref" href= "#metadata-thing-descriptions">
+<bdi class="secno">
+6.1.1.1
+</bdi>
+Thing
+Descriptions
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#metadata-thing-models">
+<bdi class="secno">
+6.1.1.2
+</bdi>
+Thing
+Models
+</a>
+</li>
+</ol>
+</li>
+<li class="tocline">
+<a class="tocxref" href="#links">
+<bdi class= "secno">
+6.1.2
+</bdi>
+Links
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#intermediaries">
+<bdi class="secno">
+6.1.3
+</bdi>
+Intermediaries
+</a>
+</li>
+</ol>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-affordances">
+<bdi class="secno">
+6.2
+</bdi>
+Affordances
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-web-thing">
+<bdi class="secno">
+6.3
+</bdi>
+Web
+Thing
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#lifecycle">
+<bdi class="secno">
+6.4
+</bdi>
+Lifecycle
+</a>
+<ol class="toc">
+<li class="tocline">
+<a class="tocxref" href= "#simple-system-lifecycle">
+<bdi class="secno">
+6.4.1
+</bdi>
+Simple
+System
+Lifecycle
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#system-lifecycle-no-directory">
+<bdi class="secno">
+6.4.2
+</bdi>
+System
+Lifecycle
+with
+Registration
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#thing-lifecycle">
+<bdi class="secno">
+6.4.3
+</bdi>
+Thing
+Lifecycle
+</a>
+</li>
+</ol>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-interaction-model">
+<bdi class="secno">
+6.5
+</bdi>
+Interaction
+Model
+</a>
+<ol class="toc">
+<li class="tocline">
+<a class="tocxref" href= "#properties">
+<bdi class="secno">
+6.5.1
+</bdi>
+Properties
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href="#actions">
+<bdi class= "secno">
+6.5.2
+</bdi>
+Actions
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href="#events">
+<bdi class= "secno">
+6.5.3
+</bdi>
+Events
+</a>
+</li>
+</ol>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-hypermedia-controls">
+<bdi class="secno">
+6.6
+</bdi>
+Hypermedia
+Controls
+</a>
+<ol class="toc">
+<li class="tocline">
+<a class="tocxref" href= "#sec-hypermedia-links">
+<bdi class="secno">
+6.6.1
+</bdi>
+Links
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-hypermedia-forms">
+<bdi class="secno">
+6.6.2
+</bdi>
+Forms
+</a>
+</li>
+</ol>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-protocol-bindings">
+<bdi class="secno">
+6.7
+</bdi>
+Protocol
+Bindings
+</a>
+<ol class="toc">
+<li class="tocline">
+<a class="tocxref" href= "#hypermedia-driven">
+<bdi class="secno">
+6.7.1
+</bdi>
+Hypermedia-driven
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-arch-URIs">
+<bdi class="secno">
+6.7.2
+</bdi>
+URIs
+</a>
+</li>
+</ol>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#media-types">
+<bdi class="secno">
+6.8
+</bdi>
+Media
+Types
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href="#sec-i18n">
+<bdi class= "secno">
+6.9
+</bdi>
+Internationalization
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-wot-servient-architecture-high-level">
+<bdi class= "secno">
+6.10
+</bdi>
+WoT
+System
+Components
+and
+their
+Interconnectivity
+</a>
+<ol class="toc">
+<li class="tocline">
+<a class="tocxref" href= "#direct-communication">
+<bdi class="secno">
+6.10.1
+</bdi>
+Direct
+Communication
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#indirect-communication">
+<bdi class="secno">
+6.10.2
+</bdi>
+Indirect
+Communication
+</a>
+</li>
+</ol>
+</li>
+</ol>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-building-blocks">
+<bdi class="secno">
+7.
+</bdi>
+WoT
+Building
+Blocks
+</a>
+<ol class="toc">
+<li class="tocline">
+<a class="tocxref" href= "#sec-thing-description">
+<bdi class="secno">
+7.1
+</bdi>
+WoT
+Thing
+Description
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-thing-model">
+<bdi class="secno">
+7.2
+</bdi>
+Thing
+Model
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#wot-profiles">
+<bdi class="secno">
+7.3
+</bdi>
+Profiles
+</a>
+<ol class="toc">
+<li class="tocline">
+<a class="tocxref" href= "#profile-description-methodology">
+<bdi class="secno">
+7.3.1
+</bdi>
+Profiling
+Methodology
+</a>
+</li>
+</ol>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-discovery">
+<bdi class="secno">
+7.4
+</bdi>
+WoT
+Discovery
+</a>
+<ol class="toc">
+<li class="tocline">
+<a class="tocxref" href= "#sec-discovery-introductions">
+<bdi class="secno">
+7.4.1
+</bdi>
+Introduction
+Mechanisms
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-discovery-exploration">
+<bdi class="secno">
+7.4.2
+</bdi>
+Exploration
+Mechanisms
+</a>
+</li>
+</ol>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-binding-templates">
+<bdi class="secno">
+7.5
+</bdi>
+WoT
+Binding
+Templates
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-scripting-api">
+<bdi class="secno">
+7.6
+</bdi>
+WoT
+Scripting
+API
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-security-guidelines">
+<bdi class="secno">
+7.7
+</bdi>
+WoT
+Security
+and
+Privacy
+Guidelines
+</a>
+</li>
+</ol>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-servient-implementation">
+<bdi class="secno">
+8.
+</bdi>
+Abstract
+Servient
+Architecture
+</a>
+<ol class="toc">
+<li class="tocline">
+<a class="tocxref" href= "#behavior-implementation">
+<bdi class="secno">
+8.1
+</bdi>
+Behavior
+Implementation
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#wot-runtime">
+<bdi class="secno">
+8.2
+</bdi>
+WoT
+Runtime
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#wot-scripting-api">
+<bdi class="secno">
+8.3
+</bdi>
+WoT
+Scripting
+API
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#expose-consumed-thing">
+<bdi class="secno">
+8.4
+</bdi>
+Exposed
+Thing
+and
+Consumed
+Thing
+Abstractions
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#private-security-data">
+<bdi class="secno">
+8.5
+</bdi>
+Private
+Security
+Data
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#protocol-stack-implementation">
+<bdi class="secno">
+8.6
+</bdi>
+Protocol
+Stack
+Implementation
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#system-api">
+<bdi class="secno">
+8.7
+</bdi>
+System
+API
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#alt-servient-impl">
+<bdi class="secno">
+8.8
+</bdi>
+Alternative
+Servient
+and
+WoT
+Implementations
+</a>
+<ol class="toc">
+<li class="tocline">
+<a class="tocxref" href= "#native-impl">
+<bdi class="secno">
+8.8.1
+</bdi>
+Native
+WoT
+API
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#existing-impl">
+<bdi class="secno">
+8.8.2
+</bdi>
+Thing
+Description
+for
+Existing
+Devices
+</a>
+</li>
+</ol>
+</li>
+</ol>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-deployment-scenario">
+<bdi class="secno">
+9.
+</bdi>
+Example
+WoT
+Deployments
+</a>
+<ol class="toc">
+<li class="tocline">
+<a class="tocxref" href= "#sec-client-server-roles">
+<bdi class="secno">
+9.1
+</bdi>
+Thing
+and
+Consumer
+Roles
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-topologies-deployment-scenarios">
+<bdi class="secno">
+9.2
+</bdi>
+Topology
+of
+WoT
+Systems
+and
+Deployment
+Scenarios
+</a>
+<ol class="toc">
+<li class="tocline">
+<a class="tocxref" href= "#sec-deployment-app-dev">
+<bdi class="secno">
+9.2.1
+</bdi>
+Consumer
+and
+Thing
+on
+the
+Same
+Network
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-deployment-intermediaries">
+<bdi class="secno">
+9.2.2
+</bdi>
+Consumer
+and
+Thing
+Connected
+via
+Intermediaries
+</a>
+<ol class="toc">
+<li class="tocline">
+<a class="tocxref" href= "#sec-deployment-app-proxy-dev">
+<bdi class="secno">
+9.2.2.1
+</bdi>
+Intermediary
+Acting
+as
+a
+Proxy
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-deployment-digital-twin">
+<bdi class="secno">
+9.2.2.2
+</bdi>
+Intermediary
+Acting
+as
+a
+Digital
+Twin
+</a>
+</li>
+</ol>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-deployment-cloud">
+<bdi class="secno">
+9.2.3
+</bdi>
+Devices
+in
+a
+Local
+Network
+Controlled
+from
+a
+Cloud
+Service
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-deployment-discovery-with-directory">
+<bdi class= "secno">
+9.2.4
+</bdi>
+Discovery
+Using
+a
+Thing
+Description
+Directory
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-deployment-service-to-service">
+<bdi class="secno">
+9.2.5
+</bdi>
+Service-to-Service
+Connections
+Across
+Multiple
+Domains
+</a>
+<ol class="toc">
+<li class="tocline">
+<a class="tocxref" href= "#sec-deployment-service-to-service-synchronized">
+<bdi class= "secno">
+9.2.5.1
+</bdi>
+Connection
+Through
+Thing
+Description
+Directory
+Synchronization
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-deployment-service-sync-proxy">
+<bdi class= "secno">
+9.2.5.2
+</bdi>
+Connection
+Through
+Proxy
+Synchronization
+</a>
+</li>
+</ol>
+</li>
+</ol>
+</li>
+</ol>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-security-considerations">
+<bdi class="secno">
+10.
+</bdi>
+Security
+Considerations
+</a>
+<ol class="toc">
+<li class="tocline">
+<a class="tocxref" href= "#sec-security-consideration-td-risks">
+<bdi class= "secno">
+10.1
+</bdi>
+WoT
+Thing
+Description
+Risks
+</a>
+<ol class="toc">
+<li class="tocline">
+<a class="tocxref" href= "#sec-security-consideration-td-private">
+<bdi class= "secno">
+10.1.1
+</bdi>
+Thing
+Description
+Private
+Security
+Data
+Risk
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-security-consideration-td-cm">
+<bdi class="secno">
+10.1.2
+</bdi>
+Thing
+Description
+Communication
+Metadata
+Risk
+</a>
+</li>
+</ol>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-security-consideration-scripting-risks">
+<bdi class= "secno">
+10.2
+</bdi>
+WoT
+Scripting
+API
+Risks
+</a>
+<ol class="toc">
+<li class="tocline">
+<a class="tocxref" href= "#sec-security-consideration-cross-script">
+<bdi class= "secno">
+10.2.1
+</bdi>
+Cross-Script
+Security
+Risk
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-security-consideration-device-direct-access">
+<bdi class= "secno">
+10.2.2
+</bdi>
+Physical
+Device
+Direct
+Access
+Risk
+</a>
+</li>
+</ol>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-security-consideration-runtime-risks">
+<bdi class= "secno">
+10.3
+</bdi>
+WoT
+Runtime
+Risks
+</a>
+<ol class="toc">
+<li class="tocline">
+<a class="tocxref" href= "#sec-security-consideration-update-provisioning">
+<bdi class= "secno">
+10.3.1
+</bdi>
+Provisioning
+and
+Update
+Security
+Risk
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-security-consideration-credentials-storage">
+<bdi class= "secno">
+10.3.2
+</bdi>
+Security
+Credentials
+Storage
+Risk
+</a>
+</li>
+</ol>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-security-consideration-trusted-environment-risks">
+<bdi class= "secno">
+10.4
+</bdi>
+Trusted
+Environment
+Risks
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-security-consideration-secure-transport">
+<bdi class= "secno">
+10.5
+</bdi>
+Secure
+Transport
+</a>
+</li>
+</ol>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-privacy-considerations">
+<bdi class="secno">
+11.
+</bdi>
+Privacy
+Considerations
+</a>
+<ol class="toc">
+<li class="tocline">
+<a class="tocxref" href= "#sec-privacy-consideration-td-risks">
+<bdi class="secno">
+11.1
+</bdi>
+WoT
+Thing
+Description
+Risks
+</a>
+<ol class="toc">
+<li class="tocline">
+<a class="tocxref" href= "#sec-privacy-consideration-td-pii">
+<bdi class="secno">
+11.1.1
+</bdi>
+Thing
+Description
+Personally
+Identifiable
+Information
+Risk
+</a>
+</li>
+</ol>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#arch-privacy-consideration-access-controls">
+<bdi class= "secno">
+11.2
+</bdi>
+Access
+to
+Personally
+Identifiable
+Information
+</a>
+</li>
+</ol>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-accessibility-considerations">
+<bdi class="secno">
+12.
+</bdi>
+Accessibility
+Considerations
+</a>
+<ol class="toc">
+<li class="tocline">
+<a class="tocxref" href= "#sec-accessibility-considerations-greenfield">
+<bdi class= "secno">
+12.1
+</bdi>
+Greenfield
+WoT
+Systems
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#sec-accessibility-considerations-brownfield">
+<bdi class= "secno">
+12.2
+</bdi>
+Brownfield
+WoT
+Systems
+</a>
+</li>
+</ol>
+</li>
+<li class="tocline">
+<a class="tocxref" href="#changes">
+<bdi class= "secno">
+A.
+</bdi>
+Recent
+Specification
+Changes
+</a>
+<ol class="toc">
+<li class="tocline">
+<a class="tocxref" href= "#changes-from-pr">
+<bdi class="secno">
+A.1
+</bdi>
+Changes
+from
+11
+July
+2023
+Proposed
+Recommendation
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#changes-from-cr">
+<bdi class="secno">
+A.2
+</bdi>
+Changes
+from
+19
+January
+2023
+Candidate
+Recommendation
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#changes-from-wd-2022-09-07">
+<bdi class="secno">
+A.3
+</bdi>
+Changes
+from
+the
+WD
+published
+September
+7,
+2022
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#changes-from-fpwd-1.1">
+<bdi class="secno">
+A.4
+</bdi>
+Changes
+in
+WD
+published
+September
+7,
+2022
+from
+the
+FPWD
+version
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#changes-in-fpwd-1.1-from-recommendation-1.0">
+<bdi class= "secno">
+A.5
+</bdi>
+Changes
+in
+the
+FPWD
+from
+the
+1.0
+version
+of
+[
+<cite>
+<span class="formerLink" data-link-type="biblio" title= "Web of Things (WoT) Architecture">
+wot-architecture
+</span>
+</cite>
+]
+</a>
+</li>
+</ol>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#acknowledgements">
+<bdi class="secno">
+B.
+</bdi>
+Acknowledgments
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#references">
+<bdi class="secno">
+C.
+</bdi>
+References
+</a>
+<ol class="toc">
+<li class="tocline">
+<a class="tocxref" href= "#normative-references">
+<bdi class="secno">
+C.1
+</bdi>
+Normative
+references
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href= "#informative-references">
+<bdi class="secno">
+C.2
+</bdi>
+Informative
+references
+</a>
+</li>
+</ol>
+</li>
+</ol>
+</nav>
+<section id="introduction" class="informative">
+<div class="header-wrapper">
+<h2 id="x1-introduction">
+<bdi class="secno">
+1.
+</bdi>
+Introduction
+</h2>
+<a class="self-link" href="#introduction" aria-label= "Permalink for Section 1.">
+</a>
+</div>
+<p>
+<em>
+This
+section
+is
+non-normative.
+</em>
+</p>
+<p>
+The
+goals
+of
+the
+<em>
+Web
+of
+Things
+</em>
+(WoT)
+are
+to
+improve
+the
+interoperability
+and
+usability
+of
+the
+Internet
+of
+Things
+(IoT).
+Through
+a
+collaboration
+involving
+many
+stakeholders
+over
+many
+years,
+several
+building
+blocks
+have
+been
+identified
+that
+help
+address
+these
+challenges.
+</p>
+<p>
+A
+set
+of
+over
+30
+WoT
+<em>
+use
+cases
+</em>
+were
+contributed
+by
+stakeholders
+from
+multiple
+industries
+for
+various
+application
+domains.
+These
+have
+been
+collected
+and
+were
+published
+in
+the
+<em>
+WoT
+Use
+Cases
+and
+Requirements
+</em>
+<a href= "https://www.w3.org/TR/wot-usecases/">
+https://www.w3.org/TR/wot-usecases/
+</a>
+document.
+</p>
+<p>
+The
+collection
+of
+use
+cases
+is
+classified
+into
+two
+categories:
+</p>
+<ul>
+<li>
+Horizontal
+use
+cases
+that
+address
+multiple
+domains
+</li>
+<li>
+Domain
+specific
+(vertical)
+use
+cases
+for
+a
+single
+application
+domain
+</li>
+</ul>
+<p>
+These
+use
+cases
+and
+requirements
+drive
+the
+creation
+and
+further
+evolution
+of
+the
+<abbr title="World Wide Web Consortium">
+W3C
+</abbr>
+WoT
+specification
+family.
+</p>
+<p>
+The
+WoT
+architecture
+specification
+is
+focused
+on
+the
+scope
+of
+<abbr title="World Wide Web Consortium">
+W3C
+</abbr>
+WoT
+standardization,
+which
+can
+be
+broken
+down
+into
+these
+building
+blocks
+as
+well
+as
+the
+abstract
+architecture
+that
+defines
+how
+they
+are
+related.
+</p>
+<p>
+The
+architecture
+document
+serves
+multiple
+purposes:
+</p>
+<p>
+The
+building
+blocks
+are
+defined
+and
+described
+in
+detail
+in
+separate
+specifications.
+In
+addition
+to
+defining
+the
+abstract
+architecture
+and
+its
+terminology
+and
+conceptual
+framework,
+this
+specification
+also
+serves
+as
+an
+introduction
+to
+the
+WoT
+building
+blocks,
+and
+explains
+their
+interworking:
+</p>
+<ul>
+<li>
+The
+<em>
+Web
+of
+Things
+(WoT)
+Thing
+Description
+</em>
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-wot-thing-description" title= "Web of Things (WoT) Thing Description 1.1">
+WOT-THING-DESCRIPTION
+</a>
+</cite>
+]
+normatively
+provides
+a
+machine-readable
+data
+format
+for
+describing
+the
+metadata
+and
+network-facing
+interfaces
+of
+Things.
+It
+is
+based
+upon
+the
+fundamental
+concepts
+introduced
+in
+this
+document,
+such
+as
+interaction
+affordances.
+</li>
+<li>
+The
+<em>
+Web
+of
+Things
+(WoT)
+Binding
+Templates
+</em>
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-wot-binding-templates" title= "Web of Things (WoT) Binding Templates">
+WOT-BINDING-TEMPLATES
+</a>
+</cite>
+]
+provides
+informational
+guidelines
+on
+how
+to
+define
+network-facing
+interfaces
+in
+Things
+for
+particular
+protocols
+and
+IoT
+ecosystems,
+which
+we
+call
+Protocol
+Bindings.
+The
+document
+also
+provides
+examples
+for
+a
+number
+of
+existing
+IoT
+ecosystems
+and
+standards.
+</li>
+<li>
+The
+<em>
+Web
+of
+Things
+(WoT)
+Discovery
+</em>
+[
+<cite>
+<a class= "bibref" data-link-type="biblio" href="#bib-wot-discovery" title= "Web of Things (WoT) Discovery">
+WOT-DISCOVERY
+</a>
+</cite>
+]
+specification
+defines
+a
+distribution
+mechanism
+for
+WoT
+metadata
+(
+<a href="#dfn-thing-description" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-description-1">
+Thing
+Descriptions
+</a>
+).
+The
+WoT
+Discovery
+process
+uses
+existing
+mechanisms
+for
+first
+contact,
+but
+provides
+for
+access
+control
+before
+serving
+detailed
+metadata.
+It
+includes
+support
+for
+directories
+and
+self-description.
+</li>
+<li>
+The
+<em>
+Web
+of
+Things
+(WoT)
+Scripting
+API
+</em>
+[
+<cite>
+<a class= "bibref" data-link-type="biblio" href="#bib-wot-scripting-api" title= "Web of Things (WoT) Scripting API">
+WOT-SCRIPTING-API
+</a>
+</cite>
+],
+which
+is
+optional,
+enables
+the
+implementation
+of
+the
+application
+logic
+of
+a
+Thing
+using
+a
+common
+JavaScript
+API
+similar
+to
+the
+Web
+browser
+APIs.
+This
+simplifies
+IoT
+application
+development
+and
+enables
+portability
+across
+vendors
+and
+devices.
+</li>
+<li>
+The
+<em>
+Web
+of
+Things
+(WoT)
+Security
+and
+Privacy
+Guidelines
+</em>
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href="#bib-wot-security" title= "Web of Things (WoT) Security and Privacy Guidelines">
+WOT-SECURITY
+</a>
+</cite>
+]
+represent
+a
+cross-cutting
+building
+block.
+This
+informational
+document
+provides
+guidelines
+for
+the
+secure
+implementation
+and
+configuration
+of
+Things,
+and
+discusses
+issues
+which
+should
+be
+considered
+in
+any
+systems
+implementing
+<abbr title= "World Wide Web Consortium">
+W3C
+</abbr>
+WoT.
+However,
+it
+should
+be
+emphasized
+that
+security
+and
+privacy
+can
+only
+be
+fully
+evaluated
+in
+the
+context
+of
+a
+complete
+set
+of
+concrete
+mechanisms
+for
+a
+specific
+implementation,
+which
+goes
+beyond
+the
+scope
+of
+the
+WoT
+abstract
+architecture.
+This
+is
+especially
+true
+when
+the
+WoT
+architecture
+is
+used
+descriptively
+for
+pre-existing
+systems,
+since
+the
+<abbr title= "World Wide Web Consortium">
+W3C
+</abbr>
+WoT
+cannot
+constrain
+the
+behavior
+of
+such
+systems,
+it
+can
+only
+describe
+them.
+In
+this
+document
+we
+also
+discuss
+privacy
+and
+security
+risks
+and
+their
+mitigation
+at
+a
+high
+level
+in
+sections
+<a href= "#sec-security-considerations" class="sec-ref">
+<bdi class= "secno">
+10.
+</bdi>
+Security
+Considerations
+</a>
+and
+<a href= "#sec-privacy-considerations" class="sec-ref">
+<bdi class= "secno">
+11.
+</bdi>
+Privacy
+Considerations
+</a>.
+</li>
+</ul>
+<p>
+This
+specification
+also
+covers
+non-normative
+architectural
+aspects
+and
+conditions
+for
+the
+deployment
+of
+WoT
+systems.
+These
+guidelines
+are
+described
+in
+the
+context
+of
+example
+deployment
+scenarios,
+although
+this
+specification
+does
+not
+require
+specific
+concrete
+implementations.
+</p>
+<p>
+This
+specification
+serves
+as
+an
+umbrella
+for
+<abbr title= "World Wide Web Consortium">
+W3C
+</abbr>
+WoT
+specifications
+and
+defines
+the
+basics
+such
+as
+terminology
+and
+the
+underlying
+abstract
+architecture
+of
+the
+<abbr title= "World Wide Web Consortium">
+W3C
+</abbr>
+Web
+of
+Things.
+In
+summary,
+the
+purpose
+of
+this
+specification
+is
+to
+provide:
+</p>
+<ul>
+<li>
+a
+set
+of
+application
+domains
+in
+<a href= "#sec-application-domains" class="sec-ref">
+<bdi class= "secno">
+4.
+</bdi>
+Application
+Domains
+</a>
+that
+were
+considered
+to
+identify
+use
+cases
+for
+the
+<abbr title= "World Wide Web Consortium">
+W3C
+</abbr>
+WoT
+Architecture,
+</li>
+<li>
+a
+set
+of
+common
+deployment
+patterns
+in
+<a href= "#sec-common-deployment-patterns" class="sec-ref">
+<bdi class= "secno">
+5.
+</bdi>
+Common
+Deployment
+Patterns
+</a>,
+</li>
+<li>
+a
+definition
+of
+the
+abstract
+architecture
+in
+<a href= "#sec-wot-architecture" class="sec-ref">
+<bdi class="secno">
+6.
+</bdi>
+Abstract
+WoT
+System
+Architecture
+</a>,
+</li>
+<li>
+an
+overview
+of
+a
+set
+of
+WoT
+building
+blocks
+and
+their
+interplay
+in
+<a href="#sec-building-blocks" class="sec-ref">
+<bdi class= "secno">
+7.
+</bdi>
+WoT
+Building
+Blocks
+</a>,
+</li>
+<li>
+an
+informative
+guideline
+on
+how
+to
+map
+the
+abstract
+architecture
+to
+concrete
+implementations
+in
+<a href= "#sec-servient-implementation" class="sec-ref">
+<bdi class= "secno">
+8.
+</bdi>
+Abstract
+Servient
+Architecture
+</a>,
+</li>
+<li>
+informative
+examples
+of
+deployment
+scenarios
+in
+<a href= "#sec-deployment-scenario" class="sec-ref">
+<bdi class= "secno">
+9.
+</bdi>
+Example
+WoT
+Deployments
+</a>,
+</li>
+<li>
+and
+a
+set
+of
+high
+level
+security
+and
+privacy
+considerations
+to
+be
+aware
+of
+when
+implementing
+a
+system
+based
+on
+the
+<abbr title= "World Wide Web Consortium">
+W3C
+</abbr>
+WoT
+architecture
+in
+<a href= "#sec-security-considerations" class="sec-ref">
+<bdi class= "secno">
+10.
+</bdi>
+Security
+Considerations
+</a>
+and
+<a href= "#sec-privacy-considerations" class="sec-ref">
+<bdi class= "secno">
+11.
+</bdi>
+Privacy
+Considerations
+</a>,
+respectively.
+</li>
+</ul>
+<p>
+Additional
+requirements,
+use
+cases,
+conceptual
+features
+and
+new
+building
+blocks
+are
+collected
+in
+future
+versions
+of
+the
+<em>
+WoT
+Use
+Cases
+and
+Requirement
+</em>
+<a href= "https://www.w3.org/TR/wot-usecases/">
+https://www.w3.org/TR/wot-usecases/
+</a>
+document.
+</p>
+</section>
+<section id="conformance">
+<div class="header-wrapper">
+<h2 id="x2-conformance">
+<bdi class="secno">
+2.
+</bdi>
+Conformance
+</h2>
+<a class="self-link" href="#conformance" aria-label= "Permalink for Section 2.">
+</a>
+</div>
+<p>
+As
+well
+as
+sections
+marked
+as
+non-normative,
+all
+authoring
+guidelines,
+diagrams,
+examples,
+and
+notes
+in
+this
+specification
+are
+non-normative.
+Everything
+else
+in
+this
+specification
+is
+normative.
+</p>
+<p>
+The
+key
+words
+<em class="rfc2119">
+MAY
+</em>,
+<em class= "rfc2119">
+MUST
+</em>,
+<em class="rfc2119">
+MUST
+NOT
+</em>,
+<em class= "rfc2119">
+SHOULD
+</em>,
+and
+<em class="rfc2119">
+SHOULD
+NOT
+</em>
+in
+this
+document
+are
+to
+be
+interpreted
+as
+described
+in
+<a href= "https://datatracker.ietf.org/doc/html/bcp14">
+BCP
+14
+</a>
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-rfc2119" title= "Key words for use in RFCs to Indicate Requirement Levels">
+RFC2119
+</a>
+</cite>
+]
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-rfc8174" title= "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words">
+RFC8174
+</a>
+</cite>
+]
+when,
+and
+only
+when,
+they
+appear
+in
+all
+capitals,
+as
+shown
+here.
+</p>
+</section>
+<section id="terminology" class="informative">
+<div class="header-wrapper">
+<h2 id="x3-terminology">
+<bdi class="secno">
+3.
+</bdi>
+Terminology
+</h2>
+<a class="self-link" href="#terminology" aria-label= "Permalink for Section 3.">
+</a>
+</div>
+<p>
+<em>
+This
+section
+is
+non-normative.
+</em>
+</p>
+<p>
+This
+specification
+uses
+the
+following
+terms
+as
+defined
+here.
+The
+WoT
+prefix
+is
+used
+to
+avoid
+ambiguity
+for
+terms
+that
+are
+(re)defined
+specifically
+for
+Web
+of
+Things
+concepts.
+</p>
+<p>
+In
+case
+of
+a
+conflict
+of
+a
+definition
+with
+terminology
+used
+in
+another
+WoT
+document,
+the
+definition
+of
+the
+WoT
+Architecture
+takes
+precedence.
+</p>
+<dl>
+<dt>
+<dfn data-plurals="actions" id="dfn-action" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Action
+</dfn>
+</dt>
+<dd>
+An
+Interaction
+Affordance
+that
+allows
+to
+invoke
+a
+function
+of
+the
+Thing,
+which
+manipulates
+state
+(e.g.,
+toggling
+a
+lamp
+on
+or
+off)
+or
+triggers
+a
+process
+on
+the
+Thing
+(e.g.,
+dim
+a
+lamp
+over
+time).
+</dd>
+<dt>
+<dfn data-lt="WoT Anonymous Thing Description|Anonymous TD" class="lint-ignore" id="dfn-wot-anonymous-thing-description" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Anonymous
+TD
+</dfn>
+</dt>
+<dd>
+A
+Thing
+Description
+without
+a
+user-defined
+identifier
+(
+<code>
+id
+</code>
+attribute).
+</dd>
+<dt>
+<dfn id="dfn-connected-device" tabindex="0" aria-haspopup= "dialog" data-dfn-type="dfn">
+Connected
+Device
+</dfn>
+</dt>
+<dd>
+A
+synonym
+for
+<a href="#dfn-device" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-device-1">
+Device
+</a>.
+</dd>
+<dt>
+<dfn data-lt="WoT Binding Templates|Binding Templates" data-plurals="binding template" id="dfn-wot-binding-templates" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Binding
+Templates
+</dfn>
+</dt>
+<dd>
+A
+re-usable
+collection
+of
+blueprints
+that
+enable
+a
+Thing
+Description
+to
+be
+used
+with
+a
+specific
+protocol,
+data
+payload
+format
+or
+an
+IoT
+platform
+that
+combine
+both
+of
+them
+in
+specific
+ways.
+This
+is
+done
+through
+additional
+descriptive
+vocabularies,
+Thing
+Models
+and
+examples
+that
+aim
+to
+guide
+the
+implementers
+of
+Things
+and
+Consumers
+alike.
+</dd>
+<dt>
+<dfn data-plurals="consumed things" id="dfn-consumed-thing" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Consumed
+Thing
+</dfn>
+</dt>
+<dd>
+A
+software
+abstraction
+that
+represents
+a
+remote
+Thing
+used
+by
+the
+local
+application.
+The
+abstraction
+might
+be
+created
+by
+a
+native
+WoT
+Runtime,
+or
+instantiated
+as
+an
+object
+through
+the
+WoT
+Scripting
+API.
+</dd>
+<dt>
+<dfn data-plurals="content types" id="dfn-content-type" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Content
+Type
+</dfn>
+</dt>
+<dd>
+Identifier
+for
+the
+format
+of
+the
+message
+body.
+Also
+known
+as
+media
+type
+and
+MIME
+type
+[
+<cite>
+<a class="bibref" data-link-type= "biblio" href="#bib-rfc2046" title= "Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types">
+RFC2046
+</a>
+</cite>
+].
+</dd>
+<dt>
+<dfn class="lint-ignore" id="dfn-consuming-a-thing" tabindex= "0" aria-haspopup="dialog" data-dfn-type="dfn">
+Consuming
+a
+Thing
+</dfn>
+</dt>
+<dd>
+To
+parse
+and
+process
+a
+TD
+document
+and
+from
+it
+create
+a
+Consumed
+Thing
+software
+abstraction
+as
+interface
+for
+the
+application
+in
+the
+local
+runtime
+environment.
+</dd>
+<dt>
+<dfn data-plurals="consumers" id="dfn-consumer" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Consumer
+</dfn>
+</dt>
+<dd>
+An
+entity
+that
+can
+process
+WoT
+Thing
+Descriptions
+(including
+its
+JSON-based
+representation
+format)
+and
+interact
+with
+Things
+(i.e.,
+consume
+Things).
+</dd>
+<dt>
+<dfn data-plurals="data schemas" id="dfn-data-schema" tabindex= "0" aria-haspopup="dialog" data-dfn-type="dfn">
+Data
+Schema
+</dfn>
+</dt>
+<dd>
+A
+data
+schema
+describes
+the
+information
+model
+and
+the
+related
+payload
+structure
+and
+corresponding
+data
+items
+that
+are
+passed
+between
+<a href="#dfn-thing" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-thing-1">
+Things
+</a>
+and
+<a href= "#dfn-consumer" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-1">
+Consumers
+</a>
+during
+interactions.
+</dd>
+<dt>
+<dfn data-plurals="devices" id="dfn-device" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Device
+</dfn>
+</dt>
+<dd>
+A
+Device
+is
+a
+physical
+entity
+that
+has
+a
+network
+interface.
+Devices
+can
+be
+described
+by
+a
+<a href="#dfn-thing-description" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-description-2">
+Thing
+Description
+</a>
+and
+are
+a
+kind
+of
+<a href="#dfn-thing" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-thing-2">
+Thing
+</a>.
+A
+synonym
+for
+<a href= "#dfn-connected-device" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-connected-device-1">
+Connected
+Device
+</a>.
+Compare
+with
+<a href="#dfn-service" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-service-1">
+Service
+</a>.
+</dd>
+<dt>
+<dfn data-plurals="digital twins" id="dfn-digital-twin" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Digital
+Twin
+</dfn>
+</dt>
+<dd>
+A
+digital
+twin
+is
+type
+of
+<a href="#dfn-virtual-thing" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-virtual-thing-1">
+Virtual
+Thing
+</a>
+that
+resides
+on
+a
+cloud
+or
+edge
+node.
+Digital
+Twins
+may
+be
+used
+to
+represent
+and
+provide
+a
+network
+interface
+for
+real-world
+devices
+which
+may
+not
+be
+continuously
+online
+(see
+also
+<a href="#dfn-shadow" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-shadow-1">
+Shadows
+</a>
+),
+may
+be
+able
+to
+run
+simulations
+of
+new
+applications
+and
+services
+before
+they
+get
+deployed
+to
+the
+real
+devices,
+may
+be
+able
+to
+maintain
+a
+history
+of
+past
+state
+or
+behaviour,
+and
+may
+be
+able
+to
+predict
+future
+state
+or
+behaviour.
+Digital
+Twins
+typically
+have
+more
+functionality
+than
+simple
+<a href="#dfn-shadow" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-shadow-2">
+Shadows
+</a>.
+</dd>
+<dt>
+<dfn class="lint-ignore" id="dfn-directory" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Directory
+</dfn>
+</dt>
+<dd>
+A
+<a href="#dfn-service" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-service-2">
+Service
+</a>
+that
+maintains
+a
+set
+of
+data
+or
+metadata
+describing
+other
+<a href="#dfn-service" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-service-3">
+Services
+</a>
+or
+<a href="#dfn-thing" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-3">
+Things
+</a>.
+An
+example
+would
+be
+a
+<a href= "#dfn-wot-thing-description-directory" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-thing-description-directory-1">
+WoT
+Thing
+Description
+Directory
+</a>.
+</dd>
+<dt>
+<dfn data-lt="WoT Discovery|Discovery" id="dfn-wot-discovery" tabindex="0" aria-haspopup="dialog" data-dfn-type= "dfn">
+Discovery
+</dfn>
+</dt>
+<dd>
+Mechanisms
+defined
+by
+WoT
+for
+distributing
+and
+accessing
+<a href="#dfn-wot-thing-description" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-thing-description-1">
+WoT
+Thing
+Descriptions
+</a>
+on
+the
+network,
+either
+locally
+or
+remotely.
+</dd>
+<dt>
+<dfn data-lt="WoT Discoverer|Discoverer" class="lint-ignore" id="dfn-wot-discoverer" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Discoverer
+</dfn>
+</dt>
+<dd>
+An
+entity
+which
+acts
+as
+a
+client
+of
+a
+WoT
+Discovery
+process
+to
+discover
+and
+fetch
+a
+<a href="#dfn-thing-description" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-description-3">
+Thing
+Description
+</a>,
+e.g.
+by
+being
+introduced
+to
+and
+searching
+a
+<a href= "#dfn-wot-thing-description-directory" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-thing-description-directory-2">
+Thing
+Description
+Directory
+</a>
+exploration
+service
+or
+by
+fetching
+a
+<a href= "#dfn-thing-description" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-description-4">
+Thing
+Description
+</a>
+directly
+from
+the
+well-known
+endpoint
+on
+a
+Thing.
+</dd>
+<dt>
+<dfn data-plurals="domain-specific vocabularies" id= "dfn-domain-specific-vocabulary" tabindex="0" aria-haspopup= "dialog" data-dfn-type="dfn">
+Domain-specific
+Vocabulary
+</dfn>
+</dt>
+<dd>
+Linked
+Data
+vocabulary
+that
+can
+be
+used
+in
+the
+WoT
+Thing
+Description,
+but
+is
+not
+defined
+by
+<abbr title= "World Wide Web Consortium">
+W3C
+</abbr>
+WoT.
+</dd>
+<dt>
+<dfn id="dfn-edge-device" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Edge
+Device
+</dfn>
+</dt>
+<dd>
+A
+device
+that
+provides
+an
+entry
+point
+into
+enterprise
+or
+service
+provider
+core
+networks.
+Examples
+include
+hubs,
+gateways,
+routers,
+switches,
+multiplexers,
+and
+a
+variety
+of
+other
+access
+devices.
+</dd>
+<dt>
+<dfn data-lt="WoT Enriched Thing Description|Enriched TD" class="lint-ignore" id="dfn-wot-enriched-thing-description" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Enriched
+TD
+</dfn>
+</dt>
+<dd>
+A
+Thing
+Description
+embedded
+with
+additional
+attributes
+for
+bookkeeping
+and
+discovery.
+</dd>
+<dt>
+<dfn data-plurals="events" id="dfn-event" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Event
+</dfn>
+</dt>
+<dd>
+An
+Interaction
+Affordance
+that
+describes
+an
+event
+source,
+which
+asynchronously
+pushes
+event
+data
+to
+Consumers
+(e.g.,
+overheating
+alerts).
+</dd>
+<dt>
+<dfn data-lt="WoT Exploration|Exploration" id= "dfn-wot-exploration" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Exploration
+</dfn>
+</dt>
+<dd>
+A
+discovery
+mechanism
+that
+provides
+access
+to
+detailed
+metadata
+in
+the
+form
+of
+one
+or
+more
+Thing
+Descriptions.
+Exploration
+mechanisms
+are
+in
+general
+protected
+by
+security
+mechanism
+and
+are
+accessible
+only
+to
+authorized
+users.
+</dd>
+<dt>
+<dfn data-plurals="exposed things" id="dfn-exposed-thing" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Exposed
+Thing
+</dfn>
+</dt>
+<dd>
+A
+software
+abstraction
+that
+represents
+a
+locally
+hosted
+Thing
+that
+can
+be
+accessed
+over
+the
+network
+by
+remote
+Consumers.
+The
+abstraction
+might
+be
+created
+by
+a
+native
+WoT
+Runtime,
+or
+instantiated
+as
+an
+object
+through
+the
+WoT
+Scripting
+API.
+</dd>
+<dt>
+<dfn class="lint-ignore" id="dfn-exposing-a-thing" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Exposing
+a
+Thing
+</dfn>
+</dt>
+<dd>
+To
+create
+an
+Exposed
+Thing
+software
+abstraction
+in
+the
+local
+runtime
+environment
+to
+manage
+the
+state
+of
+a
+Thing
+and
+interface
+with
+the
+behavior
+implementation.
+</dd>
+<dt>
+<dfn data-plurals="hypermedia controls" id= "dfn-hypermedia-control" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Hypermedia
+Control
+</dfn>
+</dt>
+<dd>
+A
+serialization
+of
+a
+Protocol
+Binding
+in
+hypermedia,
+that
+is,
+either
+a
+Web
+link
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href="#bib-rfc8288" title="Web Linking">
+RFC8288
+</a>
+</cite>
+]
+for
+navigation
+or
+a
+Web
+form
+for
+performing
+other
+operations.
+Forms
+can
+be
+seen
+as
+request
+templates
+provided
+by
+the
+Thing
+to
+be
+completed
+and
+sent
+by
+the
+Consumer.
+</dd>
+<dt>
+<dfn data-plurals="interaction affordances" id= "dfn-interaction-affordance" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Interaction
+Affordance
+</dfn>
+</dt>
+<dd>
+Metadata
+of
+a
+Thing
+that
+shows
+and
+describes
+the
+possible
+choices
+to
+Consumers,
+thereby
+suggesting
+how
+Consumers
+may
+interact
+with
+the
+Thing.
+There
+are
+many
+types
+of
+potential
+affordances,
+but
+<abbr title="World Wide Web Consortium">
+W3C
+</abbr>
+WoT
+defines
+three
+types
+of
+Interaction
+Affordances:
+Properties,
+Actions,
+and
+Events.
+A
+fourth
+Interaction
+Affordance
+is
+navigation,
+which
+is
+already
+available
+on
+the
+Web
+through
+linking.
+</dd>
+<dt>
+<dfn id="dfn-interaction-model" tabindex="0" aria-haspopup= "dialog" data-dfn-type="dfn">
+Interaction
+Model
+</dfn>
+</dt>
+<dd>
+An
+intermediate
+abstraction
+that
+formalizes
+and
+narrows
+the
+mapping
+from
+application
+intent
+to
+concrete
+protocol
+operations.
+In
+<abbr title="World Wide Web Consortium">
+W3C
+</abbr>
+WoT,
+the
+defined
+set
+of
+Interaction
+Affordances
+constitutes
+the
+Interaction
+Model.
+</dd>
+<dt>
+<dfn data-plurals="intermediaries" id="dfn-intermediary" tabindex="0" aria-haspopup="dialog" data-dfn-type= "dfn">
+Intermediary
+</dfn>
+</dt>
+<dd>
+An
+entity
+between
+Consumers
+and
+Things
+that
+can
+proxy,
+augment,
+or
+compose
+Things
+and
+republish
+a
+WoT
+Thing
+Description
+that
+points
+to
+the
+WoT
+Interface
+on
+the
+Intermediary
+instead
+of
+the
+original
+Thing.
+For
+Consumers,
+an
+Intermediary
+may
+be
+indistinguishable
+from
+a
+Thing,
+following
+the
+Layered
+System
+constraint
+of
+REST.
+</dd>
+<dt>
+<dfn data-lt="WoT Introduction|Introduction" id= "dfn-wot-introduction" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Introduction
+</dfn>
+</dt>
+<dd>
+A
+"first
+contact"
+discovery
+mechanism,
+whose
+result
+is
+a
+URL
+that
+references
+an
+exploration
+mechanism.
+Introduction
+mechanisms
+themselves
+should
+not
+directly
+provide
+metadata,
+and
+in
+general
+are
+designed
+to
+be
+open.
+</dd>
+<dt>
+<dfn data-plurals="iot platforms" id="dfn-iot-platform" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+IoT
+Platform
+</dfn>
+</dt>
+<dd>
+A
+specific
+IoT
+ecosystem
+such
+as
+OCF,
+oneM2M,
+or
+Mozilla
+Project
+Things
+with
+its
+own
+specifications
+for
+application-facing
+APIs,
+data
+model,
+and
+protocols
+or
+protocol
+configurations.
+</dd>
+<dt>
+<dfn class="lint-ignore" id="dfn-metadata" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Metadata
+</dfn>
+</dt>
+<dd>
+Data
+that
+provides
+a
+description
+of
+an
+entity's
+abstract
+characteristics.
+For
+example,
+a
+<a href="#dfn-thing-description" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-description-5">
+Thing
+Description
+</a>
+is
+Metadata
+for
+a
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-4">
+Thing
+</a>.
+</dd>
+<dt>
+<dfn data-lt= "Personally Identifiable Information|Personally Identifiable Information (PII)" id="dfn-personally-identifiable-information" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Personally
+Identifiable
+Information
+(PII)
+</dfn>
+</dt>
+<dd>
+Any
+information
+that
+can
+be
+used
+to
+identify
+the
+natural
+person
+to
+whom
+such
+information
+relates,
+or
+is
+or
+might
+be
+directly
+or
+indirectly
+linked
+to
+a
+natural
+person.
+We
+use
+the
+same
+definition
+as
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-iso-iec-29100" title= "Information technology — Security techniques — Privacy framework">
+ISO-IEC-29100
+</a>
+</cite>
+].
+</dd>
+<dt>
+<dfn class="lint-ignore" id="dfn-orchestration" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Orchestration
+</dfn>
+</dt>
+<dd>
+The
+automation
+of
+the
+behavior
+of
+a
+collection
+of
+things.
+Orchestration
+is
+combining
+individual
+things
+with
+rules
+or
+services
+into
+a
+new
+service
+or
+virtual
+<a href="#dfn-thing" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-5">
+Thing
+</a>.
+</dd>
+<dt>
+<dfn id="dfn-partial-td" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Partial
+TD
+</dfn>
+</dt>
+<dd>
+A
+<a href="#dfn-partial-td" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-partial-td-1">
+Partial
+TD
+</a>
+is
+an
+object
+that
+follows
+the
+same
+hierarchical
+structure
+of
+the
+<a href= "#dfn-td" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-td-1">
+TD
+</a>
+information
+model,
+but
+it
+is
+not
+required
+to
+contain
+all
+the
+mandatory
+elements.
+<p>
+Note:
+An
+example
+for
+the
+usage
+of
+a
+<a href="#dfn-partial-td" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-partial-td-2">
+Partial
+TD
+</a>
+is
+in
+<a href= "#dfn-wot-scripting-api" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-scripting-api-1">
+WoT
+Scripting
+API
+</a>,
+where
+it
+is
+used
+as
+input
+for
+the
+creation
+of
+<a href= "#dfn-exposed-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-exposed-thing-1">
+Exposed
+Things
+</a>.
+</p>
+</dd>
+<dt>
+<dfn class="lint-ignore" id="dfn-privacy" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Privacy
+</dfn>
+</dt>
+<dd>
+Freedom
+from
+intrusion
+into
+the
+private
+life
+or
+affairs
+of
+an
+individual
+when
+that
+intrusion
+results
+from
+undue
+or
+illegal
+gathering
+and
+use
+of
+data
+about
+that
+individual.
+We
+use
+the
+same
+definition
+as
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href="#bib-iso-iec-2382" title= "Information technology — Vocabulary">
+ISO-IEC-2382
+</a>
+</cite>
+].
+See
+also
+<a href="#dfn-personally-identifiable-information" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-personally-identifiable-information-1">
+Personally
+Identifiable
+Information
+</a>
+and
+<a href="#dfn-security" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-security-1">
+Security
+</a>,
+as
+well
+as
+other
+related
+definitions
+in
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href="#bib-iso-iec-29100" title= "Information technology — Security techniques — Privacy framework">
+ISO-IEC-29100
+</a>
+</cite>
+].
+</dd>
+<dt>
+<dfn id="dfn-private-security-data" tabindex="0" aria-haspopup= "dialog" data-dfn-type="dfn">
+Private
+Security
+Data
+</dfn>
+</dt>
+<dd>
+Private
+Security
+Data
+is
+that
+component
+of
+a
+Thing's
+<a href= "#dfn-security-configuration" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-security-configuration-1">
+Security
+Configuration
+</a>
+that
+is
+kept
+secret
+and
+is
+not
+shared
+with
+other
+devices
+or
+users.
+An
+example
+would
+be
+private
+keys
+in
+a
+PKI
+system.
+Ideally
+such
+data
+is
+stored
+in
+a
+separate
+memory
+inaccessible
+to
+the
+application
+and
+is
+only
+used
+via
+abstract
+operations,
+such
+as
+signing,
+that
+do
+not
+reveal
+the
+secret
+information
+even
+to
+the
+application
+using
+it.
+</dd>
+<dt>
+<dfn data-plurals="producers" id="dfn-producer" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Producer
+</dfn>
+</dt>
+<dd>
+An
+entity
+that
+can
+create
+WoT
+Thing
+Descriptions
+for
+a
+specific
+Thing.
+</dd>
+<dt>
+<dfn id="dfn-profile" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Profile
+</dfn>
+</dt>
+<dd>
+A
+technical
+specification
+which
+provides
+a
+set
+of
+assertions
+such
+that
+any
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-consumer-2">
+Consumer
+</a>
+which
+conforms
+with
+the
+those
+assertions
+is
+out-of-the-box
+interoperable
+with
+any
+<a href="#dfn-thing" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-thing-6">
+Thing
+</a>
+which
+also
+conforms
+with
+those
+assertions.
+</dd>
+<dt>
+<dfn data-plurals="properties" id="dfn-property" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Property
+</dfn>
+</dt>
+<dd>
+An
+Interaction
+Affordance
+that
+exposes
+state
+of
+the
+Thing.
+This
+state
+can
+then
+be
+retrieved
+(read)
+and
+optionally
+updated
+(write).
+Things
+can
+also
+choose
+to
+make
+Properties
+observable
+by
+notifying
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-consumer-3">
+Consumers
+</a>
+about
+a
+state
+change.
+</dd>
+<dt>
+<dfn data-lt="WoT Protocol Binding|Protocol Binding" data-plurals="protocol bindings" id="dfn-wot-protocol-binding" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Protocol
+Binding
+</dfn>
+</dt>
+<dd>
+The
+mapping
+from
+an
+Interaction
+Affordance
+to
+concrete
+messages
+of
+a
+specific
+protocol,
+thereby
+informing
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-4">
+Consumers
+</a>
+how
+to
+activate
+the
+<a href= "#dfn-interaction-affordance" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-interaction-affordance-1">
+Interaction
+Affordance
+</a>.
+<abbr title="World Wide Web Consortium">
+W3C
+</abbr>
+WoT
+serializes
+Protocol
+Bindings
+as
+<a href= "#dfn-hypermedia-control" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-hypermedia-control-1">
+hypermedia
+controls
+</a>.
+</dd>
+<dt>
+<dfn id="dfn-public-security-metadata" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Public
+Security
+Metadata
+</dfn>
+</dt>
+<dd>
+Public
+Security
+Metadata
+is
+that
+component
+of
+a
+Thing's
+<a href="#dfn-security-configuration" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-security-configuration-2">
+Security
+Configuration
+</a>
+which
+describes
+the
+security
+mechanisms
+and
+access
+rights
+necessary
+to
+access
+a
+Thing.
+It
+does
+not
+include
+any
+secret
+information
+or
+concrete
+data
+(including
+public
+keys),
+and
+does
+not
+by
+itself,
+provide
+access
+to
+the
+Thing.
+Instead,
+it
+describes
+the
+mechanisms
+by
+which
+access
+may
+be
+obtained
+by
+authorized
+users,
+including
+how
+they
+must
+authenticate
+themselves.
+</dd>
+<dt>
+<dfn data-lt="WoT Registrant|Registrant" class="lint-ignore" id="dfn-wot-registrant" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Registrant
+</dfn>
+</dt>
+<dd>
+An
+entity
+which
+registers
+a
+<a href="#dfn-thing-description" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-description-6">
+Thing
+Description
+</a>
+with
+a
+<a href="#dfn-wot-thing-description-directory" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-thing-description-directory-3">
+Thing
+Description
+Directory
+</a>.
+This
+entity
+may
+or
+may
+not
+be
+the
+<a href= "#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-7">
+Thing
+</a>
+that
+the
+registered
+<a href= "#dfn-thing-description" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-description-7">
+Thing
+Description
+</a>
+describes.
+</dd>
+<dt>
+<dfn id="dfn-security" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Security
+</dfn>
+</dt>
+<dd>
+Preservation
+of
+the
+confidentiality,
+integrity
+and
+availability
+of
+information.
+Properties
+such
+as
+authenticity,
+accountability,
+non-repudiation,
+and
+reliability
+may
+also
+be
+involved.
+This
+definition
+is
+adapted
+from
+the
+definition
+of
+<i>
+Information
+Security
+</i>
+in
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href="#bib-iso-iec-27000" title= "Information technology — Security techniques — Information security management systems — Overview and vocabulary">
+ISO-IEC-27000
+</a>
+</cite>
+],
+which
+also
+includes
+additional
+definitions
+of
+each
+of
+the
+more
+specific
+properties
+mentioned.
+Please
+refer
+to
+this
+document
+for
+other
+related
+definitions.
+We
+additionally
+note
+that
+it
+is
+desirable
+that
+these
+properties
+be
+maintained
+both
+in
+normal
+operation
+and
+when
+the
+system
+is
+subject
+to
+attack.
+</dd>
+<dt>
+<dfn id="dfn-security-configuration" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Security
+Configuration
+</dfn>
+</dt>
+<dd>
+The
+combination
+of
+Public
+Security
+Metadata,
+Private
+Security
+Data,
+and
+any
+other
+configuration
+information
+(such
+as
+public
+keys)
+necessary
+to
+operationally
+configure
+the
+security
+mechanisms
+of
+a
+Thing.
+</dd>
+<dt>
+<dfn data-plurals="services" id="dfn-service" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Service
+</dfn>
+</dt>
+<dd>
+A
+Service
+is
+a
+software
+entity
+that
+has
+a
+network
+interface.
+Services
+can
+be
+described
+by
+a
+<a href="#dfn-thing-description" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-description-8">
+Thing
+Description
+</a>
+and
+are
+a
+kind
+of
+<a href="#dfn-thing" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-thing-8">
+Thing
+</a>.
+See
+also
+<a href= "#dfn-virtual-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-virtual-thing-2">
+Virtual
+Thing
+</a>.
+Compare
+with
+<a href="#dfn-device" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-device-2">
+Device
+</a>.
+</dd>
+<dt>
+<dfn data-plurals="servients" id="dfn-servient" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Servient
+</dfn>
+</dt>
+<dd>
+A
+software
+stack
+that
+implements
+the
+WoT
+building
+blocks.
+A
+Servient
+can
+host
+and
+expose
+Things
+and/or
+host
+Consumers
+that
+consume
+Things.
+Servients
+can
+support
+multiple
+Protocol
+Bindings
+to
+enable
+interaction
+with
+different
+IoT
+platforms.
+</dd>
+<dt>
+<dfn data-plurals="shadows" id="dfn-shadow" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Shadow
+</dfn>
+</dt>
+<dd>
+A
+Shadow
+is
+a
+<a href="#dfn-virtual-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-virtual-thing-3">
+Virtual
+Thing
+</a>
+that
+maintains
+a
+copy
+of
+the
+state
+and
+mediates
+interactions
+with
+another
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-9">
+Thing
+</a>.
+A
+Shadow
+aims
+to
+achieve
+eventual
+consistency
+with
+the
+state
+of
+the
+Thing
+it
+represents.
+If
+a
+Shadow
+has
+more
+functionality
+than
+simply
+mirroring
+state
+it
+may
+be
+better
+to
+refer
+to
+it
+as
+a
+<a href= "#dfn-digital-twin" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-digital-twin-1">
+Digital
+Twin
+</a>.
+</dd>
+<dt>
+<dfn data-plurals="subprotocols" id="dfn-subprotocol" tabindex= "0" aria-haspopup="dialog" data-dfn-type= "dfn">
+Subprotocol
+</dfn>
+</dt>
+<dd>
+An
+extension
+mechanism
+to
+a
+transport
+protocol
+that
+must
+be
+known
+to
+interact
+successfully.
+An
+example
+is
+long
+polling
+for
+HTTP.
+</dd>
+<dt>
+<dfn class="lint-ignore" id="dfn-system" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+System
+</dfn>
+</dt>
+<dd>
+An
+entity
+consisting
+of
+multiple
+interacting
+components.
+</dd>
+<dt>
+<dfn data-plurals="tds" id="dfn-td" tabindex="0" aria-haspopup= "dialog" data-dfn-type="dfn">
+TD
+</dfn>
+</dt>
+<dd>
+Short
+for
+<a href="#dfn-wot-thing-description" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-thing-description-2">
+WoT
+Thing
+Description
+</a>.
+</dd>
+<dt>
+<dfn data-plurals="tdds" id="dfn-tdd" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+TDD
+</dfn>
+</dt>
+<dd>
+Short
+for
+<a href="#dfn-wot-thing-description-directory" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-thing-description-directory-4">
+WoT
+Thing
+Description
+Directory
+</a>.
+</dd>
+<dt>
+<dfn class="lint-ignore" id="dfn-td-vocabulary" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+TD
+Vocabulary
+</dfn>
+</dt>
+<dd>
+A
+Linked
+Data
+vocabulary
+controlled
+by
+<abbr title= "World Wide Web Consortium">
+W3C
+</abbr>
+WoT
+to
+tag
+the
+metadata
+of
+Things
+in
+the
+WoT
+Thing
+Description
+including
+communication
+metadata
+of
+WoT
+Binding
+Templates.
+</dd>
+<dt>
+<dfn class="lint-ignore" id="dfn-td-context-extension" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+TD
+Context
+Extension
+</dfn>
+</dt>
+<dd>
+A
+mechanism
+to
+extend
+<a href="#dfn-thing-description" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-description-9">
+Thing
+Descriptions
+</a>
+with
+additional
+<a href="#dfn-vocabulary-term" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-vocabulary-term-1">
+Vocabulary
+Terms
+</a>
+using
+<code>
+@context
+</code>
+as
+specified
+in
+JSON-LD[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-json-ld11" title="JSON-LD 1.1">
+JSON-LD11
+</a>
+</cite>
+].
+It
+is
+the
+basis
+for
+semantic
+annotations
+and
+extensions
+to
+core
+mechanisms
+such
+as
+Protocol
+Bindings,
+Security
+Schemes,
+and
+Data
+Schemas.
+</dd>
+<dt>
+<dfn class="lint-ignore" id="dfn-td-server" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+TD
+Server
+</dfn>
+</dt>
+<dd>
+Short
+for
+<a href="#dfn-wot-thing-description-server" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-thing-description-server-1">
+Thing
+Description
+Server
+</a>.
+</dd>
+<dt>
+<dfn data-plurals="things" id="dfn-thing" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Thing
+</dfn>
+or
+<dfn data-plurals="web things" id="dfn-web-thing" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Web
+Thing
+</dfn>
+</dt>
+<dd>
+An
+abstraction
+of
+a
+physical
+or
+a
+virtual
+entity
+whose
+metadata
+and
+interfaces
+are
+described
+by
+a
+WoT
+Thing
+Description,
+whereas
+a
+virtual
+entity
+is
+the
+composition
+of
+one
+or
+more
+Things.
+</dd>
+<dt>
+<dfn data-lt= "WoT Thing Description Directory|Thing Description Directory" data-plurals="thing description directories" id= "dfn-wot-thing-description-directory" tabindex="0" aria-haspopup= "dialog" data-dfn-type="dfn">
+Thing
+Description
+Directory
+</dfn>
+</dt>
+<dd>
+A
+directory
+service
+for
+TDs
+that
+provides
+a
+Web
+interface
+to
+register
+TDs
+and
+look
+them
+up
+(e.g.,
+using
+JSONPath
+or
+SPARQL
+queries).
+A
+recommended
+API
+and
+feature
+set
+is
+defined
+in
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-wot-discovery" title= "Web of Things (WoT) Discovery">
+WOT-DISCOVERY
+</a>
+</cite>
+],
+and
+is
+used
+as
+an
+optional
+part
+of
+the
+<a href="#dfn-wot-discovery" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-discovery-1">
+WoT
+Discovery
+</a>
+process.
+</dd>
+<dt>
+<dfn id="dfn-td-fragment" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+TD
+Fragment
+</dfn>
+</dt>
+<dd>
+A
+<a href="#dfn-td-fragment" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-td-fragment-1">
+TD
+Fragment
+</a>
+is
+a
+substructure
+of
+the
+data
+model
+of
+a
+TD.
+It
+is
+a
+valid
+object
+structure
+that
+can
+be
+validated
+syntactically
+against
+a
+part
+of
+the
+TD
+information
+model
+defined
+in
+chapter
+5
+of
+the
+<a href= "#dfn-thing-description" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-description-10">
+Thing
+Description
+</a>
+specification,
+however
+the
+fragment
+may
+omit
+some
+context
+that
+allows
+full
+validation.
+</dd>
+<dt>
+<dfn data-lt= "WoT Thing Description Server|Thing Description Server" id= "dfn-wot-thing-description-server" tabindex="0" aria-haspopup= "dialog" data-dfn-type="dfn">
+Thing
+Description
+Server
+</dfn>
+</dt>
+<dd>
+A
+Thing
+Description
+Server
+is
+a
+web
+resource,
+addressed
+by
+a
+URL,
+that
+can
+provide
+a
+Thing
+Description
+when
+accessed.
+Its
+requirements
+are
+defined
+in
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href="#bib-wot-discovery" title= "Web of Things (WoT) Discovery">
+WOT-DISCOVERY
+</a>
+</cite>
+],
+and
+is
+used
+as
+an
+optional
+part
+of
+the
+<a href="#dfn-wot-discovery" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-discovery-2">
+WoT
+Discovery
+</a>
+process.
+</dd>
+<dt>
+<dfn data-lt="WoT Thing Model|Thing Model" data-plurals= "thing models|wot thing models" id="dfn-wot-thing-model" tabindex= "0" aria-haspopup="dialog" data-dfn-type="dfn">
+Thing
+Model
+</dfn>
+</dt>
+<dd>
+A
+<a href="#dfn-wot-thing-model" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-thing-model-1">
+Thing
+Model
+</a>
+is
+a
+description
+for
+a
+class
+of
+Things
+that
+have
+the
+same
+capabilities.
+It
+describes
+the
+<a href="#dfn-property" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-property-1">
+Properties
+</a>,
+<a href="#dfn-action" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-action-1">
+Actions
+</a>,
+and
+<a href="#dfn-event" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-event-1">
+Events
+</a>
+and
+common
+metadata
+that
+are
+shared
+for
+an
+entire
+group
+of
+<a href="#dfn-thing" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-10">
+Things
+</a>.
+Compared
+to
+a
+Thing
+Description,
+a
+Thing
+Model
+does
+not
+contain
+enough
+information
+to
+identify
+or
+interact
+with
+a
+Thing
+instance.
+</dd>
+<dt>
+<dfn data-plurals="transport protocols" id= "dfn-transport-protocol" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Transport
+Protocol
+</dfn>
+</dt>
+<dd>
+The
+underlying,
+standardized
+application
+layer
+protocol
+without
+application-specific
+requirements
+or
+constraints
+on
+options
+or
+subprotocol
+mechanisms.
+Examples
+are
+HTTP,
+CoAP,
+or
+MQTT.
+</dd>
+<dt>
+<dfn id="dfn-trusted-environment" tabindex="0" aria-haspopup= "dialog" data-dfn-type="dfn">
+Trusted
+Environment
+</dfn>
+</dt>
+<dd>
+Set
+of
+devices
+that
+assume
+each
+other's
+claims
+of
+identity
+are
+authentic
+without
+proof
+and
+allow
+relatively
+unrestricted
+access
+to
+one
+another
+over
+a
+common
+protected
+network.
+</dd>
+<dt>
+<dfn id="dfn-virtual-thing" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Virtual
+Thing
+</dfn>
+</dt>
+<dd>
+A
+<a href="#dfn-service" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-service-4">
+Service
+</a>
+that
+represents,
+augments
+the
+functionality
+of,
+provides
+an
+improved
+interface
+to,
+or
+stands
+in
+place
+of
+one
+or
+more
+other
+<a href="#dfn-thing" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-11">
+Things
+</a>.
+A
+Virtual
+Thing
+will
+often
+act
+as
+an
+<a href="#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-1">
+Intermediary
+</a>.
+Examples
+include
+<a href="#dfn-shadow" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-shadow-3">
+Shadows
+</a>
+and
+<a href="#dfn-digital-twin" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-digital-twin-2">
+Digital
+Twins
+</a>.
+</dd>
+<dt>
+<dfn id="dfn-vocabulary" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Vocabulary
+</dfn>
+</dt>
+<dd>
+A
+collection
+of
+<a href="#dfn-vocabulary-term" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-vocabulary-term-2">
+Vocabulary
+Terms
+</a>,
+identified
+by
+a
+namespace
+IRI.
+</dd>
+<dt>
+<dfn id="dfn-term" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Term
+</dfn>
+and
+<dfn data-plurals= "vocabulary terms" id="dfn-vocabulary-term" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Vocabulary
+Term
+</dfn>
+</dt>
+<dd>
+A
+character
+string.
+When
+a
+<a href="#dfn-term" class= "internalDFN" data-link-type="dfn" id="ref-for-dfn-term-1">
+Term
+</a>
+is
+part
+of
+a
+<a href="#dfn-vocabulary" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-vocabulary-1">
+Vocabulary
+</a>,
+i.e.,
+prefixed
+by
+a
+namespace
+IRI[
+<cite>
+<a class="bibref" data-link-type="biblio" href="#bib-rfc3987" title= "Internationalized Resource Identifiers (IRIs)">
+RFC3987
+</a>
+</cite>
+],
+it
+is
+called
+a
+<a href="#dfn-vocabulary-term" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-vocabulary-term-3">
+Vocabulary
+Term
+</a>.
+For
+the
+sake
+of
+readability,
+<a href= "#dfn-vocabulary-term" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-vocabulary-term-4">
+Vocabulary
+Terms
+</a>
+present
+in
+this
+document
+are
+always
+written
+in
+a
+compact
+form
+and
+not
+as
+full
+IRIs.
+</dd>
+<dt>
+<dfn id="dfn-wot-interface" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+WoT
+Interface
+</dfn>
+</dt>
+<dd>
+The
+network-facing
+interface
+of
+a
+Thing
+that
+is
+described
+by
+a
+WoT
+Thing
+Description.
+</dd>
+<dt>
+<dfn id="dfn-wot-profile" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+WoT
+Profile
+</dfn>
+</dt>
+<dd>
+Synonym
+for
+<a href="#dfn-profile" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-profile-1">
+Profile
+</a>
+</dd>
+<dt>
+<dfn id="dfn-wot-runtime" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+WoT
+Runtime
+</dfn>
+</dt>
+<dd>
+A
+runtime
+system
+that
+maintains
+an
+execution
+environment
+for
+applications,
+and
+is
+able
+to
+expose
+and/or
+consume
+Things,
+to
+process
+WoT
+Thing
+Descriptions,
+to
+maintain
+Security
+Configurations,
+and
+to
+interface
+with
+Protocol
+Binding
+implementations.
+A
+WoT
+Runtime
+may
+have
+a
+custom
+API
+or
+use
+the
+optional
+WoT
+Scripting
+API.
+</dd>
+<dt>
+<dfn id="dfn-wot-scripting-api" tabindex="0" aria-haspopup= "dialog" data-dfn-type="dfn">
+WoT
+Scripting
+API
+</dfn>
+</dt>
+<dd>
+The
+application-facing
+programming
+interface
+provided
+by
+a
+Servient
+in
+order
+to
+ease
+the
+implementation
+of
+behavior
+or
+applications
+running
+in
+a
+WoT
+Runtime.
+It
+is
+comparable
+to
+the
+Web
+browser
+APIs.
+The
+WoT
+Scripting
+API
+is
+an
+optional
+building
+block
+for
+<abbr title="World Wide Web Consortium">
+W3C
+</abbr>
+WoT.
+</dd>
+<dt>
+<dfn class="lint-ignore" id="dfn-wot-servient" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+WoT
+Servient
+</dfn>
+</dt>
+<dd>
+Synonym
+for
+Servient.
+</dd>
+<dt>
+<dfn data-plurals="wot thing descriptions" id= "dfn-wot-thing-description" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+WoT
+Thing
+Description
+</dfn>
+or
+<dfn data-plurals="thing descriptions" id="dfn-thing-description" tabindex="0" aria-haspopup="dialog" data-dfn-type="dfn">
+Thing
+Description
+</dfn>
+</dt>
+<dd>
+Structured
+data
+describing
+a
+Thing.
+A
+WoT
+Thing
+Description
+comprises
+general
+metadata,
+domain-specific
+metadata,
+Interaction
+Affordances
+(which
+include
+the
+supported
+Protocol
+Bindings),
+and
+links
+to
+related
+Things.
+The
+WoT
+Thing
+Description
+format
+is
+the
+central
+building
+block
+of
+<abbr title= "World Wide Web Consortium">
+W3C
+</abbr>
+WoT.
+</dd>
+</dl>
+<section id="device-categories">
+<div class="header-wrapper">
+<h3 id="x3-1-device-categories">
+<bdi class="secno">
+3.1
+</bdi>
+Device
+Categories
+</h3>
+<a class="self-link" href="#device-categories" aria-label= "Permalink for Section 3.1">
+</a>
+</div>
+<p>
+In
+a
+deployment
+of
+WoT
+conforming
+to
+the
+<a href= "https://www.w3.org/TR/wot-architecture/#architecture-abstract">
+WoT
+Abstract
+Architecture
+</a>
+we
+see
+a
+variety
+of
+different
+device
+types.
+They
+range
+(sorted
+in
+the
+order
+of
+footprint
+and
+capabilities)
+from
+small
+embedded
+<em>
+node
+</em>
+devices
+to
+<em>
+gateways
+</em>
+or
+<em>
+hubs
+</em>
+to
+powerful
+<em>
+edge
+</em>
+devices
+and
+<em>
+cloud
+</em>
+servers.
+Interoperability
+between
+these
+devices
+implies
+that
+a
+core
+set
+of
+features
+and
+functionalities
+is
+available
+on
+<em>
+all
+</em>
+of
+them.
+</p>
+<p>
+The
+following
+device
+categories
+describe
+the
+footprint
+and
+characteristics
+of
+typical
+representatives
+of
+these
+classes.
+This
+is
+used
+to
+identify
+the
+possible
+features
+and
+use
+cases
+for
+these
+device
+classes.
+</p>
+<p>
+These
+categories
+are
+aligned
+with
+the
+classes
+defined
+by
+the
+IETF
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-rfc7228" title= "Terminology for Constrained-Node Networks">
+RFC7228
+</a>
+</cite>
+]
+for
+constrained
+devices,
+however
+the
+classes
+have
+been
+extended
+to
+larger
+devices
+and
+bounds
+on
+typical
+sizes
+of
+RAM
+and
+Flash/ROM
+are
+provided.
+Memory
+and
+storage
+size
+are
+both
+easier
+to
+quantify
+and
+more
+limiting
+than
+performance,
+so
+that
+is
+the
+basis
+of
+this
+categorization.
+This
+is
+not
+a
+strict
+categorization.
+Categories
+may
+overlap
+and
+not
+all
+memory
+may
+be
+available
+for
+user
+applications.
+</p>
+<table class="def">
+<tbody>
+<tr>
+<th>
+Category
+</th>
+<th>
+data
+size
+(RAM)
+</th>
+<th>
+code
+size
+(Flash,
+ROM,
+...)
+</th>
+<th>
+Typical
+Representative
+</th>
+<th>
+Remarks,
+typical
+application
+scenarios
+</th>
+</tr>
+<tr>
+<td>
+Class-0,
+C0
+</td>
+<td>
+&lt;&lt;
+10
+KiB
+</td>
+<td>
+&lt;&lt;
+100
+KiB
+</td>
+<td>
+small
+footprint
+microcontrollers
+</td>
+<td>
+Sensor
+nodes
+without
+secure
+communication
+</td>
+</tr>
+<tr>
+<td>
+Class-1,
+C1
+</td>
+<td>
+~
+10
+KiB
+</td>
+<td>
+~
+100
+KiB
+</td>
+<td>
+microcontrollers
+</td>
+<td>
+Sensors
+that
+typically
+supports
+secure
+communication
+protocols
+such
+as
+TLS,
+DTLS
+</td>
+</tr>
+<tr>
+<td>
+Class-2,
+C2
+</td>
+<td>
+~
+64
+KiB
+</td>
+<td>
+~
+256
+KiB
+</td>
+<td>
+connected
+limited
+device
+</td>
+<td>
+Small
+embedded
+devices
+such
+as
+M2M
+communication
+nodes,
+smart
+meters,
+sensor
+nodes
+and
+other
+embedded
+appliances,
+home
+appliances,
+low-end
+TV
+set-top
+boxes,
+and
+point
+of
+sale
+terminals
+are
+some
+examples.
+</td>
+</tr>
+<tr>
+<td>
+Class-3,
+C3
+</td>
+<td>
+~
+64-256
+KiB
+</td>
+<td>
+~
+256
+KiB
+-
+several
+MBs
+</td>
+<td>
+ISP
+gateway
+</td>
+<td>
+Small
+home
+and
+industrial
+gateways
+</td>
+</tr>
+<tr>
+<td>
+Class-4,
+C4
+</td>
+<td>
+~
+256
+KiB
+-
+several
+MB
+</td>
+<td>
+~
+1
+MB
+-
+several
+MB
+</td>
+<td>
+gateway/hub
+</td>
+<td>
+Large
+home
+and
+industrial
+gateways
+</td>
+</tr>
+<tr>
+<td>
+Class-5,
+C5
+</td>
+<td>
+~
+1
+-
+8
+GB
+</td>
+<td>
+~
+1
+-
+16
+GB
+</td>
+<td>
+edge
+</td>
+<td>
+Small
+edge
+servers
+</td>
+</tr>
+<tr>
+<td>
+Class-6,
+C6
+</td>
+<td>
+~
+several
+GB
+</td>
+<td>
+~
+several
+GB
+</td>
+<td>
+edge
+</td>
+<td>
+Large
+edge
+servers
+</td>
+</tr>
+<tr>
+<td>
+Class-7,
+C7
+</td>
+<td>
+~
+several
+GB
+</td>
+<td>
+~
+several
+GB
+</td>
+<td>
+cloud
+</td>
+<td>
+Cloud
+systems
+with
+multiple
+compute
+nodes
+</td>
+</tr>
+</tbody>
+</table>
+<div class="note" role="note" id="issue-container-generatedID">
+<div role="heading" class="note-title marker" id="h-note" aria-level="4">
+<span>
+Note
+</span>
+<span class="issue-label">:
+Category
+Borders
+</span>
+</div>
+<p class="">
+Category
+borders
+are
+soft
+borders
+and
+categories
+are
+not
+exclusive,
+i.e.
+there
+are
+application
+scenarios
+that
+can
+be
+implemented
+by
+devices
+from
+several
+categories.
+For
+secure
+communications
+we
+consider
+devices
+that
+support
+TLS/HTTP,
+DTLS/CoAP,
+and
+similar
+secure
+protocols.
+</p>
+</div>
+</section>
+</section>
+<section id="sec-application-domains" class="informative">
+<div class="header-wrapper">
+<h2 id="x4-application-domains">
+<bdi class="secno">
+4.
+</bdi>
+Application
+Domains
+</h2>
+<a class="self-link" href="#sec-application-domains" aria-label= "Permalink for Section 4.">
+</a>
+</div>
+<p>
+<em>
+This
+section
+is
+non-normative.
+</em>
+</p>
+<p>
+This
+section
+presents
+the
+application
+domains
+targeted
+by
+the
+<abbr title="World Wide Web Consortium">
+W3C
+</abbr>
+WoT
+and
+which
+are
+used
+to
+derive
+the
+abstract
+architecture
+discussed
+in
+<a href= "#sec-building-blocks" class="sec-ref">
+<bdi class="secno">
+7.
+</bdi>
+WoT
+Building
+Blocks
+</a>.
+</p>
+<p>
+These
+application
+domains
+are
+motivated
+by
+the
+use
+cases
+that
+are
+described
+in
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href="#bib-wot-use-cases-requirements" title= "Web of Things (WoT) Use Cases and Requirements">
+WOT-USE-CASES-REQUIREMENTS
+</a>
+</cite>
+].
+</p>
+<p>
+The
+Web
+of
+Things
+architecture
+does
+not
+put
+any
+limitations
+on
+use
+cases
+and
+application
+domains.
+Various
+application
+domains
+have
+been
+considered
+to
+collect
+common
+patterns
+that
+have
+to
+be
+satisfied
+by
+the
+abstract
+architecture.
+</p>
+<p>
+The
+following
+sections
+are
+not
+exhaustive.
+Rather
+they
+serve
+as
+illustrations,
+where
+connected
+things
+can
+provide
+additional
+benefit
+or
+enable
+new
+scenarios.
+</p>
+<section id="consumer-use-cases">
+<div class="header-wrapper">
+<h3 id="x4-1-consumer">
+<bdi class="secno">
+4.1
+</bdi>
+Consumer
+</h3>
+<a class="self-link" href="#consumer-use-cases" aria-label= "Permalink for Section 4.1">
+</a>
+</div>
+<p>
+In
+the
+consumer
+space
+there
+are
+multiple
+assets
+that
+benefit
+from
+being
+connected.
+Lights
+and
+air
+conditioners
+can
+be
+turned
+off
+based
+on
+room
+occupancy.
+Window
+blinds
+can
+be
+closed
+automatically
+based
+on
+weather
+conditions
+and
+presence.
+Energy
+and
+other
+resource
+consumption
+can
+be
+optimized
+based
+on
+usage
+patterns
+and
+predictions.
+</p>
+<p>
+The
+consumer
+scenario
+in
+this
+section
+describes
+the
+Smart
+Home
+use
+case.
+</p>
+<p>
+<a href="#smart-home" class="fig-ref" title="Smart Home">
+Figure
+<bdi class="">
+1
+</bdi>
+</a>
+shows
+an
+example
+of
+a
+Smart
+Home.
+In
+this
+case,
+gateways
+are
+connected
+to
+edge
+devices
+such
+as
+sensors,
+cameras
+and
+home
+appliances
+through
+corresponding
+local
+communication
+protocols
+such
+as
+KNX,
+ECHONET,
+ZigBee,
+DECT
+ULE
+and
+Wi-SUN.
+Multiple
+gateways
+can
+exist
+in
+one
+home,
+while
+each
+gateway
+can
+support
+multiple
+local
+protocols.
+</p>
+<p>
+Gateways
+can
+be
+connected
+to
+the
+cloud
+through
+the
+internet,
+while
+some
+appliances
+can
+be
+connected
+to
+the
+cloud
+directly.
+Services
+running
+in
+the
+cloud
+collect
+data
+from
+edge
+devices
+and
+analyze
+the
+data,
+then
+provide
+value
+to
+users
+through
+the
+edge
+devices
+and
+other
+UX
+devices.
+</p>
+<figure id="smart-home">
+<img src= "images/wot-use-cases/smart-home.png" srcset= "images/wot-use-cases/smart-home.svg" class="wot-arch-diagram" alt= "smart home use case" />
+<figcaption>
+<a class="self-link" href="#smart-home">
+Figure
+<bdi class="figno">
+1
+</bdi>
+</a>
+<span class="fig-title">
+Smart
+Home
+</span>
+</figcaption>
+</figure>
+<p>
+Smart
+home
+provides
+consumer
+benefits
+such
+as
+remote
+access
+and
+control,
+voice
+control
+and
+home
+automation.
+Smart
+home
+also
+enables
+device
+manufacturers
+to
+monitor
+and
+maintain
+devices
+remotely.
+Smart
+home
+can
+realize
+value
+added
+services
+such
+as
+energy
+management
+and
+security
+surveillance.
+</p>
+</section>
+<section id="industrial-iot-usecases">
+<div class="header-wrapper">
+<h3 id="x4-2-industrial">
+<bdi class="secno">
+4.2
+</bdi>
+Industrial
+</h3>
+<a class="self-link" href="#industrial-iot-usecases" aria-label= "Permalink for Section 4.2">
+</a>
+</div>
+<p>
+The
+industrial
+use
+cases
+in
+this
+section
+are
+applicable
+to
+different
+industry
+verticals.
+<br />
+Due
+to
+the
+nature
+of
+overlaps
+in
+the
+application
+scenarios,
+different
+verticals
+have
+similar
+use
+cases.
+</p>
+<section id="example-smart-factory">
+<div class="header-wrapper">
+<h4 id="x4-2-1-example-smart-factory">
+<bdi class= "secno">
+4.2.1
+</bdi>
+Example:
+Smart
+Factory
+</h4>
+<a class="self-link" href="#example-smart-factory" aria-label= "Permalink for Section 4.2.1">
+</a>
+</div>
+<p>
+<a href="#smart-factory" class="fig-ref" title= "Smart Factory">
+Figure
+<bdi class="">
+2
+</bdi>
+</a>
+shows
+an
+example
+of
+a
+Smart
+Factory.
+In
+this
+case,
+field-level,
+cell
+and
+line
+controllers
+automate
+different
+factory
+equipment
+based
+on
+industrial
+communication
+protocols
+such
+as
+PROFINET,
+Modbus,
+OPC
+UA
+TSN,
+EtherCAT,
+or
+CAN.
+An
+industrial
+edge
+device
+collects
+selected
+data
+from
+various
+controllers
+and
+makes
+it
+available
+to
+a
+cloud
+backend
+service,
+e.g.,
+for
+remote
+monitoring
+via
+a
+dashboard
+or
+analyzes
+it
+for
+preventive
+maintenance.
+</p>
+<figure id="smart-factory">
+<img src= "images/wot-use-cases/smart_factory_new.png" srcset= "images/wot-use-cases/smart_factory_new.svg" class= "wot-arch-diagram" alt="smart factory use case" />
+<figcaption>
+<a class="self-link" href="#smart-factory">
+Figure
+<bdi class="figno">
+2
+</bdi>
+</a>
+<span class="fig-title">
+Smart
+Factory
+</span>
+</figcaption>
+</figure>
+</section>
+<p>
+Smart
+factories
+require
+advanced
+monitoring
+of
+the
+connected
+manufacturing
+equipment
+as
+well
+of
+the
+manufactured
+products.
+They
+benefit
+from
+predictions
+of
+machine
+failures
+and
+early
+discovery
+of
+anomalies
+to
+prevent
+costly
+downtime
+and
+maintenance
+efforts.
+</p>
+<p>
+Additionally,
+monitoring
+of
+connected
+manufacturing
+equipment
+and
+the
+environment
+at
+the
+production
+facility
+for
+the
+presence
+of
+poisonous
+gases,
+excessive
+noise
+or
+heat
+increases
+the
+safety
+of
+the
+workers
+and
+reduces
+the
+risks
+of
+incidents
+or
+accidents.
+</p>
+<p>
+Real-time
+monitoring
+and
+KPI
+calculations
+of
+production
+equipment
+helps
+to
+detect
+productivity
+problems
+and
+optimize
+the
+supply
+chain.
+</p>
+</section>
+<section id="sec-transportationlogistics">
+<div class="header-wrapper">
+<h3 id="transportationlogistics">
+<bdi class="secno">
+4.3
+</bdi>
+Transportation
+&amp;
+Logistics
+</h3>
+<a class="self-link" href="#transportationlogistics" aria-label= "Permalink for Section 4.3">
+</a>
+</div>
+<p>
+Monitoring
+of
+vehicles,
+fuel
+costs,
+maintenance
+needs
+and
+assignments
+helps
+to
+optimize
+the
+full
+utilization
+of
+the
+vehicle
+fleet.
+</p>
+<p>
+Shipments
+can
+be
+tracked
+to
+be
+en-route
+to
+ensure
+consistent
+quality
+and
+condition
+of
+the
+transported
+goods.
+This
+is
+especially
+useful
+to
+assert
+the
+integrity
+of
+the
+cold-chain
+from
+warehouses
+to
+refrigerated
+trucks
+to
+delivery.
+</p>
+<p>
+Centralized
+monitoring
+and
+management
+of
+stock
+in
+warehouses
+and
+yards
+can
+prevent
+out
+of
+stock
+and
+excessive
+stock
+situations.
+</p>
+</section>
+<section id="sec-utilities">
+<div class="header-wrapper">
+<h3 id="utilities">
+<bdi class="secno">
+4.4
+</bdi>
+Utilities
+</h3>
+<a class="self-link" href="#utilities" aria-label= "Permalink for Section 4.4">
+</a>
+</div>
+<p>
+Automated
+reading
+of
+residential
+and
+C&amp;I
+(Commercial
+and
+Industrial)
+meters,
+and
+billing
+offers
+continuous
+insights
+into
+resource
+consumption
+and
+potential
+bottlenecks.
+</p>
+<p>
+Monitoring
+the
+condition
+and
+output
+of
+distributed
+renewable
+energy
+generation
+equipment
+enables
+optimization
+of
+distributed
+energy
+resources.
+</p>
+<p>
+Monitoring
+and
+remote-controlling
+of
+distribution
+equipment
+helps
+to
+automate
+the
+distribution
+process.
+</p>
+<p>
+Continuous
+monitoring
+of
+generation
+and
+distribution
+infrastructure
+is
+improving
+safety
+of
+utilities
+crew
+in
+the
+field.
+</p>
+</section>
+<section id="sec-oilandgas">
+<div class="header-wrapper">
+<h3 id="oilandgas">
+<bdi class="secno">
+4.5
+</bdi>
+Oil
+and
+Gas
+</h3>
+<a class="self-link" href="#oilandgas" aria-label= "Permalink for Section 4.5">
+</a>
+</div>
+<p>
+Offshore
+platform
+monitoring,
+leakage
+detection
+and
+prediction
+of
+pipelines
+as
+well
+as
+monitoring
+and
+controlling
+the
+levels
+in
+tanks
+and
+reservoirs
+helps
+to
+improve
+the
+industrial
+safety
+for
+the
+workforce
+as
+well
+as
+for
+the
+environment.
+</p>
+<p>
+Automated
+calculation
+of
+a
+distributed
+stock
+through
+various
+storage
+tanks
+and
+delivery
+pipes/trucks
+allows
+for
+improved
+planning
+and
+resource
+optimization.
+</p>
+</section>
+<section id="sec-insurance">
+<div class="header-wrapper">
+<h3 id="insurance">
+<bdi class="secno">
+4.6
+</bdi>
+Insurance
+</h3>
+<a class="self-link" href="#insurance" aria-label= "Permalink for Section 4.6">
+</a>
+</div>
+<p>
+Proactive
+Asset
+Monitoring
+of
+high
+value
+assets
+such
+as
+connected
+structures,
+fleet
+vehicles,
+etc.
+mitigates
+the
+risk
+of
+severe
+damage
+and
+high
+costs
+due
+to
+predictions
+and
+early
+detection
+of
+incidents.
+</p>
+<p>
+Usage
+based
+insurance
+can
+be
+offered
+with
+usage
+tracking
+and
+customized
+insurance
+policies.
+</p>
+<p>
+Predictive
+weather
+monitoring
+and
+re-routing
+fleet
+vehicles
+to
+covered
+garages
+can
+limit
+loss
+due
+to
+hail
+damage,
+tree
+damage.
+</p>
+</section>
+<section id="sec-engineering-and-construction">
+<div class="header-wrapper">
+<h3 id="engineering-and-construction">
+<bdi class="secno">
+4.7
+</bdi>
+Engineering
+and
+Construction
+</h3>
+<a class="self-link" href="#engineering-and-construction" aria-label="Permalink for Section 4.7">
+</a>
+</div>
+<p>
+Monitoring
+for
+industrial
+safety
+reduces
+the
+risks
+of
+security
+hazards.
+Monitoring
+of
+assets
+at
+construction
+site
+can
+prevent
+damage
+and
+loss.
+</p>
+</section>
+<section id="sec-agriculture">
+<div class="header-wrapper">
+<h3 id="agriculture">
+<bdi class="secno">
+4.8
+</bdi>
+Agriculture
+</h3>
+<a class="self-link" href="#agriculture" aria-label= "Permalink for Section 4.8">
+</a>
+</div>
+<p>
+Soil
+condition
+monitoring
+and
+creating
+optimal
+plans
+for
+watering,
+fertilizing
+as
+well
+as
+monitoring
+the
+produce
+conditions
+optimize
+the
+quality
+and
+output
+of
+agricultural
+produce.
+</p>
+</section>
+<section id="sec-healthcare">
+<div class="header-wrapper">
+<h3 id="healthcare">
+<bdi class="secno">
+4.9
+</bdi>
+Healthcare
+</h3>
+<a class="self-link" href="#healthcare" aria-label= "Permalink for Section 4.9">
+</a>
+</div>
+<p>
+Data
+collection
+and
+analytics
+of
+clinical
+trial
+data
+helps
+to
+gain
+insights
+into
+new
+areas.
+</p>
+<p>
+Remote
+patient
+monitoring
+mitigates
+the
+risk
+of
+undetected
+critical
+situations
+for
+elderly
+people
+and
+patients
+after
+hospitalization.
+</p>
+</section>
+<section id="sec-environmentmonitoring">
+<div class="header-wrapper">
+<h3 id="environmentmonitoring">
+<bdi class="secno">
+4.10
+</bdi>
+Environment
+Monitoring
+</h3>
+<a class="self-link" href="#environmentmonitoring" aria-label= "Permalink for Section 4.10">
+</a>
+</div>
+<p>
+Environment
+monitoring
+typically
+relies
+on
+a
+lot
+of
+distributed
+sensors
+that
+send
+their
+measurement
+data
+to
+common
+gateways,
+edge
+devices
+and
+cloud
+services.
+</p>
+<p>
+Monitoring
+of
+air
+pollution,
+water
+pollution
+and
+other
+environmental
+risk
+factors
+such
+as
+fine
+dust,
+ozone,
+volatile
+organic
+compound,
+radioactivity,
+temperature,
+humidity
+to
+detect
+critical
+environment
+conditions
+can
+prevent
+unrecoverable
+health
+or
+environment
+damages.
+</p>
+</section>
+<section id="sec-smart-cities">
+<div class="header-wrapper">
+<h3 id="smartcities">
+<bdi class="secno">
+4.11
+</bdi>
+Smart
+Cities
+</h3>
+<a class="self-link" href="#smartcities" aria-label= "Permalink for Section 4.11">
+</a>
+</div>
+<p>
+Monitoring
+of
+Bridges,
+Dams,
+Levees,
+Canals
+for
+material
+condition,
+deterioration,
+vibrations
+discovers
+maintenance
+repair
+work
+and
+prevents
+significant
+damage.
+Monitoring
+of
+highways
+and
+providing
+appropriate
+signage
+ensures
+optimized
+traffic
+flow.
+</p>
+<p>
+Smart
+Parking
+is
+optimizing
+and
+tracking
+the
+usage
+and
+availability
+of
+parking
+spaces
+and
+automates
+billing/reservations.
+</p>
+<p>
+Smart
+control
+of
+street
+lights
+based
+on
+presence
+detection,
+weather
+predictions,
+etc.
+reduces
+cost.
+</p>
+<p>
+Garbage
+containers
+can
+be
+monitored
+to
+optimize
+the
+waste
+management
+and
+the
+trash
+collection
+route.
+</p>
+</section>
+<section id="sec-smart-buildings">
+<div class="header-wrapper">
+<h3 id="smartbuildings">
+<bdi class="secno">
+4.12
+</bdi>
+Smart
+Buildings
+</h3>
+<a class="self-link" href="#smartbuildings" aria-label= "Permalink for Section 4.12">
+</a>
+</div>
+<p>
+Monitoring
+the
+energy
+usage
+throughout
+the
+building
+helps
+to
+optimize
+resource
+consumption
+and
+reduce
+waste.
+</p>
+<p>
+Monitoring
+the
+equipment
+in
+the
+buildings
+such
+as
+HVAC,
+Elevators,
+etc.
+and
+fixing
+problems
+early
+improves
+the
+satisfaction
+of
+occupants.
+</p>
+</section>
+<section id="sec-connected-car">
+<div class="header-wrapper">
+<h3 id="connectedcar">
+<bdi class="secno">
+4.13
+</bdi>
+Connected
+Car
+</h3>
+<a class="self-link" href="#connectedcar" aria-label= "Permalink for Section 4.13">
+</a>
+</div>
+<p>
+Monitoring
+of
+operation
+status,
+prediction
+of
+service
+needs
+optimizes
+maintenance
+needs
+and
+costs.
+Driver
+safety
+is
+enhanced
+with
+notifications
+of
+an
+early
+warning
+system
+for
+critical
+road
+and
+traffic
+conditions.
+</p>
+<section id="connected-car-example">
+<div class="header-wrapper">
+<h4 id="connectedcar-example">
+<bdi class="secno">
+4.13.1
+</bdi>
+Connected
+Car
+Example
+</h4>
+<a class="self-link" href="#connectedcar-example" aria-label= "Permalink for Section 4.13.1">
+</a>
+</div>
+<p>
+<a href="#connected-car" class="fig-ref" title= "Connected Car">
+Figure
+<bdi class="">
+3
+</bdi>
+</a>
+shows
+an
+example
+of
+a
+Connected
+Car.
+In
+this
+case,
+a
+gateway
+connects
+to
+car
+components
+through
+CAN
+and
+to
+the
+car
+navigation
+system
+through
+a
+proprietary
+interface.
+Services
+running
+in
+the
+cloud
+collect
+data
+pushed
+from
+car
+components
+and
+analyze
+the
+data
+from
+multiple
+cars
+to
+determine
+traffic
+patterns.
+The
+gateway
+can
+also
+consume
+cloud
+services,
+in
+this
+case,
+to
+get
+traffic
+data
+and
+show
+it
+to
+the
+driver
+through
+the
+car
+navigation
+system.
+</p>
+<figure id="connected-car">
+<img src= "images/wot-use-cases/connected-car.png" srcset= "images/wot-use-cases/connected-car.svg" class="wot-arch-diagram" alt="connected car use case" />
+<figcaption>
+<a class="self-link" href="#connected-car">
+Figure
+<bdi class="figno">
+3
+</bdi>
+</a>
+<span class="fig-title">
+Connected
+Car
+</span>
+</figcaption>
+</figure>
+</section>
+</section>
+</section>
+<section id="sec-common-deployment-patterns" class="informative">
+<div class="header-wrapper">
+<h2 id="x5-common-deployment-patterns">
+<bdi class="secno">
+5.
+</bdi>
+Common
+Deployment
+Patterns
+</h2>
+<a class="self-link" href="#sec-common-deployment-patterns" aria-label="Permalink for Section 5.">
+</a>
+</div>
+<p>
+<em>
+This
+section
+is
+non-normative.
+</em>
+</p>
+<p>
+This
+section
+introduces
+common
+deployment
+patterns
+that
+illustrate
+how
+devices/things
+interact
+with
+controllers,
+other
+devices,
+agents
+and
+servers.
+In
+this
+section,
+we
+use
+the
+term
+<em>
+client
+role
+</em>
+as
+an
+initiator
+of
+a
+transport
+protocol,
+and
+the
+term
+<em>
+server
+role
+</em>
+as
+a
+passive
+component
+of
+a
+transport
+protocol.
+This
+does
+not
+imply
+prescribing
+a
+specific
+role
+on
+any
+system
+component.
+A
+device
+can
+be
+in
+a
+<em>
+client
+</em>
+and
+<em>
+server
+</em>
+role
+simultaneously.
+</p>
+<p>
+One
+example
+of
+this
+dual
+role
+is
+a
+sensor,
+that
+registers
+itself
+with
+a
+cloud
+service
+and
+regularly
+sends
+sensor
+readings
+to
+the
+cloud.
+In
+the
+response
+messages
+the
+cloud
+can
+adjust
+the
+transmission
+rate
+of
+the
+sensor's
+messages
+or
+select
+specific
+sensor
+attributes,
+that
+are
+to
+be
+transmitted
+in
+future
+messages.
+Since
+the
+sensor
+registers
+itself
+with
+the
+cloud
+and
+initiates
+connections,
+it
+is
+in
+the
+'client'
+role.
+However,
+since
+it
+also
+reacts
+to
+requests,
+that
+are
+transmitted
+in
+response
+messages,
+it
+also
+fulfills
+a
+'server'
+role.
+</p>
+<p>
+The
+following
+sections
+illustrate
+the
+roles,
+tasks,
+and
+use
+case
+patterns
+with
+increasing
+complexity.
+They
+are
+not
+exhaustive
+and
+are
+presented
+to
+motivate
+for
+the
+WoT
+architecture
+and
+building
+blocks
+that
+are
+defined
+in
+later
+sections
+of
+this
+specification.
+</p>
+<p>
+This
+section
+also
+makes
+use
+of
+the
+concept
+of
+a
+<a href= "#dfn-trusted-environment" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-trusted-environment-1">
+Trusted
+Environment
+</a>,
+which
+is
+a
+set
+of
+devices
+that
+allow
+relatively
+unrestricted
+access
+to
+one
+another.
+This
+is
+a
+common
+approach
+but
+carries
+some
+risks,
+which
+are
+discussed
+in
+section
+<a href= "#sec-security-consideration-trusted-environment-risks" class= "sec-ref">
+<bdi class="secno">
+10.4
+</bdi>
+Trusted
+Environment
+Risks
+</a>,
+along
+with
+mitigations
+of
+these
+risks.
+</p>
+<section id="telemetry">
+<div class="header-wrapper">
+<h3 id="x5-1-telemetry">
+<bdi class="secno">
+5.1
+</bdi>
+Telemetry
+</h3>
+<a class="self-link" href="#telemetry" aria-label= "Permalink for Section 5.1">
+</a>
+</div>
+<p>
+Telemetry
+is
+the
+monitoring
+of
+remote
+devices,
+which
+implies
+automatic
+transmission
+to,
+and
+processing
+of
+measurements
+and
+other
+data
+on
+a
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-consumer-5">
+Consumer
+</a>.
+Data
+may
+be
+transported
+over
+various
+communication
+channels,
+both
+wireless
+and
+wired.
+Examples
+include
+GSM
+networks,
+Bluetooth,
+WiFi,
+Ethernet,
+and
+other
+wired
+standards.
+</p>
+<p>
+Remote
+metering
+devices
+include
+one
+or
+multiple
+sensors,
+in
+some
+cases
+they
+also
+contain
+an
+actuator.
+In
+many
+cases
+the
+sensor
+data
+is
+transmitted
+at
+regular
+intervals,
+on
+a
+state
+change,
+or
+as
+a
+response
+to
+a
+request
+by
+the
+<a href="#dfn-consumer" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-6">
+Consumer
+</a>.
+</p>
+<p>
+Remote
+metering
+devices
+are
+frequently
+small
+embedded
+systems
+with
+very
+limited
+resources,
+i.e.
+Class-2
+or
+below.
+They
+may
+be
+battery
+powered
+and
+have
+to
+minimize
+power
+consumption
+through
+various
+measures,
+e.g.
+sleep
+modes.
+These
+devices
+will
+sleep
+most
+of
+the
+time
+and
+won't
+transmit
+any
+data
+to
+conserve
+energy.
+They
+only
+wake
+up
+on
+certain
+events
+(e.g.
+when
+a
+switch
+is
+toggled).
+When
+a
+device
+state
+changes,
+an
+event
+is
+sent
+to
+the
+consumer.
+After
+that
+the
+devices
+goes
+to
+sleep
+mode
+again.
+</p>
+<p>
+Typical
+user
+scenarios
+are
+monitoring
+of
+various
+assets,
+examples
+include
+smart
+cities,
+factories,
+fleets,
+environmental
+monitoring
+and
+health
+monitoring.
+Some
+deployments
+may
+require
+monitoring
+of
+a
+high
+number
+of
+geographically
+distributed
+assets,
+others
+only
+include
+a
+few
+devices,
+as
+in
+a
+smart
+home.
+A
+common
+pattern
+is
+the
+one-to-many
+relationship
+between
+a
+single
+<a href= "#dfn-consumer" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-7">
+Consumer
+</a>
+and
+multiple
+devices
+(
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-12">
+Things
+</a>
+).
+</p>
+</section>
+<section id="device-controllers">
+<div class="header-wrapper">
+<h3 id="x5-2-device-controllers">
+<bdi class="secno">
+5.2
+</bdi>
+Device
+Controllers
+</h3>
+<a class="self-link" href="#device-controllers" aria-label= "Permalink for Section 5.2">
+</a>
+</div>
+<p>
+A
+common
+deployment
+pattern
+is
+a
+local
+device
+controlled
+by
+a
+user-operated
+remote
+controller
+as
+depicted
+in
+<a href= "#smart-home-device" class="fig-ref" title="Device Control">
+Figure
+<bdi class="">
+4
+</bdi>
+</a>.
+</p>
+<p>
+A
+remote
+controller
+can
+access
+an
+electronic
+appliance
+through
+the
+local
+home
+network
+directly.
+In
+this
+case,
+the
+remote
+controller
+can
+be
+implemented
+by
+a
+browser
+or
+native
+application.
+</p>
+<p>
+In
+this
+pattern,
+at
+least
+one
+device
+like
+the
+electronic
+appliance
+has
+a
+server
+role
+that
+can
+accept
+a
+request
+from
+the
+other
+devices
+and
+responds
+to
+them,
+and
+sometimes
+initiates
+a
+mechanical
+action.
+The
+other
+device
+like
+the
+remote
+controller
+has
+a
+client
+role
+that
+can
+send
+a
+message
+with
+a
+request,
+like
+to
+read
+a
+sensor
+value
+or
+to
+turn
+on
+the
+device.
+Moreover,
+to
+emit
+a
+current
+state
+or
+event
+notification
+of
+a
+device,
+the
+device
+may
+have
+a
+client
+role
+that
+can
+send
+a
+message
+to
+another
+device,
+which
+has
+server
+roles.
+</p>
+<figure id="smart-home-device">
+<img src= "images/wot-use-cases/smart-home-device.png" srcset= "images/wot-use-cases/smart-home-device.svg" class= "wot-arch-diagram" alt="smart home device use case" />
+<figcaption>
+<a class="self-link" href="#smart-home-device">
+Figure
+<bdi class="figno">
+4
+</bdi>
+</a>
+<span class="fig-title">
+Device
+Control
+</span>
+</figcaption>
+</figure>
+</section>
+<section id="thing-to-thing">
+<div class="header-wrapper">
+<h3 id="x5-3-thing-to-thing">
+<bdi class="secno">
+5.3
+</bdi>
+Thing-to-Thing
+</h3>
+<a class="self-link" href="#thing-to-thing" aria-label= "Permalink for Section 5.3">
+</a>
+</div>
+<p>
+<a href="#smart-home-t2t" class="fig-ref" title= "Control Agent">
+Figure
+<bdi class="">
+5
+</bdi>
+</a>
+shows
+an
+example
+of
+a
+direct
+Thing-to-Thing
+interaction.
+The
+scenario
+is
+as
+follows:
+a
+sensor
+detects
+a
+change
+of
+the
+room
+condition,
+for
+example
+the
+temperature
+exceeding
+a
+threshold,
+and
+issues
+a
+control
+message
+like
+"turn
+on"
+to
+the
+electronic
+appliance.
+The
+sensor
+unit
+can
+issue
+some
+trigger
+messages
+to
+other
+devices.
+</p>
+<p>
+In
+this
+case,
+when
+two
+devices
+that
+have
+server
+roles
+are
+connected,
+at
+least
+one
+device
+must
+have
+also
+a
+client
+role
+that
+issues
+a
+message
+to
+the
+other
+to
+actuate
+or
+notify.
+</p>
+<figure id="smart-home-t2t">
+<img src= "images/wot-use-cases/smart-home-t2t.png" srcset= "images/wot-use-cases/smart-home-t2t.svg" class="wot-arch-diagram" alt="smart home t2t deployment scenario" />
+<figcaption>
+<a class="self-link" href="#smart-home-t2t">
+Figure
+<bdi class="figno">
+5
+</bdi>
+</a>
+<span class="fig-title">
+Control
+Agent
+</span>
+</figcaption>
+</figure>
+</section>
+<section id="remote-access">
+<div class="header-wrapper">
+<h3 id="x5-4-remote-access">
+<bdi class="secno">
+5.4
+</bdi>
+Remote
+Access
+</h3>
+<a class="self-link" href="#remote-access" aria-label= "Permalink for Section 5.4">
+</a>
+</div>
+<p>
+This
+deployment
+scenario
+contains
+a
+mobile
+remote
+controller
+(e.g.,
+on
+a
+smartphone)
+as
+shown
+in
+<a href="#smart-home-multi" class="fig-ref" title="Multiple Network Interfaces">
+Figure
+<bdi class="">
+6
+</bdi>
+</a>.
+The
+remote
+controller
+can
+switch
+between
+different
+network
+connections
+and
+protocols,
+e.g.,
+between
+a
+cellular
+network
+and
+a
+home
+network,
+which
+is
+using
+protocols
+such
+as
+Wi-Fi
+and
+Bluetooth.
+When
+the
+controller
+is
+in
+the
+home
+network
+it
+is
+a
+trusted
+device
+and
+no
+additional
+security
+or
+access
+control
+is
+required.
+When
+it
+is
+outside
+of
+the
+trusted
+network,
+additional
+access
+control
+and
+security
+mechanisms
+must
+be
+applied
+to
+ensure
+a
+trusted
+relationship.
+Note
+that
+in
+this
+scenario
+the
+network
+connectivity
+may
+change
+due
+to
+switching
+between
+different
+network
+access
+points
+or
+cellular
+base
+stations.
+</p>
+<p>
+In
+this
+pattern,
+the
+remote
+controller
+and
+the
+electronic
+appliance
+have
+a
+client
+and
+a
+server
+role
+as
+in
+the
+related
+scenario
+in
+<a href="#smart-home-device" class="fig-ref" title= "Device Control">
+Figure
+<bdi class="">
+4
+</bdi>
+</a>.
+</p>
+<figure id="smart-home-multi">
+<img src= "images/wot-use-cases/smart-home-multi.png" srcset= "images/wot-use-cases/smart-home-multi.svg" class= "wot-arch-diagram" alt= "smart home with multiple network interfaces" />
+<figcaption>
+<a class="self-link" href="#smart-home-multi">
+Figure
+<bdi class="figno">
+6
+</bdi>
+</a>
+<span class="fig-title">
+Multiple
+Network
+Interfaces
+</span>
+</figcaption>
+</figure>
+</section>
+<section id="smart-home-gateways">
+<div class="header-wrapper">
+<h3 id="x5-5-smart-home-gateways">
+<bdi class="secno">
+5.5
+</bdi>
+Smart
+Home
+Gateways
+</h3>
+<a class="self-link" href="#smart-home-gateways" aria-label= "Permalink for Section 5.5">
+</a>
+</div>
+<p>
+<a href="#smart-home-gateway" class="fig-ref" title= "Smart Home Gateway">
+Figure
+<bdi class="">
+7
+</bdi>
+</a>
+shows
+a
+deployment
+scenario
+of
+a
+<em>
+Smart
+Home
+Gateway
+</em>.
+The
+gateway
+is
+placed
+between
+a
+home
+network
+and
+the
+Internet.
+It
+manages
+electronic
+appliances
+inside
+the
+house
+and
+can
+receive
+commands
+from
+a
+remote
+controller
+over
+the
+Internet,
+e.g.,
+from
+a
+smartphone
+as
+in
+the
+previous
+scenario.
+It
+is
+also
+is
+a
+virtual
+representation
+of
+a
+device.
+The
+Smart
+Home
+Gateway
+typically
+offers
+proxy
+and
+firewall
+functionality.
+</p>
+<p>
+In
+this
+pattern,
+the
+home
+gateway
+has
+both
+a
+client
+and
+a
+server
+role.
+When
+the
+remote
+controller
+actuates
+the
+electronic
+appliance,
+it
+can
+connect
+to
+the
+electronic
+appliance
+in
+the
+client
+role
+and
+to
+the
+remote
+controller
+with
+the
+server
+role.
+When
+the
+electronic
+appliance
+emits
+a
+message
+to
+the
+remote
+controller,
+the
+gateway
+act
+as
+server
+roles
+for
+the
+electric
+appliance,
+and
+it
+act
+as
+client
+roles
+for
+the
+remote
+controller.
+</p>
+<figure id="smart-home-gateway">
+<img src= "images/wot-use-cases/smart-home-gateway.png" srcset= "images/wot-use-cases/smart-home-gateway.svg" class= "wot-arch-diagram" alt="smart home gateway use case" />
+<figcaption>
+<a class="self-link" href="#smart-home-gateway">
+Figure
+<bdi class="figno">
+7
+</bdi>
+</a>
+<span class="fig-title">
+Smart
+Home
+Gateway
+</span>
+</figcaption>
+</figure>
+</section>
+<section id="edge-devices">
+<div class="header-wrapper">
+<h3 id="x5-6-edge-devices">
+<bdi class="secno">
+5.6
+</bdi>
+Edge
+Devices
+</h3>
+<a class="self-link" href="#edge-devices" aria-label= "Permalink for Section 5.6">
+</a>
+</div>
+<p>
+An
+<em>
+Edge
+Device
+</em>
+or
+<em>
+Edge
+Gateway
+</em>
+is
+similar
+to
+a
+Smart
+Home
+Gateway.
+We
+use
+the
+term
+to
+indicate
+additional
+tasks
+that
+are
+carried
+out
+by
+the
+edge
+gateway.
+Whereas
+the
+home
+gateway
+in
+<a href="#edge-device" class="fig-ref" title= "Edge device">
+Figure
+<bdi class="">
+8
+</bdi>
+</a>
+primarily
+just
+bridges
+between
+the
+public
+and
+the
+trusted
+network,
+the
+edge
+device
+has
+local
+compute
+capabilities
+and
+typically
+bridges
+between
+different
+protocols.
+Edge
+devices
+are
+typically
+used
+in
+industrial
+solutions,
+where
+they
+can
+provide
+preprocessing,
+filtering
+and
+aggregation
+of
+data
+provided
+by
+connected
+devices
+and
+sensors.
+</p>
+<figure id="edge-device">
+<img src= "images/wot-use-cases/edge-device.png" srcset= "images/wot-use-cases/edge-device.svg" class="wot-arch-diagram" alt="edge device use case" />
+<figcaption>
+<a class="self-link" href="#edge-device">
+Figure
+<bdi class="figno">
+8
+</bdi>
+</a>
+<span class="fig-title">
+Edge
+device
+</span>
+</figcaption>
+</figure>
+</section>
+<section id="digital-twins">
+<div class="header-wrapper">
+<h3 id="x5-7-digital-twins">
+<bdi class="secno">
+5.7
+</bdi>
+Digital
+Twins
+</h3>
+<a class="self-link" href="#digital-twins" aria-label= "Permalink for Section 5.7">
+</a>
+</div>
+<p>
+A
+<em>
+Digital
+Twin
+</em>
+is
+a
+virtual
+representation,
+i.e.
+a
+model
+of
+a
+device
+or
+a
+group
+of
+devices
+that
+resides
+on
+a
+cloud
+server
+or
+edge
+device.
+It
+can
+be
+used
+to
+represent
+real-world
+devices
+which
+may
+not
+be
+continuously
+online,
+or
+to
+run
+simulations
+of
+new
+applications
+and
+services,
+before
+they
+get
+deployed
+to
+the
+real
+devices.
+</p>
+<figure id="digital-twin">
+<img src= "images/wot-use-cases/digital-twin.png" srcset= "images/wot-use-cases/digital-twin.svg" class="wot-arch-diagram" alt="digital twin use case" />
+<figcaption>
+<a class="self-link" href="#digital-twin">
+Figure
+<bdi class="figno">
+9
+</bdi>
+</a>
+<span class="fig-title">
+Digital
+Twin
+</span>
+</figcaption>
+</figure>
+<p>
+Digital
+twins
+can
+model
+a
+single
+device,
+or
+they
+can
+aggregate
+multiple
+devices
+in
+a
+virtual
+representation
+of
+the
+combined
+devices.
+</p>
+<figure id="digital-twin-multiple-devices">
+<img src= "images/wot-use-cases/digital-twin-multiple-devices.png" srcset= "images/wot-use-cases/digital-twin-multiple-devices.svg" class= "wot-arch-diagram" alt="digital twin multiple devices use case" />
+<figcaption>
+<a class="self-link" href= "#digital-twin-multiple-devices">
+Figure
+<bdi class= "figno">
+10
+</bdi>
+</a>
+<span class="fig-title">
+Digital
+Twin
+for
+Multiple
+Devices
+</span>
+</figcaption>
+</figure>
+<p>
+Digital
+twins
+can
+be
+realized
+in
+different
+ways,
+depending
+on
+whether
+a
+device
+is
+already
+connected
+to
+the
+cloud,
+or
+whether
+it
+is
+connected
+to
+a
+gateway,
+which
+itself
+is
+connected
+to
+the
+cloud.
+</p>
+<section id="cloud-connected-devices">
+<div class="header-wrapper">
+<h4 id="x5-7-1-cloud-connected-devices">
+<bdi class= "secno">
+5.7.1
+</bdi>
+Cloud
+Connected
+Devices
+</h4>
+<a class="self-link" href="#cloud-connected-devices" aria-label= "Permalink for Section 5.7.1">
+</a>
+</div>
+<p>
+<a href="#smart-home-cloud1" class="fig-ref" title= "Appliance Twin for a Cloud Connected Devices">
+Figure
+<bdi class= "">
+11
+</bdi>
+</a>
+shows
+an
+example
+where
+electronic
+appliances
+are
+connected
+directly
+to
+the
+cloud.
+The
+cloud
+mirrors
+the
+appliances
+and,
+acting
+as
+a
+digital
+twin,
+can
+receive
+commands
+from
+remote
+controllers
+(e.g.,
+a
+smartphone).
+Authorized
+controllers
+can
+be
+located
+anywhere,
+as
+the
+digital
+twin
+is
+globally
+reachable.
+</p>
+<figure id="smart-home-cloud1">
+<img src= "images/wot-use-cases/smart-home-cloud1a.png" srcset= "images/wot-use-cases/smart-home-cloud1a.svg" class= "wot-arch-diagram" alt="smart home cloud use case 1" />
+<figcaption>
+<a class="self-link" href="#smart-home-cloud1">
+Figure
+<bdi class="figno">
+11
+</bdi>
+</a>
+<span class="fig-title">
+Appliance
+Twin
+for
+a
+Cloud
+Connected
+Devices
+</span>
+</figcaption>
+</figure>
+</section>
+<section id="orchestration">
+<div class="header-wrapper">
+<h4 id="x5-7-2-orchestration">
+<bdi class="secno">
+5.7.2
+</bdi>
+Orchestration
+</h4>
+<a class="self-link" href="#orchestration" aria-label= "Permalink for Section 5.7.2">
+</a>
+</div>
+<p>
+Orchestration
+of
+devices
+and
+operation
+flows
+provides
+capabilities
+that
+go
+beyond
+the
+simple
+isolated
+usage
+of
+a
+device.
+An
+orchestrated
+set
+of
+devices
+can
+provide
+combined
+operations,
+that
+affect
+the
+state
+of
+multiple
+devices
+with
+a
+single
+operation.
+</p>
+<p>
+These
+operations
+combine
+individual
+operations
+into
+a
+combined
+operation
+flow,
+the
+flow
+may
+have
+several
+alternative
+paths,
+that
+are
+chosen
+based
+on
+some
+device
+state
+or
+property
+values.
+</p>
+<p>
+Orchestrated
+devices
+can
+be
+deployed
+in
+various
+topologies
+and
+can
+be
+connected
+via
+different
+networks.
+The
+system,
+that
+is
+built
+from
+these
+devices,
+can
+provide
+capabilities,
+that
+combine
+and
+exceed
+the
+capabilities
+of
+individual
+devices.
+</p>
+<p>
+A
+typical
+orchestration
+example
+is
+a
+smart
+home,
+where
+various
+sensors
+(temperature,
+occupancy,
+humidity,
+light,
+air
+quality,
+door
+sensors)
+are
+interworking
+and
+provide
+operation
+flows
+for
+situations
+like
+entering
+or
+leaving
+the
+house,
+morning/evening
+routine,
+adjusting
+light
+and
+temperature
+based
+on
+presence,
+and
+much
+more.
+</p>
+</section>
+<section id="legacy-devices">
+<div class="header-wrapper">
+<h4 id="x5-7-3-legacy-devices">
+<bdi class="secno">
+5.7.3
+</bdi>
+Legacy
+Devices
+</h4>
+<a class="self-link" href="#legacy-devices" aria-label= "Permalink for Section 5.7.3">
+</a>
+</div>
+<p>
+<a href="#smart-home-cloud2" class="fig-ref" title= "A Digital Twin for a Legacy Device">
+Figure
+<bdi class= "">
+12
+</bdi>
+</a>
+shows
+an
+example
+where
+legacy
+electronic
+appliances
+are
+not
+directly
+connected
+to
+the
+cloud.
+Here,
+a
+gateway
+is
+needed
+to
+relay
+the
+connection.
+The
+gateway
+works
+as:
+</p>
+<ul>
+<li>
+integrator
+of
+a
+variety
+of
+legacy
+communication
+protocols
+both
+in
+the
+physical
+and
+logical
+view
+</li>
+<li>
+firewall
+toward
+the
+Internet
+</li>
+<li>
+privacy
+filter
+which
+substitutes
+real
+image
+and/or
+speech,
+and
+logs
+data
+locally
+</li>
+<li>
+local
+agent
+in
+case
+the
+network
+connection
+is
+interrupted
+</li>
+<li>
+emergency
+services
+running
+locally
+when
+fire
+alarms
+and
+similar
+events
+occur
+</li>
+</ul>
+<p>
+The
+cloud
+mirrors
+the
+gateway
+with
+all
+connected
+appliances
+and
+acts
+as
+a
+digital
+twin
+that
+manages
+them
+in
+the
+cloud
+in
+conjunction
+with
+the
+gateway.
+Furthermore,
+the
+cloud
+can
+receive
+commands
+from
+remote
+controllers
+(e.g.,
+a
+smartphone),
+which
+can
+be
+located
+anywhere.
+</p>
+<figure id="smart-home-cloud2">
+<img src= "images/wot-use-cases/smart-home-cloud2.png" srcset= "images/wot-use-cases/smart-home-cloud2.svg" class= "wot-arch-diagram" alt="smart home cloud use case 2" />
+<figcaption>
+<a class="self-link" href="#smart-home-cloud2">
+Figure
+<bdi class="figno">
+12
+</bdi>
+</a>
+<span class="fig-title">
+A
+Digital
+Twin
+for
+a
+Legacy
+Device
+</span>
+</figcaption>
+</figure>
+</section>
+</section>
+<section id="multi-cloud">
+<div class="header-wrapper">
+<h3 id="x5-8-multi-cloud">
+<bdi class="secno">
+5.8
+</bdi>
+Multi-Cloud
+</h3>
+<a class="self-link" href="#multi-cloud" aria-label= "Permalink for Section 5.8">
+</a>
+</div>
+<p>
+Typical
+IoT
+deployments
+consist
+of
+multiple
+(thousands)
+of
+devices.
+Without
+a
+standardized
+mechanism,
+the
+management
+of
+firmware
+updates
+for
+specific
+clouds
+require
+a
+lot
+of
+effort
+and
+hinders
+wider
+scale
+IoT
+adoption.
+</p>
+<p>
+The
+primary
+benefit
+of
+a
+standardized
+mechanism
+for
+describing
+devices
+and
+device
+types
+is
+the
+capability
+of
+deploying
+devices
+to
+different
+cloud
+environments
+without
+the
+need
+of
+doing
+customization
+at
+device
+software
+/
+firmware
+level,
+i.e.,
+installing
+cloud
+specific
+code
+to
+a
+device.
+This
+implies
+that
+the
+solution
+is
+flexible
+enough
+to
+describe
+devices
+in
+a
+way
+that
+allows
+on-boarding
+and
+using
+devices
+in
+multiple
+IoT
+cloud
+environments.
+</p>
+<p>
+This
+drives
+adoption
+of
+Web
+of
+Things
+devices,
+since
+it
+enables
+easy
+usage
+of
+new
+devices
+in
+an
+existing
+deployment,
+as
+well
+as
+migration
+of
+existing
+devices
+from
+one
+cloud
+to
+the
+other.
+</p>
+</section>
+<section id="virtual-thing">
+<div class="header-wrapper">
+<h3 id="x5-9-virtual-things">
+<bdi class="secno">
+5.9
+</bdi>
+Virtual
+Things
+</h3>
+<a class="self-link" href="#virtual-thing" aria-label= "Permalink for Section 5.9">
+</a>
+</div>
+<p>
+A
+<a href="#dfn-virtual-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-virtual-thing-4">
+Virtual
+Thing
+</a>
+is
+a
+<a href="#dfn-service" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-service-5">
+Service
+</a>
+that
+acts
+as
+a
+placeholder
+for
+one
+or
+more
+other
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-13">
+Things
+</a>
+which
+provides
+an
+interface
+to
+its
+<a href="#dfn-consumer" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-consumer-8">
+consumers
+</a>.
+</p>
+<p>
+In
+a
+simple
+case
+it
+is
+an
+interface
+abstraction,
+which
+defines
+a
+common
+interface
+to
+devices,
+where
+it
+is
+possible
+to
+replace
+a
+device
+model
+with
+another
+one
+without
+changing
+the
+consumer.
+</p>
+<p>
+In
+a
+more
+complex
+scenario,
+a
+<a href="#dfn-virtual-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-virtual-thing-5">
+Virtual
+Thing
+</a>
+provides
+a
+single
+interface
+for
+multiple
+devices,
+and
+provides
+a
+higher
+level
+of
+operations
+to
+its
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-consumer-9">
+Consumers
+</a>.
+Individual
+devices
+can
+be
+replaced,
+new
+operations
+can
+be
+provided
+via
+software
+upgrades.
+</p>
+<p>
+A
+Virtual
+Thing
+will
+often
+act
+as
+an
+<a href="#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-2">
+Intermediary
+</a>.
+Examples
+include
+<a href="#dfn-shadow" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-shadow-4">
+Shadows
+</a>
+and
+<a href="#dfn-digital-twin" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-digital-twin-3">
+Digital
+Twins
+</a>.
+</p>
+</section>
+<section id="sec-cross-domain-collaboration">
+<div class="header-wrapper">
+<h3 id="x5-10-cross-domain-collaboration">
+<bdi class= "secno">
+5.10
+</bdi>
+Cross-domain
+Collaboration
+</h3>
+<a class="self-link" href="#sec-cross-domain-collaboration" aria-label="Permalink for Section 5.10">
+</a>
+</div>
+<p>
+<a href="#cross-domain" class="fig-ref" title= "Cross-domain collaboration">
+Figure
+<bdi class="">
+13
+</bdi>
+</a>
+show
+an
+example
+of
+a
+cross-domain
+collaboration.
+In
+this
+case,
+each
+system
+involves
+other
+systems
+in
+other
+domains,
+such
+as
+Smart
+Factory
+with
+Smart
+City,
+Smart
+City
+with
+Smart
+Home.
+This
+type
+of
+system
+is
+called
+"Symbiotic"
+ecosystem,
+as
+shown
+in
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-iec-fotf" title="Factory of the future">
+IEC-FOTF
+</a>
+</cite>
+].
+There
+are
+two
+collaboration
+models:
+direct
+collaboration
+and
+indirect
+collaboration.
+In
+the
+direct
+collaboration
+model,
+systems
+exchange
+information
+directly
+with
+each
+other
+in
+a
+peer-to-peer
+manner.
+In
+the
+indirect
+collaboration,
+systems
+exchange
+information
+via
+some
+collaboration
+platform.
+In
+order
+to
+maintain
+and
+continue
+this
+collaboration,
+each
+system
+provides
+the
+metadata
+of
+their
+capabilities
+and
+interfaces
+and
+adapts
+itself
+to
+others.
+</p>
+<figure id="cross-domain">
+<img src= "images/wot-use-cases/cross-domain-direct.png" srcset= "images/wot-use-cases/cross-domain-direct.svg" class= "wot-arch-diagram" alt="cross domain direct use case" />
+<img src= "images/wot-use-cases/cross-domain-indirect.png" srcset= "images/wot-use-cases/cross-domain-indirect.svg" class= "wot-arch-diagram" alt="cross domain indirect use case" />
+<figcaption>
+<a class="self-link" href="#cross-domain">
+Figure
+<bdi class="figno">
+13
+</bdi>
+</a>
+<span class= "fig-title">
+Cross-domain
+collaboration
+</span>
+</figcaption>
+</figure>
+</section>
+<section id="sec-system-integration">
+<div class="header-wrapper">
+<h3 id="x5-11-system-integration">
+<bdi class="secno">
+5.11
+</bdi>
+System
+Integration
+</h3>
+<a class="self-link" href="#sec-system-integration" aria-label= "Permalink for Section 5.11">
+</a>
+</div>
+<p>
+The
+previous
+section
+described
+various
+architecture
+patterns.
+In
+these
+patterns,
+some
+functional
+entities
+such
+as
+the
+devices
+including
+the
+legacy
+devices,
+controllers,
+gateways
+and
+cloud
+servers
+are
+located
+at
+physical
+locations
+such
+as
+inside
+building,
+outside
+buildings,
+and
+data
+centers.
+<a href="#system-integration" class="fig-ref" title="System integration">
+Figure
+<bdi class= "">
+14
+</bdi>
+</a>
+is
+an
+overview
+that
+shows
+the
+combinations
+and
+communication
+paths
+of
+these
+entities.
+</p>
+<p>
+In
+a
+transport
+protocol
+layer,
+each
+entity
+arbitrarily
+selects
+a
+suitable
+role
+for
+communications.
+For
+example,
+a
+device
+may
+act
+as
+a
+server
+when
+the
+device
+provides
+a
+service
+to
+indefinite
+number
+of
+applications.
+On
+the
+other
+hand,
+if
+a
+device
+has
+limited
+or
+intermittent
+network
+connectivity,
+they
+may
+act
+as
+a
+client
+and
+actively
+send
+message
+to
+an
+application
+when
+network
+is
+available.
+Regardless
+of
+this,
+in
+application
+layer,
+an
+application
+sees
+that
+a
+device
+provides
+abstract
+interfaces
+to
+interact
+and
+the
+application
+can
+interact
+with
+the
+device
+using
+their
+abstract
+interfaces.
+</p>
+<figure id="system-integration">
+<img src= "images/system-integration.png" srcset= "images/system-integration.svg" class="wot-arch-diagram" alt= "system integration" />
+<figcaption>
+<a class="self-link" href="#system-integration">
+Figure
+<bdi class="figno">
+14
+</bdi>
+</a>
+<span class="fig-title">
+System
+integration
+</span>
+</figcaption>
+</figure>
+</section>
+</section>
+<section id="sec-wot-architecture">
+<div class="header-wrapper">
+<h2 id="x6-abstract-wot-system-architecture">
+<bdi class= "secno">
+6.
+</bdi>
+Abstract
+WoT
+System
+Architecture
+</h2>
+<a class="self-link" href="#sec-wot-architecture" aria-label= "Permalink for Section 6.">
+</a>
+</div>
+<p>
+<em>
+This
+section
+is
+normative.
+</em>
+</p>
+<p>
+To
+address
+the
+requirements
+and
+use
+cases
+that
+were
+gathered
+in
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-wot-use-cases-requirements" title= "Web of Things (WoT) Use Cases and Requirements">
+WOT-USE-CASES-REQUIREMENTS
+</a>
+</cite>
+]
+the
+Web
+of
+Things
+(WoT)
+builds
+on
+top
+of
+the
+concept
+of
+<a href= "#dfn-web-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-web-thing-1">
+Web
+Things
+</a>
+–
+usually
+simply
+called
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-14">
+Things
+</a>
+–
+that
+can
+be
+used
+by
+so-called
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-consumer-10">
+Consumers
+</a>.
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-11">
+Consumers
+</a>
+can
+interact
+with
+a
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-15">
+Thing
+</a>
+directly,
+or
+they
+use
+<a href= "#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-3">
+intermediaries
+</a>
+for
+indirect
+communication.
+</p>
+<p>
+These
+concepts
+are
+applicable
+for
+the
+various
+application
+domains
+of
+section
+<a href="#sec-application-domains" class= "sec-ref">
+<bdi class="secno">
+4.
+</bdi>
+Application
+Domains
+</a>.
+</p>
+<p>
+This
+section
+provides
+the
+background
+and
+normative
+assertions
+to
+define
+the
+overall
+<abbr title= "World Wide Web Consortium">
+W3C
+</abbr>
+Web
+of
+Things
+architecture.
+</p>
+<p>
+As
+the
+Web
+of
+Things
+addresses
+stakeholders
+from
+different
+domains,
+certain
+aspects
+of
+Web
+technology
+are
+explained
+in
+more
+detail,
+in
+particular
+the
+concept
+of
+hypermedia.
+</p>
+<section id="sec-architecture-overview">
+<div class="header-wrapper">
+<h3 id="x6-1-fundamental-concepts">
+<bdi class="secno">
+6.1
+</bdi>
+Fundamental
+Concepts
+</h3>
+<a class="self-link" href="#sec-architecture-overview" aria-label= "Permalink for Section 6.1">
+</a>
+</div>
+<p>
+This
+section
+introduces
+the
+fundamental
+concepts
+of
+the
+Web
+of
+Things.
+It
+introduces
+the
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-16">
+Thing
+</a>
+abstraction
+that
+is
+described
+with
+<a href="#dfn-thing-description" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-description-11">
+Thing
+Descriptions
+</a>
+and
+<a href="#dfn-wot-thing-model" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-wot-thing-model-2">
+Thing
+Models
+</a>,
+which
+then
+can
+be
+used
+by
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-12">
+Consumers
+</a>.
+</p>
+<p>
+A
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-17">
+Thing
+</a>
+is
+an
+abstraction
+of
+a
+physical
+or
+virtual
+entity
+(e.g.,
+a
+device
+or
+a
+room)
+and
+is
+described
+by
+standardized
+metadata.
+A
+<a href="#dfn-consumer" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-13">
+Consumer
+</a>
+is
+an
+entity
+that
+can
+read
+and
+interpret
+the
+standardized
+metadata
+for
+a
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-18">
+Thing
+</a>
+in
+order
+to
+communicate
+with
+that
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-19">
+Thing
+</a>.
+</p>
+<p>
+The
+<a href="#dfn-wot-thing-description" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-thing-description-3">
+WoT
+Thing
+Description
+</a>
+(TD)
+is
+a
+standardized,
+machine-readable
+metadata
+representation
+format
+that
+allows
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-14">
+Consumers
+</a>
+to
+discover
+and
+interpret
+the
+capabilities
+of
+a
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-20">
+Thing
+</a>
+(through
+semantic
+annotations)
+and
+to
+adapt
+to
+different
+implementations
+(e.g.,
+different
+protocols
+or
+data
+structures)
+when
+interacting
+with
+a
+<a href="#dfn-thing" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-thing-21">
+Thing
+</a>,
+thereby
+enabling
+interoperability
+across
+different
+<a href="#dfn-iot-platform" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-iot-platform-1">
+IoT
+platforms
+</a>,
+i.e.,
+different
+ecosystems
+and
+standards.
+The
+WoT
+<a href="#dfn-wot-thing-model" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-thing-model-3">
+Thing
+Model
+</a>
+(TM)
+is
+likewise
+a
+standardized,
+machine-readable
+metadata
+representation
+format
+for
+describing
+<em>
+classes
+</em>
+of
+<a href="#dfn-thing" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-22">
+Things
+</a>,
+such
+as
+devices
+of
+a
+product
+line
+with
+common
+capabilities.
+</p>
+<figure id="consumer-thing">
+<img src= "images/architecture/consumer-thing.png" srcset= "images/architecture/consumer-thing.svg" class="wot-arch-diagram" alt="consumer thing" />
+<figcaption>
+<a class="self-link" href="#consumer-thing">
+Figure
+<bdi class="figno">
+15
+</bdi>
+</a>
+<span class= "fig-title">
+Consumer-Thing
+interaction
+</span>
+</figcaption>
+</figure>
+<p>
+A
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-23">
+Thing
+</a>
+can
+also
+be
+the
+abstraction
+of
+a
+<em>
+virtual
+entity
+</em>.
+A
+virtual
+entity
+is
+the
+composition
+of
+one
+or
+more
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-24">
+Things
+</a>
+(e.g.,
+a
+room
+consisting
+of
+several
+sensors
+and
+actuators).
+One
+option
+for
+the
+composition
+is
+to
+provide
+a
+single,
+consolidated
+<a href= "#dfn-wot-thing-description" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-wot-thing-description-4">
+WoT
+Thing
+Description
+</a>
+that
+contains
+the
+combination
+of
+capabilities
+for
+the
+virtual
+entity.
+In
+cases
+where
+the
+composition
+is
+rather
+complex,
+its
+<a href="#dfn-td" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-td-2">
+TD
+</a>
+may
+<em>
+link
+</em>
+to
+hierarchical
+sub-Things
+within
+the
+composition.
+The
+main
+<a href= "#dfn-td" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-td-3">
+TD
+</a>
+acts
+as
+entry
+point
+and
+only
+contain
+general
+metadata
+and
+potentially
+overarching
+capabilities.
+This
+allows
+grouping
+of
+certain
+aspects
+of
+more
+complex
+<a href= "#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-25">
+Things
+</a>.
+</p>
+<section id="metadata">
+<div class="header-wrapper">
+<h4 id="x6-1-1-metadata">
+<bdi class="secno">
+6.1.1
+</bdi>
+Metadata
+</h4>
+<a class="self-link" href="#metadata" aria-label= "Permalink for Section 6.1.1">
+</a>
+</div>
+<p>
+The
+WoT
+architecture
+provides
+metadata
+formats
+to
+describe
+both
+specific
+<em>
+instances
+</em>
+of
+<a href="#dfn-thing" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-26">
+Things
+</a>
+and
+<em>
+classes
+</em>
+of
+<a href= "#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-27">
+Things
+</a>.
+The
+metadata
+format
+for
+<em>
+instances
+</em>
+is
+called
+<a href="#dfn-thing-description" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-description-12">
+Thing
+Description
+</a>
+while
+that
+for
+<em>
+classes
+</em>
+is
+called
+<a href="#dfn-wot-thing-model" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-thing-model-4">
+Thing
+Model
+</a>.
+</p>
+<section id="metadata-thing-descriptions">
+<div class="header-wrapper">
+<h5 id="x6-1-1-1-thing-descriptions">
+<bdi class= "secno">
+6.1.1.1
+</bdi>
+Thing
+Descriptions
+</h5>
+<a class="self-link" href="#metadata-thing-descriptions" aria-label="Permalink for Section 6.1.1.1">
+</a>
+</div>
+<p>
+A
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-28">
+Thing
+</a>
+instance
+is
+described
+by
+standardized
+metadata.
+<span class="rfc2119-assertion" id= "arch-td-metadata">
+In
+<abbr title= "World Wide Web Consortium">
+W3C
+</abbr>
+WoT,
+the
+description
+metadata
+for
+a
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-29">
+Thing
+</a>
+instance
+<em class="rfc2119">
+MUST
+</em>
+be
+available
+as
+a
+<a href= "#dfn-wot-thing-description" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-wot-thing-description-5">
+WoT
+Thing
+Description
+</a>
+(TD)
+[
+<cite>
+<a class="bibref" data-link-type= "biblio" href="#bib-wot-thing-description" title= "Web of Things (WoT) Thing Description 1.1">
+WOT-THING-DESCRIPTION
+</a>
+</cite>
+].
+</span>
+The
+format
+can
+be
+processed
+either
+through
+classic
+JSON
+libraries
+or
+a
+JSON-LD
+processor,
+as
+the
+underlying
+information
+model
+is
+graph-based
+and
+its
+serialization
+compatible
+with
+JSON-LD
+1.1
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-json-ld11" title="JSON-LD 1.1">
+JSON-LD11
+</a>
+</cite>
+].
+The
+use
+of
+a
+JSON-LD
+processor
+for
+processing
+a
+TD
+additionally
+enables
+semantic
+processing
+including
+transformation
+to
+RDF
+triples,
+semantic
+inference
+and
+accomplishing
+tasks
+given
+based
+on
+ontological
+terms,
+which
+would
+make
+<a href="#dfn-consumer" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-15">
+Consumers
+</a>
+behave
+more
+autonomous.
+A
+<a href="#dfn-td" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-td-4">
+TD
+</a>
+is
+instance-specific
+(i.e.,
+describes
+an
+individual
+Thing,
+not
+types
+of
+Things)
+and
+is
+the
+default
+external,
+textual
+(Web)
+representation
+of
+a
+<a href="#dfn-thing" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-30">
+Thing
+</a>.
+<span class="rfc2119-assertion" id="arch-other-thing-representations">
+There
+<em class= "rfc2119">
+MAY
+</em>
+be
+other
+representations
+of
+a
+<a href= "#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-31">
+Thing
+</a>
+such
+as
+an
+HTML-based
+user
+interface,
+simply
+an
+image
+of
+the
+physical
+entity,
+or
+even
+non-Web
+representations
+in
+closed
+systems.
+</span>
+<span class= "rfc2119-assertion" id="arch-td-mandatory">
+To
+be
+considered
+a
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-32">
+Thing
+</a>,
+however,
+at
+least
+one
+<a href= "#dfn-td" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-td-5">
+TD
+</a>
+representation
+<em class= "rfc2119">
+MUST
+</em>
+be
+available.
+</span>
+</p>
+</section>
+<section id="metadata-thing-models">
+<div class="header-wrapper">
+<h5 id="x6-1-1-2-thing-models">
+<bdi class="secno">
+6.1.1.2
+</bdi>
+Thing
+Models
+</h5>
+<a class="self-link" href="#metadata-thing-models" aria-label= "Permalink for Section 6.1.1.2">
+</a>
+</div>
+<p>
+A
+<a href="#dfn-wot-thing-model" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-thing-model-5">
+Thing
+Model
+</a>
+can
+be
+used
+to
+describe
+common
+capabilities
+that
+are
+available
+for
+a
+set
+of
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-33">
+Things
+</a>,
+for
+example,
+for
+a
+large
+number
+of
+devices
+in
+a
+product
+line.
+In
+this
+case
+the
+<a href="#dfn-wot-thing-model" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-thing-model-6">
+Thing
+Model
+</a>
+defines
+the
+common
+capabilities
+of
+all
+devices
+in
+the
+product
+line,
+but
+omits
+information
+specific
+to
+a
+particular
+device.
+</p>
+<p>
+A
+<a href="#dfn-wot-thing-model" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-thing-model-7">
+Thing
+Model
+</a>
+may
+also
+be
+used
+when
+complete
+information
+for
+an
+instance
+is
+not
+available
+or
+is
+not
+necessary.
+For
+example,
+some
+IoT
+ecosystems
+implicitly
+handle
+communication
+separately.
+In
+such
+a
+case,
+a
+fully
+detailed
+<a href="#dfn-thing-description" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-description-13">
+Thing
+Description
+</a>,
+e.g.
+with
+communication
+metadata,
+is
+not
+necessary.
+Communication
+metadata
+may
+also
+not
+available
+at
+the
+beginning
+of
+a
+Thing
+lifecycle
+phase,
+since
+a
+new
+entity
+has
+not
+yet
+been
+deployed
+(e.g.
+the
+IP
+address
+is
+not
+yet
+known).
+</p>
+<p>
+A
+<a href="#dfn-wot-thing-model" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-thing-model-8">
+Thing
+Model
+</a>
+is
+used
+to
+define
+the
+basic
+information
+model
+of
+a
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-34">
+Thing
+</a>
+to
+address
+such
+kind
+of
+scenarios.
+The
+<a href="#dfn-wot-thing-model" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-thing-model-9">
+Thing
+Model
+</a>
+can
+be
+seen
+as
+a
+template
+for
+<a href= "#dfn-thing-description" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-description-14">
+Thing
+Descriptions
+</a>,
+however,
+that
+have
+less
+restriction
+as
+defined
+in
+sections
+"TD
+Information
+Model"
+and
+"Representation
+Format"
+of
+the
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-wot-thing-description" title= "Web of Things (WoT) Thing Description 1.1">
+WOT-THING-DESCRIPTION
+</a>
+</cite>
+].
+Typically
+<a href="#dfn-wot-thing-model" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-thing-model-10">
+Thing
+Model
+</a>
+examples
+does
+not
+contain
+any
+instance-specific
+information
+such
+as
+protocol
+specific
+data
+like
+IP
+addresses.
+However,
+instead
+of
+having,
+e.g.,
+concrete
+URLs,
+<a href= "#dfn-wot-thing-model" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-thing-model-11">
+Thing
+Model
+</a>
+allows
+the
+usage
+of
+URL
+templates.
+</p>
+<figure id="thing-model">
+<img src= "images/architecture/thing_model_td.png" srcset= "images/architecture/thing_model_td.svg" class="wot-arch-diagram" alt="Thing Model" />
+<figcaption>
+<a class="self-link" href="#thing-model">
+Figure
+<bdi class="figno">
+16
+</bdi>
+</a>
+<span class="fig-title">
+Thing
+Model
+and
+its
+relation
+to
+the
+Thing
+Description
+</span>
+</figcaption>
+</figure>
+<p>
+The
+Thing
+Model
+enables:
+</p>
+<ul>
+<li>
+onboarding
+and
+management
+of
+multiple
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-35">
+Thing
+</a>
+models,
+e.g.,
+by
+a
+cloud
+service.
+</li>
+<li>
+simulation
+of
+devices/
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-36">
+Things
+</a>
+that
+have
+not
+yet
+been
+developed.
+</li>
+<li>
+developing
+common
+applications
+across
+devices
+from
+different
+manufacturers
+that
+share
+a
+common
+<a href="#dfn-wot-thing-model" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-thing-model-12">
+Thing
+model
+</a>.
+</li>
+<li>
+combining
+multiple
+models
+into
+a
+<a href="#dfn-thing" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-37">
+Thing
+</a>.
+</li>
+<li>
+implementation
+support
+of
+a
+concrete
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-38">
+Thing
+</a>.
+</li>
+</ul>
+<p>
+The
+<a href="#dfn-wot-thing-model" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-thing-model-13">
+Thing
+Model
+</a>
+is
+a
+logical
+description
+of
+the
+interface
+and
+possible
+interaction
+with
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-39">
+Thing
+</a>
+'s
+<a href= "#dfn-property" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-property-2">
+Properties
+</a>,
+<a href="#dfn-action" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-action-2">
+Actions
+</a>,
+and
+<a href="#dfn-event" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-event-2">
+Events
+</a>,
+however
+it
+does
+not
+contain
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-40">
+Thing
+</a>
+instance-specific
+information,
+such
+as
+concrete
+protocol
+usage
+(e.g.,
+IP
+address),
+or
+even
+a
+serial
+number
+and
+GPS
+location.
+However,
+Thing
+Models
+allows
+to
+include,
+e.g.,
+security
+schemes
+if
+they
+apply
+to
+the
+entire
+class
+of
+instances
+the
+model
+describes.
+They
+might
+have
+URLs
+(e.g.,
+like
+token
+servers)
+that
+might
+need
+to
+be
+omitted
+or
+parameterized
+(with
+templates)
+although
+in
+a
+lot
+of
+cases
+these
+might
+also
+be
+given.
+</p>
+<p>
+A
+<a href="#dfn-wot-thing-model" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-thing-model-14">
+Thing
+Model
+</a>
+can
+be
+serialized
+in
+the
+same
+JSON-based
+format
+as
+a
+Thing
+Description
+which
+also
+allows
+JSON-LD
+processing.
+Note
+that
+a
+<a href="#dfn-wot-thing-model" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-wot-thing-model-15">
+Thing
+Model
+</a>
+cannot
+be
+validated
+in
+the
+same
+way
+as
+<a href="#dfn-thing-description" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-description-15">
+Thing
+Description
+</a>
+instances,
+since
+not
+all
+mandatory
+terms
+of
+a
+<a href="#dfn-thing-description" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-description-16">
+Thing
+Description
+</a>
+are
+required
+for
+a
+<a href="#dfn-wot-thing-model" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-thing-model-16">
+Thing
+Model
+</a>.
+missing
+mandatory
+terms.
+</p>
+</section>
+</section>
+<section id="links">
+<div class="header-wrapper">
+<h4 id="x6-1-2-links">
+<bdi class="secno">
+6.1.2
+</bdi>
+Links
+</h4>
+<a class="self-link" href="#links" aria-label= "Permalink for Section 6.1.2">
+</a>
+</div>
+</section>
+<p>
+Links
+can
+represent
+relationships
+between
+things,
+between
+things
+and
+thing
+models,
+and
+between
+thing
+models.
+Linking
+does
+not
+only
+apply
+to
+hierarchical
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-41">
+Things
+</a>,
+but
+also
+to
+relations
+between
+Things
+and
+other
+resources
+in
+general.
+Link
+relation
+types
+express
+how
+Things
+relate,
+for
+instance,
+a
+switch
+controlling
+a
+light
+or
+a
+room
+monitored
+by
+a
+motion
+sensor.
+Other
+resources
+related
+to
+a
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-42">
+Thing
+</a>
+can
+be
+documentation
+manuals,
+catalogs
+for
+spare
+parts,
+CAD
+files,
+a
+graphical
+UI,
+or
+any
+other
+document
+on
+the
+Web.
+Overall,
+Web
+linking
+among
+Things
+makes
+the
+Web
+of
+Things
+navigable,
+for
+both
+humans
+and
+machines.
+This
+can
+be
+further
+facilitated
+by
+providing
+<a href="#dfn-wot-thing-description-directory" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-thing-description-directory-5">
+Thing
+Description
+Directories
+</a>
+that
+manage
+a
+catalog
+of
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-43">
+Things
+</a>,
+usually
+by
+caching
+their
+TD
+representation.
+</p>
+<p>
+In
+summary,
+<span class="rfc2119-assertion" id= "arch-td-linking">
+<a href="#dfn-wot-thing-description" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-thing-description-6">
+WoT
+Thing
+Descriptions
+</a>
+and
+<a href="#dfn-wot-thing-model" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-thing-model-17">
+WoT
+Thing
+Models
+</a>
+<em class="rfc2119">
+MAY
+</em>
+link
+to
+other
+<a href= "#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-44">
+Things
+</a>,
+<a href="#dfn-wot-thing-model" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-thing-model-18">
+WoT
+Thing
+Models
+</a>,
+and
+other
+resources
+on
+the
+Web
+to
+form
+a
+Web
+of
+Things.
+</span>
+</p>
+<figure id="linked-things">
+<img src= "images/architecture/linked-things.png" srcset= "images/architecture/linked-things.svg" class="wot-arch-diagram" alt="linked things" />
+<figcaption>
+<a class="self-link" href="#linked-things">
+Figure
+<bdi class="figno">
+17
+</bdi>
+</a>
+<span class="fig-title">
+Linked
+Things
+</span>
+</figcaption>
+</figure>
+<p>
+<span class="rfc2119-assertion" id="arch-networked">
+Things
+<em class="rfc2119">
+MUST
+</em>
+be
+hosted
+on
+networked
+system
+components
+with
+a
+software
+stack
+to
+realize
+interaction
+through
+a
+network-facing
+interface,
+the
+<a href="#dfn-wot-interface" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-interface-1">
+WoT
+Interface
+</a>
+of
+a
+<a href= "#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-45">
+Thing
+</a>.
+</span>
+One
+example
+of
+this
+is
+an
+HTTP
+server
+running
+on
+an
+embedded
+device
+with
+sensors
+and
+actuators
+interfacing
+the
+physical
+entity
+behind
+the
+<a href= "#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-46">
+Thing
+</a>
+abstraction.
+However,
+<abbr title= "World Wide Web Consortium">
+W3C
+</abbr>
+WoT
+does
+not
+mandate
+where
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-47">
+Things
+</a>
+are
+hosted;
+it
+can
+be
+on
+the
+IoT
+device
+directly,
+an
+<a href="#dfn-edge-device" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-edge-device-1">
+Edge
+device
+</a>
+such
+as
+a
+gateway,
+or
+the
+cloud.
+</p>
+<p>
+A
+typical
+deployment
+challenge
+is
+a
+scenario
+where
+local
+networks
+are
+not
+reachable
+from
+the
+Internet,
+usually
+because
+of
+IPv4
+Network
+Address
+Translation
+(NAT)
+or
+firewall
+devices.
+To
+remedy
+this
+situation,
+<abbr title= "World Wide Web Consortium">
+W3C
+</abbr>
+WoT
+allows
+for
+<a href= "#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-4">
+Intermediaries
+</a>
+between
+<a href= "#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-48">
+Things
+</a>
+and
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-16">
+Consumers
+</a>.
+</p>
+<section id="intermediaries">
+<div class="header-wrapper">
+<h4 id="x6-1-3-intermediaries">
+<bdi class="secno">
+6.1.3
+</bdi>
+Intermediaries
+</h4>
+<a class="self-link" href="#intermediaries" aria-label= "Permalink for Section 6.1.3">
+</a>
+</div>
+</section>
+<p>
+<a href="#dfn-intermediary" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-intermediary-5">
+Intermediaries
+</a>
+can
+act
+as
+proxies
+for
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-49">
+Things
+</a>,
+where
+the
+<a href="#dfn-intermediary" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-intermediary-6">
+Intermediary
+</a>
+has
+a
+<a href="#dfn-wot-thing-description" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-thing-description-7">
+WoT
+Thing
+Description
+</a>
+similar
+to
+the
+original
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-50">
+Thing
+</a>,
+but
+which
+points
+to
+the
+<a href= "#dfn-wot-interface" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-interface-2">
+WoT
+Interface
+</a>
+provided
+by
+the
+<a href="#dfn-intermediary" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-intermediary-7">
+Intermediary
+</a>.
+<a href= "#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-8">
+Intermediaries
+</a>
+may
+also
+augment
+existing
+<a href="#dfn-thing" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-thing-51">
+Things
+</a>
+with
+additional
+capabilities
+or
+compose
+a
+new
+<a href="#dfn-thing" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-52">
+Thing
+</a>
+out
+of
+multiple
+available
+<a href= "#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-53">
+Things
+</a>,
+thereby
+forming
+a
+<a href= "#dfn-virtual-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-virtual-thing-6">
+Virtual
+Thing
+</a>.
+To
+<a href= "#dfn-consumer" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-17">
+Consumers
+</a>,
+<a href= "#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-9">
+Intermediaries
+</a>
+are
+just
+another
+kind
+of
+<a href="#dfn-thing" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-thing-54">
+Thing
+</a>,
+as
+they
+possess
+<a href= "#dfn-wot-thing-description" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-wot-thing-description-8">
+WoT
+Thing
+Descriptions
+</a>
+and
+provide
+a
+<a href="#dfn-wot-interface" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-interface-3">
+WoT
+Interface
+</a>.
+They
+may
+be
+indistinguishable
+from
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-55">
+Things
+</a>
+that
+are
+directly
+representing
+physical
+devices
+in
+a
+layered
+system
+architecture
+like
+the
+Web
+[
+<cite>
+<a class="bibref" data-link-type= "biblio" href="#bib-rest" title= "REST: Architectural Styles and the Design of Network-based Software Architectures">
+REST
+</a>
+</cite>
+].
+</p>
+<figure id="intermediary">
+<img src= "images/architecture/intermediary.png" srcset= "images/architecture/intermediary.svg" class="wot-arch-diagram" alt="intermediary" />
+<figcaption>
+<a class="self-link" href="#intermediary">
+Figure
+<bdi class="figno">
+18
+</bdi>
+</a>
+<span class= "fig-title">
+Intermediary
+</span>
+</figcaption>
+</figure>
+<p>
+Another
+remedy
+for
+restricted
+local
+networks
+is
+binding
+the
+<a href="#dfn-wot-interface" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-wot-interface-4">
+WoT
+Interface
+</a>
+to
+a
+protocol
+that
+establishes
+the
+connection
+from
+the
+<a href= "#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-56">
+Thing
+</a>
+within
+the
+local
+network
+to
+a
+publicly
+reachable
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-consumer-18">
+Consumer
+</a>.
+</p>
+<p>
+The
+concepts
+of
+<abbr title= "World Wide Web Consortium">
+W3C
+</abbr>
+WoT
+are
+applicable
+to
+all
+levels
+relevant
+for
+IoT
+applications:
+the
+device
+level,
+edge
+level,
+and
+cloud
+level.
+This
+fosters
+common
+interfaces
+and
+APIs
+across
+the
+different
+levels
+and
+enables
+various
+integration
+patterns
+such
+as
+Thing-to-Thing,
+Thing-to-Gateway,
+Thing-to-Cloud,
+Gateway-to-Cloud,
+and
+even
+cloud
+federation,
+i.e.,
+interconnecting
+cloud
+computing
+environments
+of
+two
+or
+more
+service
+providers,
+for
+IoT
+applications.
+<a href="#architecture-abstract" class="fig-ref" title="Abstract Architecture of W3C WoT">
+Figure
+<bdi class= "">
+19
+</bdi>
+</a>
+gives
+an
+overview
+how
+the
+WoT
+concepts
+introduced
+above
+can
+be
+applied
+and
+combined
+to
+address
+the
+use
+cases
+described
+in
+the
+<em>
+WoT
+Use
+Cases
+and
+Requirements
+</em>
+document
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-wot-use-cases-requirements" title= "Web of Things (WoT) Use Cases and Requirements">
+WOT-USE-CASES-REQUIREMENTS
+</a>
+</cite>
+].
+</p>
+<figure id="architecture-abstract">
+<img src= "images/architecture/overview.png" srcset= "images/architecture/overview.svg" class="wot-arch-diagram" alt= "architecture overview" />
+<figcaption>
+<a class="self-link" href= "#architecture-abstract">
+Figure
+<bdi class="figno">
+19
+</bdi>
+</a>
+<span class="fig-title">
+Abstract
+Architecture
+of
+<abbr title= "World Wide Web Consortium">
+W3C
+</abbr>
+WoT
+</span>
+</figcaption>
+</figure>
+</section>
+<section id="sec-affordances">
+<div class="header-wrapper">
+<h3 id="x6-2-affordances">
+<bdi class="secno">
+6.2
+</bdi>
+Affordances
+</h3>
+<a class="self-link" href="#sec-affordances" aria-label= "Permalink for Section 6.2">
+</a>
+</div>
+<p>
+A
+central
+aspect
+in
+<abbr title= "World Wide Web Consortium">
+W3C
+</abbr>
+WoT
+is
+the
+provision
+of
+machine-readable
+metadata
+(i.e.,
+<a href= "#dfn-wot-thing-description" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-wot-thing-description-9">
+WoT
+Thing
+Descriptions
+</a>
+).
+Ideally,
+such
+metadata
+is
+self-descriptive,
+so
+that
+<a href="#dfn-consumer" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-consumer-19">
+Consumers
+</a>
+are
+able
+to
+identify
+<em>
+what
+</em>
+capabilities
+a
+<a href="#dfn-thing" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-57">
+Thing
+</a>
+provides
+and
+<em>
+how
+</em>
+to
+use
+the
+provided
+capabilities.
+A
+key
+to
+this
+self-descriptiveness
+lies
+in
+the
+concept
+of
+<em>
+affordances
+</em>.
+</p>
+<p>
+The
+term
+affordance
+originates
+in
+ecological
+psychology,
+but
+was
+adopted
+in
+the
+field
+of
+Human-Computer
+Interaction
+[
+<cite>
+<a class= "bibref" data-link-type="biblio" href="#bib-hci" title= "The Encyclopedia of Human-Computer Interaction, 2nd Ed">
+HCI
+</a>
+</cite>
+]
+based
+on
+the
+definition
+by
+Donald
+Norman:
+"'Affordance'
+refers
+to
+the
+perceived
+and
+actual
+properties
+of
+the
+thing,
+primarily
+those
+fundamental
+properties
+that
+determine
+just
+how
+the
+thing
+could
+possibly
+be
+used."
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href="#bib-norman" title= "The Psychology of Everyday Things">
+NORMAN
+</a>
+</cite>
+]
+</p>
+<p>
+An
+example
+for
+this
+is
+a
+door
+with
+a
+handle.
+The
+door
+handle
+is
+an
+affordance,
+which
+suggests
+that
+the
+door
+can
+be
+opened.
+For
+humans,
+a
+door
+handle
+usually
+also
+suggests
+<em>
+how
+</em>
+the
+door
+can
+be
+opened;
+an
+American
+knob
+suggests
+twisting,
+a
+European
+lever
+handle
+suggests
+pressing
+down.
+</p>
+<p>
+The
+hypermedia
+principle,
+which
+is
+one
+of
+the
+core
+foundations
+of
+the
+REST
+architectural
+style
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href="#bib-rest" title= "REST: Architectural Styles and the Design of Network-based Software Architectures">
+REST
+</a>
+</cite>
+],
+demands
+that
+any
+piece
+of
+information
+available
+on
+the
+Web
+be
+linked
+to
+other
+pieces
+of
+information
+so
+that
+the
+consumer
+of
+the
+information
+gets
+explicit
+knowledge
+about
+how
+to
+navigate
+the
+Web
+and
+control
+Web
+applications.
+Here,
+the
+simultaneous
+presentation
+of
+information
+and
+control
+(provided
+in
+the
+form
+of
+hyperlinks)
+is
+a
+mechanism
+that
+<em>
+affords
+</em>
+Web
+clients
+the
+means
+to
+drive
+Web
+applications.
+In
+this
+context,
+an
+affordance
+is
+the
+description
+of
+a
+hyperlink
+(e.g.,
+via
+a
+link
+relation
+type
+and
+link
+target
+attributes)
+suggesting
+Web
+clients
+how
+to
+navigate
+and
+possibly
+how
+to
+act
+on
+the
+linked
+resource.
+Hence,
+links
+provide
+navigation
+affordances.
+</p>
+<p>
+Drawn
+from
+this
+hypermedia
+principle,
+the
+Web
+of
+Things
+defines
+<a href="#dfn-interaction-affordance" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-interaction-affordance-2">
+Interaction
+Affordances
+</a>
+as
+metadata
+of
+a
+Thing
+that
+shows
+and
+describes
+the
+possible
+choices
+to
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-consumer-20">
+Consumers
+</a>,
+thereby
+suggesting
+how
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-consumer-21">
+Consumers
+</a>
+may
+interact
+with
+the
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-58">
+Thing
+</a>.
+A
+general
+<a href="#dfn-interaction-affordance" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-interaction-affordance-3">
+Interaction
+Affordance
+</a>
+is
+navigation,
+which
+is
+activated
+by
+following
+a
+link,
+thereby
+enabling
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-consumer-22">
+Consumers
+</a>
+to
+browse
+the
+Web
+of
+Things.
+<a href="#sec-interaction-model" class= "sec-ref">
+<bdi class="secno">
+6.5
+</bdi>
+Interaction
+Model
+</a>
+defines
+three
+more
+types
+of
+Interaction
+Affordances
+for
+<abbr title="World Wide Web Consortium">
+W3C
+</abbr>
+WoT:
+<a href= "#dfn-property" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-property-3">
+Properties
+</a>,
+<a href="#dfn-action" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-action-3">
+Actions
+</a>,
+and
+<a href="#dfn-event" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-event-3">
+Events
+</a>.
+</p>
+<p>
+Overall,
+this
+<abbr title="World Wide Web Consortium">
+W3C
+</abbr>
+WoT
+definition
+is
+aligned
+with
+HCI
+and
+interaction
+designers,
+who
+create
+physical
+Things,
+as
+well
+as
+the
+REST
+and
+microservice
+community,
+who
+is
+working
+on
+Web
+services
+in
+general.
+</p>
+</section>
+<section id="sec-web-thing">
+<div class="header-wrapper">
+<h3 id="x6-3-web-thing">
+<bdi class="secno">
+6.3
+</bdi>
+Web
+Thing
+</h3>
+<a class="self-link" href="#sec-web-thing" aria-label= "Permalink for Section 6.3">
+</a>
+</div>
+<p>
+A
+<a href="#dfn-web-thing" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-web-thing-2">
+Web
+Thing
+</a>
+has
+four
+architectural
+aspects
+of
+interest:
+its
+<em>
+behavior
+</em>,
+its
+<em>
+<a href="#dfn-interaction-affordance" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-interaction-affordance-4">
+Interaction
+Affordances
+</a>
+</em>,
+its
+<em>
+<a href="#dfn-security-configuration" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-security-configuration-3">
+security
+configuration
+</a>
+</em>,
+and
+its
+<em>
+<a href= "#dfn-wot-protocol-binding" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-wot-protocol-binding-1">
+Protocol
+Bindings
+</a>
+</em>,
+as
+depicted
+in
+<a href="#arch-webthing" class= "fig-ref" title="Architectural Aspects of a Thing">
+Figure
+<bdi class="">
+20
+</bdi>
+</a>.
+The
+behavior
+aspect
+of
+a
+<a href= "#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-59">
+Thing
+</a>
+includes
+both
+the
+autonomous
+behavior
+and
+the
+handlers
+for
+the
+<a href= "#dfn-interaction-affordance" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-interaction-affordance-5">
+Interaction
+Affordances
+</a>.
+The
+<a href="#dfn-interaction-affordance" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-interaction-affordance-6">
+Interaction
+Affordances
+</a>
+provide
+a
+model
+of
+how
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-consumer-23">
+Consumers
+</a>
+can
+interact
+with
+the
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-60">
+Thing
+</a>
+through
+abstract
+operations,
+but
+without
+reference
+to
+a
+specific
+network
+protocol
+or
+data
+encoding.
+The
+<a href="#dfn-wot-protocol-binding" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-protocol-binding-2">
+protocol
+binding
+</a>
+adds
+the
+additional
+detail
+needed
+to
+map
+each
+<a href= "#dfn-interaction-affordance" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-interaction-affordance-7">
+Interaction
+Affordance
+</a>
+to
+concrete
+messages
+of
+a
+certain
+protocol.
+In
+general,
+different
+concrete
+protocols
+may
+be
+used
+to
+support
+different
+subsets
+of
+<a href="#dfn-interaction-affordance" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-interaction-affordance-8">
+Interaction
+Affordances
+</a>,
+even
+within
+a
+single
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-61">
+Thing
+</a>.
+The
+<a href="#dfn-security-configuration" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-security-configuration-4">
+security
+configuration
+</a>
+aspect
+of
+a
+Thing
+represents
+the
+mechanisms
+used
+to
+control
+access
+to
+the
+<a href="#dfn-interaction-affordance" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-interaction-affordance-9">
+Interaction
+Affordances
+</a>
+and
+the
+management
+of
+related
+<a href= "#dfn-public-security-metadata" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-public-security-metadata-1">
+Public
+Security
+Metadata
+</a>
+and
+<a href="#dfn-private-security-data" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-private-security-data-1">
+Private
+Security
+Data
+</a>.
+</p>
+<figure id="arch-webthing">
+<img src= "images/architecture/webthing.png" srcset= "images/architecture/webthing.svg" class="wot-arch-diagram" alt= "web thing" />
+<figcaption>
+<a class="self-link" href="#arch-webthing">
+Figure
+<bdi class="figno">
+20
+</bdi>
+</a>
+<span class= "fig-title">
+Architectural
+Aspects
+of
+a
+Thing
+</span>
+</figcaption>
+</figure>
+</section>
+<section id="lifecycle">
+<div class="header-wrapper">
+<h3 id="x6-4-lifecycle">
+<bdi class="secno">
+6.4
+</bdi>
+Lifecycle
+</h3>
+<a class="self-link" href="#lifecycle" aria-label= "Permalink for Section 6.4">
+</a>
+</div>
+<p>
+In
+a
+deployment,
+that
+applies
+the
+WoT
+architecture
+principles,
+different
+entities
+interact
+with
+each
+other
+and
+exchange
+information
+between
+them.
+Elements
+of
+a
+WoT
+deployment
+are
+<a href= "#dfn-device" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-device-3">
+devices
+</a>,
+<a href="#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-10">
+intermediaries
+</a>,
+<a href= "#dfn-consumer" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-24">
+consumers
+</a>
+and
+<em>
+directories
+</em>.
+Each
+element
+has
+its
+own
+(intrinsic)
+<a href="#dfn-thing" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-62">
+Thing
+</a>
+lifecycle.
+These
+elements
+build
+a
+system,
+where
+the
+entire
+system
+has
+a
+<em>
+System
+lifecycle
+</em>,
+i.e.
+the
+system
+has
+several
+states
+and
+transitions
+through
+some
+states
+to
+become
+operational.
+This
+implies
+that
+devices
+go
+through
+their
+lifecycle
+to
+become
+operational,
+and
+devices
+must
+be
+known
+to
+others
+before
+they
+can
+be
+used.
+</p>
+<p>
+The
+following
+sections
+describe
+the
+<em>
+System
+lifecycle
+</em>
+and
+the
+<em>
+Thing
+lifecycle
+</em>.
+They
+contain
+sample
+flows
+to
+illustrate
+the
+different
+states
+and
+phases
+of
+Things
+in
+a
+deployment.
+One
+of
+the
+purposes
+of
+this
+section
+is
+to
+clarify
+terminology
+and
+ensure
+that
+a
+the
+concepts
+of
+a
+common
+lifecycle
+model
+are
+considered
+by
+implementers
+of
+Web
+Things.
+</p>
+<p>
+The
+actor
+in
+the
+left
+hand
+side
+of
+these
+diagrams
+can
+be
+understood
+as
+the
+device
+owner
+or
+manufacturer.
+The
+actor
+on
+the
+right
+is
+the
+end
+user,
+who
+uses
+the
+device
+in
+an
+application.
+</p>
+<section id="simple-system-lifecycle">
+<div class="header-wrapper">
+<h4 id="x6-4-1-simple-system-lifecycle">
+<bdi class= "secno">
+6.4.1
+</bdi>
+Simple
+System
+Lifecycle
+</h4>
+<a class="self-link" href="#simple-system-lifecycle" aria-label= "Permalink for Section 6.4.1">
+</a>
+</div>
+<p>
+The
+following
+sequence
+diagram
+shows
+an
+example
+of
+the
+flow
+of
+system
+that
+consists
+of
+two
+directly
+communicating
+devices.
+</p>
+<p>
+Before
+a
+device
+can
+be
+used
+in
+this
+scenario,
+it
+has
+to
+be
+bootstrapped
+and
+onboarded
+to
+the
+consumer.
+In
+the
+onboarding
+operation
+the
+consumer
+and
+the
+device
+get
+to
+know
+each
+other
+-
+this
+may
+either
+be
+performed
+by
+a
+discovery
+process,
+or
+via
+a
+registration
+operation,
+where
+the
+consumer
+is
+registered
+with
+the
+device
+or
+vice-versa.
+</p>
+<p>
+After
+an
+activation
+step
+(which
+may
+consist
+of
+several
+operations,
+such
+as
+provisioning,
+configuration
+etc.)
+the
+<a href= "#dfn-device" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-device-4">
+device
+</a>
+and
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-25">
+consumer
+</a>
+are
+in
+regular
+operation
+mode.
+When
+the
+device
+is
+no
+longer
+required
+in
+this
+scenario,
+it
+will
+be
+offboarded
+from
+the
+consumer.
+After
+this
+operation
+it
+can
+be
+decommissioned
+and
+destroyed.
+</p>
+<figure id="fig-simple-system-lifecycle">
+<img src= "images/message-flows/lifecycle-1.svg" srcset= "images/message-flows/lifecycle-1.svg" class="wot-arch-diagram" alt="Simple System Lifecycle" />
+<figcaption>
+<a class="self-link" href= "#fig-simple-system-lifecycle">
+Figure
+<bdi class= "figno">
+21
+</bdi>
+</a>
+<span class="fig-title">
+Simple
+System
+Lifecycle
+</span>
+</figcaption>
+</figure>
+</section>
+<section id="system-lifecycle-no-directory">
+<div class="header-wrapper">
+<h4 id="x6-4-2-system-lifecycle-with-registration">
+<bdi class= "secno">
+6.4.2
+</bdi>
+System
+Lifecycle
+with
+Registration
+</h4>
+<a class="self-link" href="#system-lifecycle-no-directory" aria-label="Permalink for Section 6.4.2">
+</a>
+</div>
+<p>
+The
+following
+sequence
+diagram
+shows
+an
+example
+of
+the
+flow
+of
+system
+that
+contains
+three
+entities:
+a
+device,
+a
+consumer
+and
+a
+directory.
+</p>
+<p>
+This
+flow
+is
+very
+similar
+to
+the
+flow
+in
+the
+previous
+section,
+in
+addition
+it
+contains
+a
+<em>
+directory
+</em>
+entity,
+which
+maintains
+a
+catalog
+of
+devices.
+In
+WoT
+this
+catalog
+is
+a
+set
+of
+<a href="#dfn-thing-description" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-description-17">
+thing
+descriptions
+</a>
+After
+a
+device
+is
+bootstrapped
+like
+in
+the
+previous
+scenario,
+it
+is
+registered
+with
+the
+directory.
+</p>
+<p>
+The
+directory
+acts
+as
+an
+information
+broker
+between
+the
+actor
+on
+the
+left
+and
+the
+actor
+on
+the
+consumer
+side.
+This
+decouples
+the
+device
+owner
+from
+the
+consumer,
+where
+the
+discovery
+acts
+as
+a
+middle
+man
+to
+enable
+discovery
+for
+consumers.
+</p>
+<figure id="lifecycle-2">
+<img src= "images/message-flows/lifecycle-2.svg" srcset= "images/message-flows/lifecycle-2.svg" class="wot-arch-diagram" alt="Simple System Lifecycle" />
+<figcaption>
+<a class="self-link" href="#lifecycle-2">
+Figure
+<bdi class="figno">
+22
+</bdi>
+</a>
+<span class="fig-title">
+System
+lifecycle
+with
+registration
+</span>
+</figcaption>
+</figure>
+</section>
+<section id="thing-lifecycle">
+<div class="header-wrapper">
+<h4 id="x6-4-3-thing-lifecycle">
+<bdi class="secno">
+6.4.3
+</bdi>
+Thing
+Lifecycle
+</h4>
+<a class="self-link" href="#thing-lifecycle" aria-label= "Permalink for Section 6.4.3">
+</a>
+</div>
+<p>
+Bootstrapping
+and
+provisioning
+of
+devices
+is
+an
+essential
+part
+of
+setting
+up
+devices
+in
+all
+IoT
+protocol
+suites.
+</p>
+<p>
+The
+main
+scenarios
+for
+provisioning
+devices
+with
+WoT
+are
+as
+follows:
+</p>
+<ul>
+<li>
+A
+device
+is
+already
+provisioned
+and
+operational
+in
+a
+given
+deployment.
+Make
+it
+work
+with
+WoT.
+</li>
+<li>
+A
+device
+is
+already
+provisioned
+and
+operational
+in
+a
+given
+deployment.
+For
+management
+purposes,
+<em>
+describe
+</em>
+the
+device
+lifecycle
+stages
+in
+a
+<a href="#dfn-thing-description" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-description-18">
+Thing
+Description
+</a>.
+</li>
+<li>
+Bootstrap
+and
+provision
+a
+device
+directly
+with
+WoT,
+in
+order
+to
+become
+operational
+for
+WoT.
+</li>
+</ul>
+<p>
+Various
+provisioning
+schemes
+are
+being
+used
+in
+IoT
+protocol
+suites.
+The
+text
+in
+this
+section
+is
+based
+on
+<a href= "https://github.com/w3c/wot-architecture/tree/master/proposals">
+proposals
+</a>
+and
+studies,
+<a href= "https://w3c.github.io/wot-architecture/proposals/lifecycle/Device-lifecycle-comparisons.pdf">
+comparing
+various
+provisioning
+schemes
+</a>,
+such
+as
+OCF,
+OneM2M,
+Lightweight
+OneM2M,
+Thing
+to
+Thing
+Research
+Group
+(T2TRG),
+OPC-UA/Anima,
+etc.
+</p>
+<div class="note" role="note" id="issue-container-generatedID-0">
+<div role="heading" class="note-title marker" id="h-note-0" aria-level="5">
+<span>
+Note
+</span>
+</div>
+<p class="">
+The
+provisioning
+model
+presented
+in
+this
+section
+resembles
+the
+T2TRG
+provisioning
+model.
+</p>
+</div>
+<p>
+Common
+elements
+of
+device
+bootstrapping
+and
+provisioning
+across
+various
+IoT
+protocol
+suites
+are
+as
+follows:
+</p>
+<ul>
+<li>
+Establish
+the
+chain
+of
+trust,
+e.g.
+secure
+storage,
+keys,
+certificates.
+This
+may
+involve
+various
+solutions,
+such
+as
+manufacturer
+certificates,
+out-of-band
+key
+provisioning,
+connecting
+to
+a
+provisioning
+server,
+etc.
+</li>
+<li>
+Establish
+device
+ownership,
+using
+a
+provisioning
+tool
+or
+service.
+For
+instance,
+the
+device
+can
+be
+owned
+by
+a
+network
+entity,
+or
+network
+service,
+or
+service
+provider,
+or
+the
+end
+user.
+</li>
+<li>
+Provision
+the
+device
+with
+the
+access
+control
+lists
+for
+the
+tenants
+or
+various
+levels
+of
+users.
+</li>
+<li>
+Provision
+the
+device
+with
+access
+to
+the
+services
+it
+uses.
+</li>
+<li>
+Configure
+the
+device
+with
+used
+and
+the
+exposed
+services.
+</li>
+<li>
+Provision
+and
+configure
+the
+WoT
+runtime
+in
+the
+device.
+</li>
+<li>
+Update
+the
+configurations
+or
+provisioning
+data.
+</li>
+<li>
+Decommission
+a
+user,
+application,
+service,
+or
+provisioning.
+</li>
+<li>
+Return
+the
+device
+to
+the
+initial
+state
+before
+provisioning
+(e.g.
+factory
+reset).
+</li>
+<li>
+Decommission
+and
+irreversibly
+destroy
+a
+device.
+</li>
+</ul>
+<p>
+Taken
+into
+account
+these
+provisioning
+flows,
+in
+general
+a
+device
+can
+be
+in
+one
+of
+the
+following
+states:
+</p>
+<ul>
+<li>
+<strong>
+Manufactured
+</strong>:
+the
+device
+is
+flashed
+with
+a
+software
+image.
+In
+the
+case
+it
+is
+certified
+for
+a
+certain
+protocol
+suite,
+it
+may
+be
+permitted
+or
+capable
+of
+doing
+only
+limited
+operations,
+such
+as
+a
+certain
+bootstrapping
+procedure.
+</li>
+<li>
+<strong>
+Bootstrapped
+</strong>:
+the
+device
+has
+an
+identity
+and
+ownership
+established,
+being
+ready
+for
+the
+next
+provisioning
+steps,
+like
+configuration,
+service
+provisioning
+etc.
+This
+state
+has
+different
+names
+in
+various
+protocol
+suites,
+for
+instance
+it
+is
+called
+<em>
+onboarded
+</em>
+in
+OCF,
+<em>
+bootstrapped
+</em>
+in
+T2TRG,
+OPC-UA,
+Anima,
+LwM2M,
+<em>
+initial
+provisioning
+</em>
+in
+OneM2M,
+etc.
+</li>
+<li>
+<strong>
+Operational
+</strong>:
+the
+device
+is
+provisioned
+and
+configured,
+working
+in
+normal
+mode.
+Some
+configuration
+is
+possible
+without
+leaving
+this
+state.
+That
+may
+include
+installing
+and
+uninstalling
+applications,
+reconfiguring
+settings,
+etc.
+Note
+that
+a
+device
+can
+be
+operational
+in
+its
+own
+native
+protocol
+suite
+and
+managed
+by
+a
+WoT
+gateway,
+or
+can
+be
+operational
+for
+WoT
+(which
+may
+be
+an
+application
+on
+the
+device),
+or
+may
+be
+operational
+for
+Wot
+and
+directly
+provisioned
+for
+WoT.
+</li>
+<li>
+<strong>
+Maintenance
+</strong>:
+the
+device
+operational
+state
+is
+interrupted
+for
+updating
+its
+software
+and/or
+configuration.
+</li>
+<li>
+<strong>
+Destroyed
+</strong>:
+the
+device
+has
+been
+wiped
+out
+of
+all
+data
+and
+software.
+Hardware
+kill
+features
+may
+be
+activated.
+The
+device
+may
+be
+physically
+destroyed
+and
+never
+used
+again.
+This
+state
+is
+relevant
+for
+device
+management
+purposes.
+It
+does
+not
+exist
+in
+OneM2M,
+LwM2M,
+OCF,
+T2TRG
+and
+is
+called
+<em>
+End-of-life
+</em>
+in
+OPC-UA
+and
+Anima.
+</li>
+</ul>
+<figure id="fig-device-lifecycle">
+<img src= "images/architecture/device-lifecycle-1.svg" srcset= "images/architecture/device-lifecycle-1.svg" class= "wot-arch-diagram" alt="Device Lifecycle" />
+<figcaption>
+<a class="self-link" href= "#fig-device-lifecycle">
+Figure
+<bdi class="figno">
+23
+</bdi>
+</a>
+<span class="fig-title">
+Device
+Lifecycle
+</span>
+</figcaption>
+</figure>
+<p>
+The
+typical
+transitions
+between
+lifecycle
+states
+are
+the
+following:
+</p>
+<ul>
+<li>
+<strong>
+Bootstrapping
+</strong>
+(or
+onboarding):
+the
+device
+is
+provisioned
+with
+an
+identity,
+the
+chain
+of
+trust
+is
+established,
+e.g.
+secure
+storage,
+keys,
+certificates.
+This
+may
+involve
+various
+solutions,
+such
+as
+manufacturer
+certificates,
+out-of-band
+key
+provisioning,
+connecting
+to
+a
+provisioning
+server
+(a
+quite
+common
+scenario).
+When
+provisioning
+directly
+to
+WoT,
+the
+device
+may
+be
+registered
+with
+a
+<a href="#dfn-wot-thing-description-directory" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-thing-description-directory-6">
+Thing
+Description
+Directory
+</a>
+in
+this
+stage.
+During
+or
+after
+this
+process,
+in
+some
+protocol
+suites
+rebooting
+in
+a
+different
+mode
+of
+operation
+might
+be
+also
+needed.
+</li>
+<li>
+<strong>
+Provisioning,
+configuration,
+commissioning
+</strong>:
+the
+device
+is
+provisioned
+with
+all
+resources
+needed
+for
+its
+operation
+(services,
+applications,
+access
+control,
+databases
+etc),
+and
+these
+resources
+are
+configured
+for
+operation.
+Also,
+the
+device
+may
+be
+commissioned
+in
+a
+given
+environment.
+These
+may
+involve
+communication
+with
+a
+server,
+for
+instance
+a
+<a href= "#dfn-wot-thing-description-directory" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-thing-description-directory-7">
+Thing
+Description
+Directory
+</a>
+or
+<a href="#dfn-wot-discovery" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-discovery-3">
+Discovery
+</a>
+services.
+</li>
+<li>
+<strong>
+Settings
+</strong>:
+the
+device
+remains
+in
+<em>
+Operational
+</em>
+state,
+but
+may
+update
+system,
+service
+or
+application
+settings.
+In
+some
+cases,
+this
+may
+include
+installing
+and
+removing
+applications.
+</li>
+<li>
+<strong>
+Update
+</strong>:
+the
+device
+stops
+normal
+operation
+for
+undergoing
+updates
+in
+the
+<em>
+Maintenance
+</em>
+state,
+similar
+to
+the
+ones
+during
+provisioning.
+This
+may
+include
+installing
+new
+software,
+or
+removing,
+installing
+or
+updating
+resources
+and
+their
+configuration.
+It
+may
+also
+include
+re-commissioning.
+Returning
+to
+<em>
+Operational
+</em>
+state
+may
+be
+achieved
+by
+resuming
+operation
+with
+updated
+resources,
+or
+may
+require
+a
+restart
+of
+services,
+or
+rebooting
+the
+device.
+</li>
+<li>
+<strong>
+Re-bootstrapping
+</strong>:
+the
+device
+identity,
+owner
+and
+related
+resources
+may
+be
+changed
+as
+described
+in
+the
+<em>
+Bootstrapping
+</em>
+process.
+</li>
+<li>
+<strong>
+Factory
+Reset
+</strong>:
+the
+device
+is
+returned
+to
+its
+factory
+default
+state.
+</li>
+<li>
+<strong>
+Destroy
+</strong>:
+the
+device
+is
+erased
+from
+all
+data,
+software
+and
+may
+be
+physically
+destroyed.
+</li>
+</ul>
+</section>
+</section>
+<section id="sec-interaction-model">
+<div class="header-wrapper">
+<h3 id="x6-5-interaction-model">
+<bdi class="secno">
+6.5
+</bdi>
+Interaction
+Model
+</h3>
+<a class="self-link" href="#sec-interaction-model" aria-label= "Permalink for Section 6.5">
+</a>
+</div>
+<p>
+Originally,
+a
+Web
+resource
+usually
+represented
+a
+document
+on
+the
+World
+Wide
+Web
+that
+can
+simply
+be
+fetched
+by
+a
+Web
+client.
+With
+the
+introduction
+of
+Web
+services,
+resources
+became
+more
+generic
+interaction
+entities
+that
+can
+implement
+any
+kind
+of
+behavior.
+This
+very
+high
+level
+of
+abstraction
+makes
+it
+hard
+to
+provide
+a
+loose
+coupling
+between
+applications
+and
+resources
+due
+to
+the
+manifold
+interaction
+possibilities.
+As
+a
+result,
+at
+the
+time
+of
+writing,
+typical
+API
+descriptions
+consist
+of
+a
+static
+mapping
+from
+an
+application
+intent
+to
+a
+resource
+address,
+method,
+request
+payload
+structure,
+response
+payload
+structure,
+and
+expected
+errors.
+This
+imposes
+a
+tight
+coupling
+between
+Web
+client
+and
+Web
+service.
+</p>
+<p>
+The
+<a href="#dfn-interaction-model" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-interaction-model-1">
+Interaction
+Model
+</a>
+of
+<abbr title="World Wide Web Consortium">
+W3C
+</abbr>
+WoT
+introduces
+an
+intermediate
+abstraction
+that
+formalizes
+the
+mapping
+from
+application
+intent
+to
+concrete
+protocol
+operations
+and
+also
+narrows
+the
+possibilities
+how
+<a href="#dfn-interaction-affordance" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-interaction-affordance-10">
+Interaction
+Affordances
+</a>
+can
+be
+modeled.
+</p>
+<p>
+<span class="rfc2119-assertion" id="arch-affordances">
+In
+addition
+to
+navigation
+affordances
+(i.e.,
+Web
+links),
+<a href= "#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-63">
+Things
+</a>
+<em class="rfc2119">
+MAY
+</em>
+offer
+three
+other
+types
+of
+<a href="#dfn-interaction-affordance" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-interaction-affordance-11">
+Interaction
+Affordances
+</a>
+defined
+by
+this
+specification:
+<a href="#dfn-property" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-property-4">
+Properties
+</a>,
+<a href="#dfn-action" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-action-4">
+Actions
+</a>,
+and
+<a href="#dfn-event" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-event-4">
+Events
+</a>.
+</span>
+While
+this
+narrow
+waist
+allows
+to
+decouple
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-consumer-26">
+Consumers
+</a>
+and
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-64">
+Things
+</a>,
+these
+four
+types
+of
+<a href= "#dfn-interaction-affordance" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-interaction-affordance-12">
+Interaction
+Affordances
+</a>
+are
+still
+able
+to
+model
+virtually
+all
+interaction
+kinds
+found
+in
+IoT
+devices
+and
+services.
+</p>
+<section id="properties">
+<div class="header-wrapper">
+<h4 id="x6-5-1-properties">
+<bdi class="secno">
+6.5.1
+</bdi>
+Properties
+</h4>
+<a class="self-link" href="#properties" aria-label= "Permalink for Section 6.5.1">
+</a>
+</div>
+<p>
+A
+<a href="#dfn-property" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-property-5">
+Property
+</a>
+is
+an
+<a href= "#dfn-interaction-affordance" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-interaction-affordance-13">
+Interaction
+Affordance
+</a>
+that
+exposes
+the
+state
+of
+the
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-65">
+Thing
+</a>.
+The
+state
+exposed
+by
+a
+<a href= "#dfn-property" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-property-6">
+Property
+</a>
+can
+be
+retrievable
+(readable).
+Optionally,
+the
+state
+exposed
+by
+a
+Property
+may
+be
+updated
+(writable).
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-66">
+Things
+</a>
+may
+choose
+to
+make
+Properties
+observable
+by
+pushing
+the
+new
+state
+after
+a
+change
+(cf.
+Observing
+Resources
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href="#bib-rfc7641" title= "Observing Resources in the Constrained Application Protocol (CoAP)">
+RFC7641
+</a>
+</cite>
+]).
+In
+the
+case
+of
+a
+read-only
+state,
+an
+Action
+can
+be
+used
+to
+update
+the
+state.
+</p>
+<p>
+<span class="rfc2119-assertion" id="arch-property-dataschema">
+If
+the
+data
+format
+is
+not
+fully
+specified
+by
+the
+Protocol
+Binding
+used
+(e.g.,
+through
+a
+media
+type),
+Properties
+<em class= "rfc2119">
+MAY
+</em>
+contain
+one
+<a href="#dfn-data-schema" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-data-schema-1">
+data
+schema
+</a>
+for
+the
+exposed
+state.
+</span>
+</p>
+<p>
+Examples
+of
+Properties
+are
+sensor
+values
+(read-only),
+stateful
+actuators
+(read-write),
+configuration
+parameters
+(read-write),
+Thing
+status
+(read-only
+or
+read-write),
+or
+computation
+results
+(read-only).
+</p>
+</section>
+<section id="actions">
+<div class="header-wrapper">
+<h4 id="x6-5-2-actions">
+<bdi class="secno">
+6.5.2
+</bdi>
+Actions
+</h4>
+<a class="self-link" href="#actions" aria-label= "Permalink for Section 6.5.2">
+</a>
+</div>
+<p>
+An
+<a href="#dfn-action" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-action-5">
+Action
+</a>
+is
+an
+<a href= "#dfn-interaction-affordance" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-interaction-affordance-14">
+Interaction
+Affordance
+</a>
+that
+allows
+to
+invoke
+a
+function
+of
+the
+<a href= "#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-67">
+Thing
+</a>.
+<span class="rfc2119-assertion" id="arch-action-functions">
+An
+Action
+<em class="rfc2119">
+MAY
+</em>
+manipulate
+state
+that
+is
+not
+directly
+exposed
+(cf.
+Properties),
+manipulate
+multiple
+Properties
+at
+a
+time,
+or
+manipulate
+Properties
+based
+on
+internal
+logic
+(e.g.,
+toggle).
+</span>
+<span class= "rfc2119-assertion" id="arch-action-process">
+Invoking
+an
+Action
+<em class="rfc2119">
+MAY
+</em>
+also
+trigger
+a
+process
+on
+the
+Thing
+that
+manipulates
+state
+(including
+physical
+state
+through
+actuators)
+over
+time.
+</span>
+</p>
+<p>
+<span class="rfc2119-assertion" id="arch-action-dataschema">
+If
+the
+data
+format
+is
+not
+fully
+specified
+by
+the
+Protocol
+Binding
+used
+(e.g.,
+through
+a
+media
+type),
+Actions
+<em class="rfc2119">
+MAY
+</em>
+contain
+<a href="#dfn-data-schema" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-data-schema-2">
+data
+schemas
+</a>
+for
+input
+parameters
+and
+output
+results.
+</span>
+</p>
+<p>
+Some
+examples
+for
+Actions
+are
+setting
+multiple
+Properties
+simultaneously,
+changing
+Properties
+over
+time
+such
+as
+fading
+the
+brightness
+of
+a
+light
+(dimming)
+or
+with
+a
+process
+that
+shall
+not
+be
+disclosed
+such
+as
+a
+proprietary
+control
+loop
+algorithm,
+or
+invoking
+a
+long-lasting
+process
+such
+as
+printing
+a
+document.
+</p>
+</section>
+<section id="events">
+<div class="header-wrapper">
+<h4 id="x6-5-3-events">
+<bdi class="secno">
+6.5.3
+</bdi>
+Events
+</h4>
+<a class="self-link" href="#events" aria-label= "Permalink for Section 6.5.3">
+</a>
+</div>
+<p>
+An
+<a href="#dfn-event" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-event-5">
+Event
+</a>
+is
+an
+<a href= "#dfn-interaction-affordance" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-interaction-affordance-15">
+Interaction
+Affordance
+</a>,
+which
+describes
+an
+event
+source
+that
+pushes
+data
+asynchronously
+from
+the
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-68">
+Thing
+</a>
+to
+the
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-consumer-27">
+Consumer
+</a>.
+Here
+not
+state,
+but
+state
+transitions
+(i.e.,
+events)
+are
+communicated.
+<span class= "rfc2119-assertion" id="arch-event-trigger">
+Events
+<em class= "rfc2119">
+MAY
+</em>
+be
+triggered
+through
+conditions
+that
+are
+not
+exposed
+as
+Properties.
+</span>
+</p>
+<p>
+<span class="rfc2119-assertion" id="arch-event-dataschema">
+If
+the
+data
+is
+not
+fully
+specified
+by
+the
+Protocol
+Binding
+used
+(e.g.,
+through
+a
+media
+type),
+Events
+<em class="rfc2119">
+MAY
+</em>
+contain
+<a href="#dfn-data-schema" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-data-schema-3">
+data
+schemas
+</a>
+for
+the
+event
+data
+and
+subscription
+control
+messages
+(e.g.,
+a
+callback
+URI
+to
+subscribe
+with
+a
+Webhook).
+</span>
+</p>
+<p>
+Examples
+of
+<a href="#dfn-event" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-event-6">
+Events
+</a>
+are
+discrete
+events
+such
+as
+an
+alarm
+or
+samples
+of
+a
+time
+series
+that
+are
+sent
+regularly.
+</p>
+</section>
+</section>
+<section id="sec-hypermedia-controls">
+<div class="header-wrapper">
+<h3 id="x6-6-hypermedia-controls">
+<bdi class="secno">
+6.6
+</bdi>
+Hypermedia
+Controls
+</h3>
+<a class="self-link" href="#sec-hypermedia-controls" aria-label= "Permalink for Section 6.6">
+</a>
+</div>
+<p>
+On
+the
+Web,
+an
+affordance
+is
+the
+simultaneous
+presentation
+of
+information
+and
+controls,
+such
+that
+the
+information
+becomes
+the
+affordance
+through
+which
+the
+user
+obtains
+choices.
+For
+humans,
+the
+information
+is
+usually
+text
+or
+images
+describing
+or
+decorating
+a
+hyperlink.
+The
+control
+is
+a
+Web
+link,
+which
+includes
+at
+least
+the
+URI
+of
+the
+target
+resource,
+which
+can
+be
+dereferenced
+by
+the
+Web
+browser
+(i.e.,
+the
+link
+can
+be
+followed).
+But
+also
+machines
+can
+follow
+links
+in
+a
+meaningful
+way,
+when
+the
+Web
+link
+is
+further
+described
+by
+a
+relation
+type
+and
+a
+set
+of
+target
+attributes.
+A
+<a href="#dfn-hypermedia-control" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-hypermedia-control-2">
+hypermedia
+control
+</a>
+is
+the
+machine-readable
+description
+of
+<em>
+how
+</em>
+to
+activate
+an
+affordance.
+<a href="#dfn-hypermedia-control" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-hypermedia-control-3">
+Hypermedia
+controls
+</a>
+usually
+originate
+from
+a
+Web
+server
+and
+are
+discovered
+in-band
+while
+a
+Web
+client
+is
+interacting
+with
+the
+server.
+This
+way,
+Web
+servers
+can
+drive
+clients
+through
+Web
+applications
+dynamically,
+by
+taking
+their
+current
+state
+and
+other
+factors
+such
+as
+authorization
+into
+account.
+This
+is
+opposed
+to
+out-of-band
+interface
+descriptions
+that
+need
+to
+be
+preinstalled
+or
+hardcoded
+into
+clients
+(e.g.,
+RPC,
+WS-*
+Web
+services,
+HTTP
+services
+with
+fixed
+URI-method-response
+definitions).
+</p>
+<p>
+<abbr title="World Wide Web Consortium">
+W3C
+</abbr>
+WoT
+makes
+use
+of
+two
+kinds
+of
+<a href="#dfn-hypermedia-control" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-hypermedia-control-4">
+hypermedia
+controls
+</a>:
+<em>
+Web
+links
+</em>
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-rfc8288" title="Web Linking">
+RFC8288
+</a>
+</cite>
+],
+the
+well-established
+control
+to
+navigate
+the
+Web,
+and
+<em>
+Web
+forms
+</em>
+as
+a
+more
+powerful
+control
+to
+enable
+any
+kind
+of
+operation.
+Links
+are
+already
+used
+in
+other
+IoT
+standards
+and
+<a href="#dfn-iot-platform" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-iot-platform-2">
+IoT
+platforms
+</a>
+such
+as
+CoRE
+Link
+Format
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href="#bib-rfc6690" title= "Constrained RESTful Environments (CoRE) Link Format">
+RFC6690
+</a>
+</cite>
+],
+OMA
+LWM2M
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-lwm2m" title= "Lightweight Machine to Machine Technical Specification: Core">
+LWM2M
+</a>
+</cite>
+],
+and
+OCF
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-ocf" title="OCF Core Specification">
+OCF
+</a>
+</cite>
+].
+<em>
+Form
+</em>
+is
+a
+new
+concept
+that
+besides
+<abbr title= "World Wide Web Consortium">
+W3C
+</abbr>
+WoT
+is
+also
+introduced
+by
+the
+<em>
+Constrained
+RESTful
+Application
+Language
+(CoRAL)
+</em>
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href="#bib-coral" title= "The Constrained RESTful Application Language (CoRAL)">
+CoRAL
+</a>
+</cite>
+]
+defined
+by
+the
+IETF.
+</p>
+<section id="sec-hypermedia-links">
+<div class="header-wrapper">
+<h4 id="x6-6-1-links">
+<bdi class="secno">
+6.6.1
+</bdi>
+Links
+</h4>
+<a class="self-link" href="#sec-hypermedia-links" aria-label= "Permalink for Section 6.6.1">
+</a>
+</div>
+<p>
+<em>
+Links
+</em>
+enable
+<a href="#dfn-consumer" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-28">
+Consumers
+</a>
+(or
+Web
+clients
+in
+the
+broader
+sense)
+to
+change
+the
+current
+context
+(cf.
+the
+set
+of
+resource
+representations
+currently
+rendered
+in
+the
+Web
+browser)
+or
+to
+include
+additional
+resources
+into
+the
+current
+context,
+depending
+on
+the
+relation
+between
+context
+and
+link
+target.
+<a href= "#dfn-consumer" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-29">
+Consumers
+</a>
+do
+so
+by
+<em>
+dereferencing
+</em>
+the
+target
+URI,
+that
+is,
+fetching
+the
+resource
+representation
+by
+following
+a
+link.
+</p>
+<p>
+<abbr title="World Wide Web Consortium">
+W3C
+</abbr>
+WoT
+follows
+the
+definitions
+of
+Web
+Linking
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href="#bib-rfc8288" title= "Web Linking">
+RFC8288
+</a>
+</cite>
+],
+where
+a
+link
+is
+comprised
+of:
+</p>
+<ul>
+<li>
+a
+link
+context,
+</li>
+<li>
+a
+relation
+type,
+</li>
+<li>
+a
+link
+target,
+and
+</li>
+<li>
+optionally
+target
+attributes.
+</li>
+</ul>
+<p>
+Link
+relation
+types
+are
+either
+a
+set
+of
+predefined
+tokens
+that
+are
+registered
+with
+IANA
+[
+<cite>
+<a class="bibref" data-link-type= "biblio" href="#bib-iana-relations" title= "Link Relations">
+IANA-RELATIONS
+</a>
+</cite>
+],
+(e.g.
+<code>
+stylesheet
+</code>
+),
+or
+extension
+types
+in
+the
+form
+of
+URIs
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-rfc3986" title= "Uniform Resource Identifier (URI): Generic Syntax">
+RFC3986
+</a>
+</cite>
+].
+<span class="rfc2119-assertion" id="arch-rel-types">
+Extension
+relation
+types
+<em class="rfc2119">
+MUST
+</em>
+be
+compared
+as
+strings
+using
+ASCII
+case-insensitive
+comparison,
+(c.f.
+<a href= "https://infra.spec.whatwg.org/#ascii-case-insensitive">
+ASCII
+case
+insensitive
+</a>
+).
+(If
+they
+are
+serialized
+in
+a
+different
+format
+they
+are
+to
+be
+converted
+to
+URIs).
+</span>
+<span class= "rfc2119-assertion" id="arch-rel-type-lowercase">
+Nevertheless,
+all-lowercase
+URIs
+<em class="rfc2119">
+SHOULD
+</em>
+be
+used
+for
+extension
+relation
+types
+[
+<cite>
+<a class="bibref" data-link-type= "biblio" href="#bib-rfc8288" title= "Web Linking">
+RFC8288
+</a>
+</cite>
+].
+</span>
+</p>
+<p>
+In
+the
+Web
+of
+Things,
+<em>
+links
+</em>
+are
+used
+for
+<a href= "#dfn-wot-discovery" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-discovery-4">
+Discovery
+</a>
+and
+to
+express
+relations
+between
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-69">
+Things
+</a>
+(e.g.,
+hierarchical
+or
+functional)
+and
+relations
+to
+other
+documents
+on
+the
+Web
+(e.g.,
+documentation
+manuals
+or
+alternative
+representations
+such
+as
+CAD
+models).
+</p>
+</section>
+<section id="sec-hypermedia-forms">
+<div class="header-wrapper">
+<h4 id="x6-6-2-forms">
+<bdi class="secno">
+6.6.2
+</bdi>
+Forms
+</h4>
+<a class="self-link" href="#sec-hypermedia-forms" aria-label= "Permalink for Section 6.6.2">
+</a>
+</div>
+<p>
+Forms
+enable
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-consumer-30">
+Consumers
+</a>
+(or
+Web
+clients
+in
+the
+broader
+sense)
+to
+perform
+operations
+that
+go
+beyond
+dereferencing
+a
+URI
+(e.g.,
+to
+manipulate
+the
+state
+of
+a
+Thing).
+<a href="#dfn-consumer" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-consumer-31">
+Consumers
+</a>
+do
+so
+by
+<em>
+filling
+out
+</em>
+and
+<em>
+submitting
+</em>
+the
+form
+to
+its
+submission
+target.
+This
+usually
+requires
+more
+detailed
+information
+about
+the
+contents
+of
+the
+(request)
+message
+than
+a
+link
+can
+provide
+(e.g.,
+method,
+header
+fields,
+or
+other
+protocol
+options).
+Forms
+can
+be
+seen
+as
+a
+request
+template,
+where
+the
+provider
+pre-filled
+parts
+of
+the
+information
+according
+to
+its
+own
+interface
+and
+state,
+and
+left
+parts
+blank
+to
+be
+filled
+by
+the
+<a href="#dfn-consumer" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-32">
+Consumers
+</a>
+(or
+Web
+client
+in
+general).
+</p>
+<p>
+<abbr title="World Wide Web Consortium">
+W3C
+</abbr>
+WoT
+defines
+forms
+as
+new
+<a href="#dfn-hypermedia-control" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-hypermedia-control-5">
+hypermedia
+control
+</a>.
+Note
+that
+the
+definition
+in
+CoRAL
+is
+virtually
+identical,
+and
+hence
+compatible
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-coral" title= "The Constrained RESTful Application Language (CoRAL)">
+CoRAL
+</a>
+</cite>
+].
+In
+CoRAL
+a
+form
+is
+comprised
+of:
+</p>
+<ul>
+<li>
+a
+form
+context,
+</li>
+<li>
+an
+operation
+type,
+</li>
+<li>
+a
+submission
+target,
+</li>
+<li>
+a
+request
+method,
+and
+</li>
+<li>
+optionally
+form
+fields.
+</li>
+</ul>
+<p>
+A
+form
+can
+be
+viewed
+as
+a
+statement
+of
+"To
+perform
+an
+<code>
+operation
+type
+</code>
+operation
+on
+<code>
+form
+context
+</code>
+,
+issue
+a
+<code>
+request
+method
+</code>
+request
+to
+<code>
+submission
+target
+</code>
+"
+where
+the
+optional
+form
+fields
+may
+further
+describe
+the
+required
+request.
+</p>
+<p>
+<span class="rfc2119-assertion" id="arch-form-iris">
+Form
+contexts
+and
+submission
+targets
+<em class="rfc2119">
+MUST
+</em>
+both
+be
+Internationalized
+Resource
+Identifiers
+(IRIs)
+[
+<cite>
+<a class= "bibref" data-link-type="biblio" href="#bib-rfc3987" title= "Internationalized Resource Identifiers (IRIs)">
+RFC3987
+</a>
+</cite>
+].
+</span>
+However,
+in
+the
+common
+case,
+they
+will
+also
+be
+URIs
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-rfc3986" title= "Uniform Resource Identifier (URI): Generic Syntax">
+RFC3986
+</a>
+</cite>
+],
+because
+many
+protocols
+(such
+as
+HTTP)
+do
+not
+support
+IRIs.
+</p>
+<p>
+<span class="rfc2119-assertion" id="arch-form-iris2">
+Form
+context
+and
+submission
+target
+<em class="rfc2119">
+MAY
+</em>
+point
+to
+the
+same
+resource
+or
+different
+resources,
+where
+the
+submission
+target
+resource
+implements
+the
+operation
+for
+the
+context.
+</span>
+</p>
+<p>
+The
+operation
+type
+identifies
+the
+semantics
+of
+the
+operation.
+Operation
+types
+are
+denoted
+similar
+to
+link
+relation
+types.
+</p>
+<p>
+<span class="rfc2119-assertion" id="arch-op-request-method">
+The
+request
+method
+<em class="rfc2119">
+MUST
+</em>
+identify
+one
+method
+of
+the
+standard
+set
+of
+the
+protocol
+identified
+by
+the
+submission
+target
+URI
+scheme.
+</span>
+</p>
+<p>
+<span class="rfc2119-assertion" id= "arch-op-expected-request">
+Form
+fields
+are
+optional
+and
+<em class= "rfc2119">
+MAY
+</em>
+further
+specify
+the
+expected
+request
+message
+for
+the
+given
+operation.
+</span>
+Note
+that
+this
+is
+not
+limited
+to
+the
+payload,
+but
+may
+affect
+also
+protocol
+headers.
+<span class= "rfc2119-assertion" id="arch-op-form-fields-protocol">
+Form
+fields
+<em class="rfc2119">
+MAY
+</em>
+depend
+on
+the
+protocol
+used
+for
+the
+submission
+target
+as
+specified
+in
+the
+URI
+scheme.
+</span>
+Examples
+are
+HTTP
+header
+fields,
+CoAP
+options,
+the
+protocol-independent
+media
+type
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-rfc2046" title= "Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types">
+RFC2046
+</a>
+</cite>
+]
+including
+parameters
+(i.e.,
+full
+content
+type)
+for
+the
+request
+payload,
+or
+information
+about
+the
+expected
+response.
+</p>
+<div class="note" role="note" id="issue-container-generatedID-1">
+<div role="heading" class="note-title marker" id="h-note-1" aria-level="5">
+<span>
+Note
+</span>
+</div>
+<p class="">
+As
+of
+this
+specification,
+the
+well-known
+operation
+types
+are
+a
+fixed
+set
+that
+results
+from
+the
+WoT
+<a href= "#dfn-interaction-model" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-interaction-model-2">
+Interaction
+Model
+</a>.
+Other
+specifications
+may
+define
+further
+well-known
+operation
+types
+that
+are
+valid
+for
+their
+respective
+document
+format
+or
+form
+serialization.
+Later
+versions
+of
+this
+specification
+or
+another
+specification
+may
+set
+up
+an
+IANA
+registry
+in
+the
+future
+to
+enable
+extension
+and
+a
+more
+generic
+Web
+form
+model
+that
+may
+be
+applied
+beyond
+WoT
+specifications.
+</p>
+</div>
+</section>
+</section>
+<section id="sec-protocol-bindings">
+<div class="header-wrapper">
+<h3 id="x6-7-protocol-bindings">
+<bdi class="secno">
+6.7
+</bdi>
+Protocol
+Bindings
+</h3>
+<a class="self-link" href="#sec-protocol-bindings" aria-label= "Permalink for Section 6.7">
+</a>
+</div>
+<p>
+A
+<a href="#dfn-wot-protocol-binding" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-protocol-binding-3">
+Protocol
+Binding
+</a>
+is
+the
+mapping
+from
+an
+<a href="#dfn-interaction-affordance" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-interaction-affordance-16">
+Interaction
+Affordance
+</a>
+to
+concrete
+messages
+of
+a
+specific
+protocol
+such
+as
+HTTP
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-rfc7231" title= "Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">
+RFC7231
+</a>
+</cite>
+],
+CoAP
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-rfc7252" title= "The Constrained Application Protocol (CoAP)">
+RFC7252
+</a>
+</cite>
+],
+or
+MQTT
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-mqtt" title= "MQTT Version 3.1.1 Plus Errata 01">
+MQTT
+</a>
+</cite>
+].
+It
+informs
+the
+<a href="#dfn-consumer" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-consumer-33">
+Consumer
+</a>
+<em>
+how
+</em>
+to
+activate
+the
+<a href="#dfn-interaction-affordance" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-interaction-affordance-17">
+Interaction
+Affordance
+</a>
+through
+a
+network-facing
+interface.
+The
+<a href= "#dfn-wot-protocol-binding" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-wot-protocol-binding-4">
+Protocol
+Bindings
+</a>
+follow
+the
+Uniform
+Interface
+constraint
+of
+REST
+[
+<cite>
+<a class= "bibref" data-link-type="biblio" href="#bib-rest" title= "REST: Architectural Styles and the Design of Network-based Software Architectures">
+REST
+</a>
+</cite>
+]
+to
+support
+interoperability.
+Thus,
+not
+all
+communication
+protocols
+are
+eligible
+to
+implement
+<a href="#dfn-wot-protocol-binding" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-protocol-binding-5">
+Protocol
+Bindings
+</a>
+for
+<abbr title="World Wide Web Consortium">
+W3C
+</abbr>
+WoT;
+the
+requirements
+are
+given
+in
+the
+assertions
+below.
+</p>
+<p>
+In
+the
+door
+example
+given
+in
+<a href="#sec-affordances" class= "sec-ref">
+<bdi class="secno">
+6.2
+</bdi>
+Affordances
+</a>,
+the
+<a href="#dfn-wot-protocol-binding" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-protocol-binding-6">
+Protocol
+Binding
+</a>
+corresponds
+to
+the
+door
+handle
+at
+the
+level
+of
+knob
+vs
+lever,
+which
+suggests
+<em>
+how
+</em>
+the
+door
+can
+be
+opened.
+</p>
+<section id="hypermedia-driven">
+<div class="header-wrapper">
+<h4 id="x6-7-1-hypermedia-driven">
+<bdi class="secno">
+6.7.1
+</bdi>
+Hypermedia-driven
+</h4>
+<a class="self-link" href="#hypermedia-driven" aria-label= "Permalink for Section 6.7.1">
+</a>
+</div>
+<p>
+<span class="rfc2119-assertion" id="arch-hypermedia">
+Interaction
+Affordances
+<em class="rfc2119">
+MUST
+</em>
+include
+one
+or
+more
+Protocol
+Bindings.
+</span>
+<span class="rfc2119-assertion" id= "arch-hypermedia-protocol-binding">
+<a href= "#dfn-wot-protocol-binding" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-wot-protocol-binding-7">
+Protocol
+Bindings
+</a>
+<em class="rfc2119">
+MUST
+</em>
+be
+serialized
+as
+<a href= "#sec-hypermedia-controls">
+hypermedia
+controls
+</a>
+to
+be
+self-descriptive
+on
+how
+to
+activate
+the
+<a href= "#dfn-interaction-affordance" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-interaction-affordance-18">
+Interaction
+Affordance
+</a>.
+</span>
+The
+authority
+of
+the
+<a href= "#dfn-hypermedia-control" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-hypermedia-control-6">
+hypermedia
+controls
+</a>
+can
+be
+the
+<a href="#dfn-thing" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-thing-70">
+Thing
+</a>
+itself,
+producing
+the
+<a href="#dfn-td" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-td-6">
+TD
+</a>
+document
+at
+runtime
+(based
+on
+its
+current
+state
+and
+including
+network
+parameters
+such
+as
+its
+IP
+address)
+or
+serving
+it
+from
+memory
+with
+only
+the
+current
+network
+parameters
+inserted.
+The
+authority
+can
+also
+be
+an
+external
+entity
+that
+has
+full
+and
+up-to-date
+knowledge
+of
+the
+<a href="#dfn-thing" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-71">
+Thing
+</a>
+including
+its
+network
+parameters
+and
+internal
+structure
+(e.g.,
+software
+stack).
+This
+enables
+a
+loose
+coupling
+between
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-72">
+Things
+</a>
+and
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-consumer-34">
+Consumers
+</a>,
+allowing
+for
+an
+independent
+lifecycle
+and
+evolution.
+<span class= "rfc2119-assertion" id="arch-hypermedia-caching">
+The
+<a href= "#dfn-hypermedia-control" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-hypermedia-control-7">
+hypermedia
+controls
+</a>
+<em class="rfc2119">
+MAY
+</em>
+be
+cached
+outside
+the
+<a href= "#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-73">
+Thing
+</a>
+and
+used
+for
+offline
+processing
+if
+caching
+metadata
+is
+available
+to
+determine
+the
+freshness.
+</span>
+</p>
+</section>
+<section id="sec-arch-URIs">
+<div class="header-wrapper">
+<h4 id="x6-7-2-uris">
+<bdi class="secno">
+6.7.2
+</bdi>
+URIs
+</h4>
+<a class="self-link" href="#sec-arch-URIs" aria-label= "Permalink for Section 6.7.2">
+</a>
+</div>
+<p>
+Hypermedia
+controls
+rely
+on
+URIs
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href="#bib-rfc3986" title= "Uniform Resource Identifier (URI): Generic Syntax">
+RFC3986
+</a>
+</cite>
+]
+to
+identify
+link
+and
+submission
+targets.
+Thereby,
+the
+URI
+scheme
+(the
+first
+component
+up
+to
+":")
+identifies
+the
+communication
+protocol
+to
+be
+used
+for
+<a href="#dfn-interaction-affordance" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-interaction-affordance-19">
+Interaction
+Affordance
+</a>
+s
+with
+the
+Thing.
+<abbr title="World Wide Web Consortium">
+W3C
+</abbr>
+WoT
+refers
+to
+these
+protocols
+as
+<a href="#dfn-transport-protocol" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-transport-protocol-1">
+transport
+protocols
+</a>.
+</p>
+</section>
+</section>
+<section id="media-types">
+<div class="header-wrapper">
+<h3 id="x6-8-media-types">
+<bdi class="secno">
+6.8
+</bdi>
+Media
+Types
+</h3>
+<a class="self-link" href="#media-types" aria-label= "Permalink for Section 6.8">
+</a>
+</div>
+<p>
+<span class="rfc2119-assertion" id="arch-media-type">
+All
+data
+(a.k.a.
+content)
+exchanged
+when
+activating
+Interaction
+Affordances
+<em class="rfc2119">
+MUST
+</em>
+be
+identified
+by
+a
+media
+type
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-rfc2046" title= "Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types">
+RFC2046
+</a>
+</cite>
+]
+in
+the
+Protocol
+Binding.
+</span>
+Media
+types
+are
+labels
+to
+identify
+representation
+formats,
+for
+instance
+<code>
+application/json
+</code>
+for
+JSON
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-rfc8259" title= "The JavaScript Object Notation (JSON) Data Interchange Format">
+RFC8259
+</a>
+</cite>
+]
+or
+<code>
+application/cbor
+</code>
+for
+CBOR
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href="#bib-rfc7049" title= "Concise Binary Object Representation (CBOR)">
+RFC7049
+</a>
+</cite>
+].
+They
+are
+managed
+by
+IANA.
+</p>
+<p>
+Some
+media
+types
+might
+need
+additional
+parameters
+to
+fully
+specify
+the
+representation
+format
+used.
+Examples
+are
+<code>
+text/plain;
+charset=utf-8
+</code>
+or
+<code>
+application/ld+json;
+profile="http://www.w3.org/ns/json-ld#compacted"
+</code>.
+This
+needs
+to
+be
+considered
+in
+particular
+when
+describing
+data
+to
+be
+sent
+to
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-74">
+Things
+</a>.
+There
+might
+also
+be
+standardized
+transformations
+on
+the
+data
+such
+as
+content
+coding
+[
+<cite>
+<a class= "bibref" data-link-type="biblio" href="#bib-rfc7231" title= "Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">
+RFC7231
+</a>
+</cite>
+].
+<span class="rfc2119-assertion" id="arch-media-type-extra">
+Protocol
+Bindings
+<em class="rfc2119">
+MAY
+</em>
+have
+additional
+information
+that
+specifies
+representation
+formats
+in
+more
+detail
+than
+the
+media
+type
+alone.
+</span>
+</p>
+<p>
+Note
+that
+many
+media
+types
+only
+identify
+a
+generic
+serialization
+format
+that
+does
+not
+provide
+further
+semantics
+for
+its
+elements
+(e.g.,
+XML,
+JSON,
+CBOR).
+<span class="rfc2119-assertion" id= "arch-schema">
+Thus,
+the
+Interaction
+Affordance
+for
+structured
+data
+types
+<em class="rfc2119">
+SHOULD
+</em>
+be
+associated
+with
+a
+<em>
+<a href="#dfn-data-schema" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-data-schema-4">
+data
+schema
+</a>
+</em>
+to
+provide
+more
+detailed
+syntactic
+metadata
+for
+the
+data
+exchanged.
+</span>
+Details
+are
+further
+described
+in
+the
+<a href= "#dfn-wot-thing-description" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-wot-thing-description-10">
+WoT
+Thing
+Description
+</a>
+specification
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href="#bib-wot-thing-description" title= "Web of Things (WoT) Thing Description 1.1">
+WOT-THING-DESCRIPTION
+</a>
+</cite>
+].
+</p>
+</section>
+<section id="sec-i18n">
+<div class="header-wrapper">
+<h3 id="x6-9-internationalization">
+<bdi class="secno">
+6.9
+</bdi>
+Internationalization
+</h3>
+<a class="self-link" href="#sec-i18n" aria-label= "Permalink for Section 6.9">
+</a>
+</div>
+<p>
+Web
+of
+Things
+support
+interoperable
+internationalization
+and
+allows
+to
+use
+to
+work
+with
+multilingual
+data
+such
+as
+for
+User
+Interfaces.
+The
+design
+and
+implementation
+of
+multilingual
+Web
+of
+Things
+implementations
+is
+guided
+by
+the
+Thing
+Description
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-wot-thing-description" title= "Web of Things (WoT) Thing Description 1.1">
+WOT-THING-DESCRIPTION
+</a>
+</cite>
+]
+specification.
+It
+describes
+how
+human-readable
+text
+in
+different
+languages
+can
+be
+applied
+based
+on
+established
+standards
+such
+as
+from
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-json-ld" title="JSON-LD 1.0">
+JSON-LD
+</a>
+</cite>
+]
+and
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href="#bib-bcp47" title="Tags for Identifying Languages">
+BCP47
+</a>
+</cite>
+].
+</p>
+</section>
+<section id="sec-wot-servient-architecture-high-level">
+<div class="header-wrapper">
+<h3 id="x6-10-wot-system-components-and-their-interconnectivity">
+<bdi class="secno">
+6.10
+</bdi>
+WoT
+System
+Components
+and
+their
+Interconnectivity
+</h3>
+<a class="self-link" href= "#sec-wot-servient-architecture-high-level" aria-label= "Permalink for Section 6.10">
+</a>
+</div>
+<p>
+Section
+<a href="#sec-architecture-overview" class= "sec-ref">
+<bdi class="secno">
+6.1
+</bdi>
+Fundamental
+Concepts
+</a>
+described
+the
+WoT
+architecture
+in
+terms
+of
+the
+abstract
+WoT
+architecture
+components
+such
+as
+<a href="#dfn-thing" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-75">
+Things
+</a>,
+<a href="#dfn-consumer" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-35">
+Consumers
+</a>
+and
+<a href= "#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-11">
+Intermediaries
+</a>.
+When
+those
+components
+are
+implemented
+as
+a
+software
+stack
+to
+take
+a
+specific
+role
+in
+the
+WoT
+architecture,
+such
+software
+stacks
+are
+called
+<a href="#dfn-servient" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-servient-1">
+Servients
+</a>.
+Systems
+that
+are
+based
+on
+the
+WoT
+architecture
+involve
+<a href="#dfn-servient" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-servient-2">
+Servients
+</a>,
+which
+are
+communicating
+with
+each
+other
+to
+achieve
+the
+goals
+of
+a
+system.
+</p>
+<p>
+This
+section
+uses
+system
+configuration
+diagrams
+to
+illustrate
+how
+<a href="#dfn-servient" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-servient-3">
+Servients
+</a>
+work
+together
+to
+build
+systems
+based
+on
+the
+WoT
+architecture.
+</p>
+<p>
+A
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-76">
+Thing
+</a>
+can
+be
+implemented
+by
+a
+<a href="#dfn-servient" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-servient-4">
+Servient
+</a>.
+In
+a
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-77">
+Thing
+</a>,
+a
+<a href="#dfn-servient" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-servient-5">
+Servient
+</a>
+software
+stack
+contains
+a
+representation
+of
+a
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-78">
+Thing
+</a>
+called
+<a href="#dfn-exposed-thing" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-exposed-thing-2">
+Exposed
+Thing
+</a>,
+and
+makes
+its
+<a href="#dfn-wot-interface" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-interface-5">
+WoT
+Interface
+</a>
+available
+to
+<a href="#dfn-consumer" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-36">
+Consumers
+</a>
+of
+the
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-79">
+Thing
+</a>.
+This
+<a href="#dfn-exposed-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-exposed-thing-3">
+Exposed
+Thing
+</a>
+may
+be
+used
+by
+other
+software
+components
+on
+the
+<a href="#dfn-servient" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-servient-6">
+Servient
+</a>
+(e.g.,
+applications)
+to
+implement
+the
+behavior
+of
+the
+thing.
+</p>
+<figure id="servient-thing-exposedThing">
+<img src= "images/architecture/servient-thing-exposedThing.png" srcset= "images/architecture/servient-thing-exposedThing.svg" class= "wot-arch-diagram" alt="servient as a thing" />
+<figcaption>
+<a class="self-link" href= "#servient-thing-exposedThing">
+Figure
+<bdi class= "figno">
+24
+</bdi>
+</a>
+<span class="fig-title">
+Servient
+as
+a
+Thing
+</span>
+</figcaption>
+</figure>
+<p>
+On
+the
+other
+hand,
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-consumer-37">
+Consumers
+</a>
+are
+always
+implemented
+by
+<a href="#dfn-servient" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-servient-7">
+Servients
+</a>,
+as
+they
+must
+be
+able
+to
+process
+the
+<a href="#dfn-thing-description" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-description-19">
+Thing
+Description
+</a>
+(TD)
+format
+and
+must
+have
+a
+protocol
+stack
+that
+can
+be
+configured
+through
+<a href="#dfn-wot-protocol-binding" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-protocol-binding-8">
+Protocol
+Binding
+</a>
+information
+contained
+in
+the
+TDs.
+</p>
+<p>
+In
+a
+<a href="#dfn-consumer" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-consumer-38">
+Consumer
+</a>,
+a
+<a href= "#dfn-servient" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-servient-8">
+Servient
+</a>
+software
+stack
+provides
+a
+representation
+of
+a
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-80">
+Thing
+</a>
+called
+<a href="#dfn-consumed-thing" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-consumed-thing-1">
+Consumed
+Thing
+</a>,
+and
+makes
+it
+available
+to
+those
+applications
+running
+on
+the
+<a href= "#dfn-servient" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-servient-9">
+Servient
+</a>
+that
+need
+to
+process
+TDs
+to
+interact
+with
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-81">
+Things
+</a>.
+</p>
+<figure id="servient-consumer-consumedThing">
+<img src= "images/architecture/servient-consumer-consumedThing.png" srcset= "images/architecture/servient-consumer-consumedThing.svg" class= "wot-arch-diagram" alt="servient as a consumer" />
+<figcaption>
+<a class="self-link" href= "#servient-consumer-consumedThing">
+Figure
+<bdi class= "figno">
+25
+</bdi>
+</a>
+<span class="fig-title">
+Servient
+as
+a
+Consumer
+</span>
+</figcaption>
+</figure>
+<p>
+A
+<a href="#dfn-consumed-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-consumed-thing-2">
+Consumed
+Thing
+</a>
+instance
+in
+the
+<a href="#dfn-servient" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-servient-10">
+Servient
+</a>
+software
+stack
+serves
+to
+separate
+the
+protocol
+level
+complexity
+from
+applications.
+It
+is
+communicating
+with
+<a href="#dfn-exposed-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-exposed-thing-4">
+Exposed
+Things
+</a>
+on
+behalf
+of
+the
+application.
+</p>
+<p>
+Similarly,
+an
+<a href="#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-12">
+Intermediary
+</a>
+is
+yet
+another
+WoT
+architecture
+component
+implemented
+by
+a
+<a href="#dfn-servient" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-servient-11">
+Servient
+</a>.
+An
+<a href= "#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-13">
+Intermediary
+</a>
+is
+located
+between
+a
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-82">
+Thing
+</a>
+and
+its
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-39">
+Consumers
+</a>,
+performing
+the
+roles
+of
+both
+a
+<a href="#dfn-consumer" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-consumer-40">
+Consumer
+</a>
+(to
+the
+Thing)
+and
+a
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-83">
+Thing
+</a>
+(to
+the
+Consumers).
+In
+an
+<a href= "#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-14">
+Intermediary
+</a>,
+a
+<a href= "#dfn-servient" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-servient-12">
+Servient
+</a>
+software
+stack
+contains
+the
+representations
+of
+both
+a
+<a href="#dfn-consumer" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-41">
+Consumer
+</a>
+(
+<a href= "#dfn-consumed-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumed-thing-3">
+Consumed
+Thing
+</a>
+)
+and
+a
+<a href= "#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-84">
+Thing
+</a>
+(
+<a href="#dfn-exposed-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-exposed-thing-5">
+Exposed
+Thing
+</a>
+).
+</p>
+<figure id="servient-intermediary">
+<img src= "images/architecture/servient-intermediary.png" srcset= "images/architecture/servient-intermediary.svg" class= "wot-arch-diagram" alt="servient as an intermediary" />
+<figcaption>
+<a class="self-link" href= "#servient-intermediary">
+Figure
+<bdi class="figno">
+26
+</bdi>
+</a>
+<span class="fig-title">
+Servient
+as
+an
+Intermediary
+</span>
+</figcaption>
+</figure>
+<section id="direct-communication">
+<div class="header-wrapper">
+<h4 id="x6-10-1-direct-communication">
+<bdi class= "secno">
+6.10.1
+</bdi>
+Direct
+Communication
+</h4>
+<a class="self-link" href="#direct-communication" aria-label= "Permalink for Section 6.10.1">
+</a>
+</div>
+<p>
+<a href="#high-level-application-device" class="fig-ref" title= "High-level architecture of Consumer and Thing">
+Figure
+<bdi class= "">
+27
+</bdi>
+</a>
+shows
+direct
+communication
+between
+a
+<a href= "#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-85">
+Thing
+</a>,
+which
+is
+exposing
+<a href= "#dfn-interaction-affordance" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-interaction-affordance-20">
+Interaction
+Affordances
+</a>
+through
+<a href="#dfn-thing-description" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-description-20">
+Thing
+Descriptions
+</a>,
+and
+a
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-consumer-42">
+Consumer
+</a>
+that
+uses
+the
+<a href= "#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-86">
+Thing
+</a>
+by
+means
+of
+the
+<a href= "#dfn-interaction-affordance" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-interaction-affordance-21">
+Interaction
+Affordances
+</a>.
+Direct
+communication
+applies
+when
+both
+<a href= "#dfn-servient" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-servient-13">
+Servients
+</a>
+use
+the
+same
+network
+protocol(s)
+and
+are
+accessible
+to
+each
+other.
+</p>
+<figure id="high-level-application-device">
+<img src= "images/architecture/servient-consumer-thing.png" srcset= "images/architecture/servient-consumer-thing.svg" class= "wot-arch-diagram" alt= "high-level architecture of consumer and thing" />
+<figcaption>
+<a class="self-link" href= "#high-level-application-device">
+Figure
+<bdi class= "figno">
+27
+</bdi>
+</a>
+<span class="fig-title">
+High-level
+architecture
+of
+Consumer
+and
+Thing
+</span>
+</figcaption>
+</figure>
+<p>
+An
+<a href="#dfn-exposed-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-exposed-thing-6">
+Exposed
+Thing
+</a>
+is
+the
+software
+representation
+of
+a
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-87">
+Thing
+</a>
+abstraction,
+serving
+a
+<a href= "#dfn-wot-interface" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-interface-6">
+WoT
+Interface
+</a>
+of
+the
+<a href= "#dfn-interaction-affordance" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-interaction-affordance-22">
+Interaction
+Affordances
+</a>
+provided
+by
+the
+<a href="#dfn-thing" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-88">
+Thing
+</a>.
+</p>
+<p>
+A
+<a href="#dfn-consumed-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-consumed-thing-4">
+Consumed
+Thing
+</a>
+is
+the
+software
+representation
+of
+a
+remote
+<a href= "#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-89">
+Thing
+</a>
+being
+consumed
+by
+a
+<a href= "#dfn-consumer" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-43">
+Consumer
+</a>,
+serving
+as
+the
+interface
+to
+the
+remote
+<a href="#dfn-thing" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-thing-90">
+Thing
+</a>
+for
+the
+applications.
+A
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-consumer-44">
+Consumer
+</a>
+can
+generate
+a
+<a href= "#dfn-consumed-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumed-thing-5">
+Consumed
+Thing
+</a>
+instance
+by
+parsing
+and
+processing
+a
+<a href="#dfn-td" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-td-7">
+TD
+</a>
+document.
+Interactions
+between
+a
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-consumer-45">
+Consumer
+</a>
+and
+a
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-91">
+Thing
+</a>
+are
+performed
+by
+the
+<a href= "#dfn-consumed-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumed-thing-6">
+Consumed
+Thing
+</a>
+and
+the
+<a href= "#dfn-exposed-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-exposed-thing-7">
+Exposed
+Thing
+</a>
+exchanging
+messages
+over
+a
+direct
+network
+connection
+between
+them.
+</p>
+</section>
+<section id="indirect-communication">
+<div class="header-wrapper">
+<h4 id="x6-10-2-indirect-communication">
+<bdi class= "secno">
+6.10.2
+</bdi>
+Indirect
+Communication
+</h4>
+<a class="self-link" href="#indirect-communication" aria-label= "Permalink for Section 6.10.2">
+</a>
+</div>
+<p>
+In
+<a href="#high-level-application-intermediary-device-new" class="fig-ref" title= "High-level architecture with Intermediary">
+Figure
+<bdi class= "">
+28
+</bdi>
+</a>,
+a
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-consumer-46">
+Consumer
+</a>
+and
+a
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-92">
+Thing
+</a>
+connect
+to
+each
+other
+via
+an
+<a href="#dfn-intermediary" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-intermediary-15">
+Intermediary
+</a>.
+An
+<a href="#dfn-intermediary" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-intermediary-16">
+Intermediary
+</a>
+is
+required
+if
+the
+<a href="#dfn-servient" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-servient-14">
+Servients
+</a>
+use
+different
+protocols
+or
+if
+they
+are
+on
+different
+networks
+that
+require
+authentication
+and
+provide
+access
+control
+(e.g.
+firewalls).
+</p>
+<figure id="high-level-application-intermediary-device-new">
+<img src= "images/architecture/servient-consumer-intermediary-thing.png" srcset= "images/architecture/servient-consumer-intermediary-thing.svg" class="wot-arch-diagram" alt= "high-level architecture with intermediary" />
+<figcaption>
+<a class="self-link" href= "#high-level-application-intermediary-device-new">
+Figure
+<bdi class="figno">
+28
+</bdi>
+</a>
+<span class="fig-title">
+High-level
+architecture
+with
+Intermediary
+</span>
+</figcaption>
+</figure>
+<p>
+An
+<a href="#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-17">
+Intermediary
+</a>
+combines
+<a href= "#dfn-exposed-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-exposed-thing-8">
+Exposed
+Thing
+</a>
+and
+<a href= "#dfn-consumed-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumed-thing-7">
+Consumed
+Thing
+</a>
+functionality.
+The
+functionality
+of
+<a href="#dfn-intermediary" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-18">
+Intermediaries
+</a>
+includes
+relaying
+messages
+for
+the
+<a href="#dfn-interaction-affordance" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-interaction-affordance-23">
+Interaction
+Affordance
+</a>
+s
+between
+a
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-consumer-47">
+Consumer
+</a>
+and
+a
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-93">
+Thing
+</a>,
+optionally
+caching
+the
+<a href= "#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-94">
+Thing
+</a>
+'s
+data
+for
+faster
+response,
+and
+transforming
+communication
+when
+the
+functionality
+of
+the
+<a href= "#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-95">
+Thing
+</a>
+is
+extended
+by
+the
+<a href= "#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-19">
+Intermediary
+</a>.
+In
+an
+<a href= "#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-20">
+Intermediary
+</a>,
+a
+<a href= "#dfn-consumed-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumed-thing-8">
+Consumed
+Thing
+</a>
+creates
+a
+proxy
+object
+of
+the
+<a href="#dfn-exposed-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-exposed-thing-9">
+Exposed
+Thing
+</a>
+of
+a
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-96">
+Thing
+</a>,
+and
+a
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-consumer-48">
+Consumer
+</a>
+can
+access
+the
+proxy
+object
+(i.e.,
+the
+<a href="#dfn-exposed-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-exposed-thing-10">
+Exposed
+Thing
+</a>
+of
+the
+<a href="#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-21">
+Intermediary
+</a>
+)
+through
+its
+own
+<a href="#dfn-consumed-thing" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-consumed-thing-9">
+Consumed
+Thing
+</a>.
+</p>
+<p>
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-consumer-49">
+Consumer
+</a>
+and
+<a href= "#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-22">
+Intermediary
+</a>
+can
+communicate
+in
+a
+different
+protocol
+than
+<a href="#dfn-intermediary" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-23">
+Intermediary
+</a>
+and
+<a href= "#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-97">
+Thing
+</a>.
+For
+example,
+an
+<a href= "#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-24">
+Intermediary
+</a>
+can
+provide
+a
+bridge
+between
+a
+<a href="#dfn-thing" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-thing-98">
+Thing
+</a>
+that
+uses
+CoAP
+and
+the
+application
+of
+a
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-consumer-50">
+Consumer
+</a>
+that
+uses
+HTTP.
+</p>
+<p>
+Even
+when
+there
+are
+multiple
+different
+protocols
+used
+between
+<a href="#dfn-intermediary" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-intermediary-25">
+Intermediary
+</a>
+and
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-99">
+Things
+</a>,
+<a href="#dfn-consumer" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-51">
+Consumer
+</a>
+can
+indirectly
+communicate
+with
+those
+<a href="#dfn-thing" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-thing-100">
+Things
+</a>
+using
+a
+single
+protocol
+through
+the
+<a href="#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-26">
+Intermediary
+</a>.
+The
+same
+is
+true
+for
+the
+authentication.
+The
+<a href="#dfn-consumed-thing" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumed-thing-10">
+Consumed
+Thing
+</a>
+of
+a
+<a href= "#dfn-consumer" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-52">
+Consumer
+</a>
+only
+needs
+to
+authenticate
+with
+the
+<a href="#dfn-exposed-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-exposed-thing-11">
+Exposed
+Things
+</a>
+of
+the
+<a href="#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-27">
+Intermediary
+</a>
+using
+a
+single
+security
+mechanism,
+while
+the
+<a href="#dfn-intermediary" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-28">
+Intermediary
+</a>
+might
+need
+multiple
+security
+mechanism
+to
+authenticate
+with
+different
+<a href= "#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-101">
+Things
+</a>.
+</p>
+<p>
+Usually,
+an
+<a href="#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-29">
+Intermediary
+</a>
+generates
+the
+<a href="#dfn-thing-description" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-description-21">
+Thing
+Description
+</a>
+for
+its
+proxy
+object
+based
+on
+the
+<a href= "#dfn-thing-description" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-description-22">
+Thing
+Description
+</a>
+of
+the
+originating
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-102">
+Thing
+</a>.
+Depending
+on
+the
+requirements
+of
+the
+use
+cases,
+the
+TD
+for
+the
+proxy
+object
+may
+either
+use
+the
+same
+identifier
+as
+the
+TD
+of
+the
+original
+<a href="#dfn-thing" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-thing-103">
+Thing
+</a>,
+or
+it
+gets
+assigned
+a
+new
+identifier.
+<span class="rfc2119-assertion" id= "arch-intermediary-td-extra-protocols">
+If
+necessary,
+a
+TD
+generated
+by
+an
+<a href="#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-30">
+Intermediary
+</a>
+<em class= "rfc2119">
+MAY
+</em>
+contain
+interfaces
+for
+other
+communication
+protocols.
+</span>
+</p>
+</section>
+</section>
+</section>
+<section id="sec-building-blocks" class="informative">
+<div class="header-wrapper">
+<h2 id="x7-wot-building-blocks">
+<bdi class="secno">
+7.
+</bdi>
+WoT
+Building
+Blocks
+</h2>
+<a class="self-link" href="#sec-building-blocks" aria-label= "Permalink for Section 7.">
+</a>
+</div>
+<p>
+<em>
+This
+section
+is
+non-normative.
+</em>
+</p>
+<p>
+The
+Web
+of
+Things
+(WoT)
+building
+blocks
+allow
+the
+implementation
+of
+systems
+that
+conform
+with
+the
+abstract
+WoT
+Architecture.
+The
+specifics
+of
+these
+building
+blocks
+are
+defined
+in
+separate
+specifications;
+this
+section
+provides
+an
+overview
+and
+a
+summary.
+</p>
+<p>
+The
+WoT
+building
+blocks
+support
+each
+of
+the
+architectural
+aspects
+of
+a
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-104">
+Thing
+</a>
+discussed
+in
+<a href="#sec-web-thing" class="sec-ref">
+<bdi class= "secno">
+6.3
+</bdi>
+Web
+Thing
+</a>
+and
+depicted
+in
+<a href= "#arch-webthing" class="fig-ref" title= "Architectural Aspects of a Thing">
+Figure
+<bdi class= "">
+20
+</bdi>
+</a>.
+The
+individual
+building
+blocks
+are
+shown
+in
+the
+context
+of
+an
+abstract
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-105">
+Thing
+</a>
+in
+<a href="#arch-building-blocks" class="fig-ref" title= "Relationship of WoT Building Blocks to the Architectural Aspects of a Thing.">
+Figure
+<bdi class="">
+29
+</bdi>
+</a>.
+This
+is
+an
+abstract
+view
+and
+does
+not
+represent
+any
+particular
+implementation;
+instead
+it
+illustrates
+the
+relationship
+between
+the
+building
+blocks
+and
+the
+main
+architectural
+aspects
+of
+a
+<a href="#dfn-thing" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-106">
+Thing
+</a>.
+In
+this
+figure
+the
+WoT
+building
+blocks
+are
+highlighted
+with
+black
+outlines.
+The
+<a href= "#dfn-wot-thing-description" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-wot-thing-description-11">
+WoT
+Thing
+Description
+</a>
+is
+a
+key
+building
+block
+that
+provides
+metadata
+describing
+a
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-107">
+Thing
+</a>
+and
+its
+network
+interface.
+Security,
+a
+cross-cutting
+concern,
+is
+separated
+into
+public
+and
+protected
+private
+components.
+The
+<a href= "#dfn-wot-scripting-api" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-scripting-api-2">
+WoT
+Scripting
+API
+</a>
+is
+optional
+and
+the
+<a href="#dfn-wot-binding-templates" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-binding-templates-1">
+Binding
+Templates
+</a>
+are
+informative.
+The
+<a href="#dfn-wot-discovery" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-discovery-5">
+WoT
+Discovery
+</a>
+building
+block
+defines
+mechanisms
+for
+distributing
+<a href="#dfn-thing-description" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-description-23">
+Thing
+Descriptions
+</a>
+;
+a
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-108">
+Thing
+</a>
+can
+provide
+<a href="#dfn-thing-description" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-description-24">
+Thing
+Descriptions
+</a>
+directly,
+or
+they
+can
+be
+provided
+by
+a
+<a href= "#dfn-wot-thing-description-directory" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-thing-description-directory-8">
+Thing
+Description
+Directory
+</a>
+service.
+</p>
+<figure id="arch-building-blocks">
+<img src= "images/bblocks/abstract2.png" srcset= "images/bblocks/abstract2.svg" class="wot-arch-diagram" alt= "wot building blocks" />
+<figcaption>
+<a class="self-link" href= "#arch-building-blocks">
+Figure
+<bdi class="figno">
+29
+</bdi>
+</a>
+<span class="fig-title">
+Relationship
+of
+WoT
+Building
+Blocks
+to
+the
+Architectural
+Aspects
+of
+a
+Thing.
+</span>
+</figcaption>
+</figure>
+<p>
+In
+the
+following
+sections
+we
+will
+provide
+additional
+information
+on
+each
+WoT
+building
+block:
+the
+<a href= "#sec-thing-description">
+WoT
+Thing
+Description
+</a>,
+the
+<a href= "#sec-discovery">
+WoT
+Discovery
+</a>
+mechanisms,
+the
+<a href= "#sec-binding-templates">
+WoT
+Binding
+Templates
+</a>,
+and
+the
+<a href="#sec-scripting-api">
+WoT
+Scripting
+API
+</a>.
+Security,
+although
+it
+is
+a
+cross-cutting
+concern,
+can
+be
+considered
+an
+additional
+building
+block.
+</p>
+<section id="sec-thing-description">
+<div class="header-wrapper">
+<h3 id="x7-1-wot-thing-description">
+<bdi class="secno">
+7.1
+</bdi>
+WoT
+Thing
+Description
+</h3>
+<a class="self-link" href="#sec-thing-description" aria-label= "Permalink for Section 7.1">
+</a>
+</div>
+<p>
+The
+<a href="#dfn-wot-thing-description" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-thing-description-12">
+WoT
+Thing
+Description
+</a>
+(TD)
+specification
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href="#bib-wot-thing-description" title= "Web of Things (WoT) Thing Description 1.1">
+WOT-THING-DESCRIPTION
+</a>
+</cite>
+]
+defines
+an
+<em>
+information
+model
+</em>
+based
+on
+a
+semantic
+vocabulary
+and
+a
+<em>
+serialized
+representation
+based
+on
+JSON
+</em>.
+<a href="#dfn-td" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-td-8">
+TDs
+</a>
+provide
+rich
+metadata
+for
+<a href= "#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-109">
+Things
+</a>
+in
+a
+way
+that
+is
+both
+human-readable
+and
+machine-readable.
+Both
+the
+information
+model
+and
+the
+representation
+format
+of
+<a href="#dfn-td" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-td-9">
+TDs
+</a>
+are
+aligned
+with
+Linked
+Data
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-linked-data" title= "Linked Data Design Issues">
+LINKED-DATA
+</a>
+</cite>
+],
+so
+that
+besides
+raw
+JSON
+processing,
+implementations
+may
+choose
+to
+make
+use
+of
+JSON-LD
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-json-ld11" title="JSON-LD 1.1">
+JSON-LD11
+</a>
+</cite>
+]
+and
+graph
+databases
+to
+enable
+powerful
+semantic
+processing
+of
+the
+metadata.
+</p>
+<p>
+A
+<a href="#dfn-thing-description" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-description-25">
+Thing
+Description
+</a>
+describes
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-110">
+Thing
+</a>
+instances
+with
+general
+metadata
+such
+as
+name,
+ID,
+descriptions,
+and
+also
+can
+provide
+relation
+metadata
+through
+links
+to
+related
+<a href= "#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-111">
+Things
+</a>
+or
+other
+documents.
+<a href= "#dfn-td" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-td-10">
+TDs
+</a>
+also
+contain
+<a href= "#dfn-interaction-affordance" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-interaction-affordance-24">
+Interaction
+Affordance
+</a>
+metadata
+based
+on
+the
+interaction
+model
+defined
+in
+<a href="#sec-interaction-model" class="sec-ref">
+<bdi class= "secno">
+6.5
+</bdi>
+Interaction
+Model
+</a>
+;
+<a href= "#dfn-public-security-metadata" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-public-security-metadata-2">
+Public
+Security
+Metadata
+</a>
+;
+and
+communications
+metadata
+defining
+<a href= "#dfn-wot-protocol-binding" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-wot-protocol-binding-9">
+Protocol
+Bindings
+</a>.
+The
+<a href="#dfn-td" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-td-11">
+TD
+</a>
+can
+be
+seen
+as
+the
+<em>
+index.html
+for
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-112">
+Things
+</a>
+</em>,
+as
+it
+provides
+the
+entry
+point
+to
+learn
+about
+the
+services
+and
+related
+resources
+provided
+by
+a
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-113">
+Thing
+</a>,
+both
+of
+which
+are
+described
+using
+<a href="#dfn-hypermedia-control" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-hypermedia-control-8">
+hypermedia
+controls
+</a>.
+</p>
+<p>
+For
+semantic
+interoperability,
+<a href="#dfn-td" class= "internalDFN" data-link-type="dfn" id="ref-for-dfn-td-12">
+TDs
+</a>
+may
+make
+use
+of
+a
+<a href="#dfn-domain-specific-vocabulary" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-domain-specific-vocabulary-1">
+domain-specific
+vocabulary
+</a>,
+for
+which
+explicit
+extension
+points
+are
+provided.
+However,
+development
+of
+any
+particular
+<a href= "#dfn-domain-specific-vocabulary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-domain-specific-vocabulary-2">
+domain-specific
+vocabulary
+</a>
+is
+currently
+out-of-scope
+of
+the
+<abbr title= "World Wide Web Consortium">
+W3C
+</abbr>
+WoT
+standardization
+activity.
+</p>
+<p>
+Three
+examples
+of
+potentially
+useful
+external
+IoT
+vocabularies
+are
+SAREF
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-saref" title= "Smart Appliances REFerence (SAREF) ontology">
+SAREF
+</a>
+</cite>
+],
+Schema
+Extensions
+for
+IoT
+[
+<cite>
+<a class="bibref" data-link-type= "biblio" href="#bib-iot-schema-org" title= "Schema Extensions for IoT Community Group">
+IOT-SCHEMA-ORG
+</a>
+</cite>
+],
+and
+the
+<abbr title="World Wide Web Consortium">
+W3C
+</abbr>
+Semantic
+Sensor
+Network
+ontology
+[
+<cite>
+<a class="bibref" data-link-type= "biblio" href="#bib-vocab-ssn" title= "Semantic Sensor Network Ontology">
+VOCAB-SSN
+</a>
+</cite>
+].
+Use
+of
+such
+external
+vocabularies
+in
+<a href="#dfn-td" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-td-13">
+TDs
+</a>
+is
+optional.
+In
+the
+future
+additional
+<a href="#dfn-domain-specific-vocabulary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-domain-specific-vocabulary-3">
+domain-specific
+vocabularies
+</a>
+may
+be
+developed
+and
+used
+with
+<a href="#dfn-td" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-td-14">
+TDs
+</a>.
+</p>
+<p>
+Overall,
+the
+<a href="#dfn-wot-thing-description" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-thing-description-13">
+WoT
+Thing
+Description
+</a>
+building
+block
+fosters
+interoperability
+in
+two
+ways:
+First,
+<a href="#dfn-td" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-td-15">
+TDs
+</a>
+enable
+machine-to-machine
+communication
+in
+the
+Web
+of
+Things.
+Second,
+<a href="#dfn-td" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-td-16">
+TDs
+</a>
+can
+serve
+as
+a
+common,
+uniform
+format
+for
+developers
+to
+document
+and
+retrieve
+all
+the
+details
+necessary
+to
+create
+applications
+that
+can
+access
+IoT
+devices
+and
+make
+use
+of
+their
+data.
+</p>
+<p>
+TDs
+must
+be
+known
+or
+accessible
+to
+be
+useful
+to
+other
+systems
+and
+devices.
+The
+<a href="#sec-discovery">
+WoT
+Discovery
+</a>
+building
+block,
+described
+in
+more
+detail
+below,
+defines
+mechanisms
+by
+which
+this
+may
+be
+accomplished
+for
+both
+self-describing
+devices
+and
+for
+situations
+(brownfield
+devices,
+constrained
+devices,
+devices
+with
+specialized
+protocols,
+sleeping
+devices,
+etc.)
+in
+which
+having
+a
+separate
+service
+providing
+the
+TD
+is
+more
+suitable.
+</p>
+</section>
+<section id="sec-thing-model">
+<div class="header-wrapper">
+<h3 id="x7-2-thing-model">
+<bdi class="secno">
+7.2
+</bdi>
+Thing
+Model
+</h3>
+<a class="self-link" href="#sec-thing-model" aria-label= "Permalink for Section 7.2">
+</a>
+</div>
+<p>
+The
+<a href="#dfn-wot-thing-model" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-thing-model-19">
+Thing
+Model
+</a>
+defines
+a
+template-based
+model
+for
+<a href= "#dfn-thing-description" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-description-26">
+Thing
+Description
+</a>
+instances.
+A
+<a href="#dfn-wot-thing-model" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-thing-model-20">
+Thing
+Model
+</a>
+has
+no
+instance
+specific
+and
+only
+partial
+communication-
+and
+security-based
+information.
+This
+kind
+of
+information
+is
+supplemented
+by
+the
+creation
+of
+<a href="#dfn-thing-description" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-description-27">
+Thing
+Description
+</a>
+instantiation.
+</p>
+<p>
+A
+<a href="#dfn-wot-thing-model" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-thing-model-21">
+Thing
+Model
+</a>
+mainly
+describes
+the
+<a href="#dfn-property" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-property-7">
+Properties
+</a>,
+<a href="#dfn-action" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-action-6">
+Actions
+</a>,
+and
+<a href="#dfn-event" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-event-7">
+Events
+</a>
+and
+common
+metadata
+which
+then
+are
+available
+in
+all
+instantiated
+<a href="#dfn-thing-description" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-description-28">
+Thing
+Descriptions
+</a>.
+This
+paradigm
+can
+be
+compared
+with
+abstract
+class
+or
+interface
+definitions
+(~Thing
+Model)
+in
+object-oriented
+programming
+to
+create
+objects
+(~Thing
+Descriptions).Such
+<a href="#dfn-wot-thing-model" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-thing-model-22">
+Thing
+Models
+</a>
+are
+relevant
+for,
+e.g.,
+mass
+production
+of
+IoT
+devices,
+onboarding
+scenarios
+as
+in
+cloud
+services,
+or
+to
+simulate
+<a href="#dfn-device" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-device-5">
+Devices
+</a>
+that
+have
+not
+yet
+been
+developed.
+</p>
+</section>
+<section id="wot-profiles">
+<div class="header-wrapper">
+<h3 id="x7-3-profiles">
+<bdi class="secno">
+7.3
+</bdi>
+Profiles
+</h3>
+<a class="self-link" href="#wot-profiles" aria-label= "Permalink for Section 7.3">
+</a>
+</div>
+<div class="note" role="note" id="issue-container-generatedID-2">
+<div role="heading" class="note-title marker" id="h-note-2" aria-level="4">
+<span>
+Note
+</span>
+</div>
+<p class="">
+Currently,
+the
+<a href="#dfn-wot-profile" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-profile-1">
+WoT
+Profile
+</a>
+specification
+has
+only
+been
+published
+as
+a
+Working
+Draft.
+</p>
+</div>
+<p>
+The
+<a href="#dfn-wot-profile" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-profile-2">
+WoT
+Profile
+</a>
+Specification
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href="#bib-wot-profile" title= "Web of Things (WoT) Profile">
+WOT-PROFILE
+</a>
+</cite>
+]
+defines
+Profiles
+that
+enable
+<em>
+out
+of
+the
+box
+interoperability
+</em>
+among
+things
+and
+devices.
+Out
+of
+the
+box
+interoperability
+implies
+that
+devices
+can
+be
+integrated
+into
+various
+application
+scenarios
+without
+deep
+level
+adaptations.
+Typically
+only
+minor
+configuration
+operations
+are
+necessary
+(such
+as
+entering
+a
+network
+key,
+or
+IP
+address)
+to
+use
+the
+device
+in
+a
+certain
+scenario.
+These
+actions
+can
+be
+done
+by
+anyone
+without
+specific
+training.
+</p>
+<section id="profiling-methodology">
+<div class="header-wrapper">
+<h4 id="profile-description-methodology">
+<bdi class= "secno">
+7.3.1
+</bdi>
+Profiling
+Methodology
+</h4>
+<a class="self-link" href="#profile-description-methodology" aria-label="Permalink for Section 7.3.1">
+</a>
+</div>
+<p>
+A
+profile
+is
+a
+set
+of
+constraints
+and
+rules,
+which
+provide
+additional
+semantic
+guarantees
+that
+are
+applied
+to
+the
+<a href= "#dfn-wot-thing-description" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-wot-thing-description-14">
+WoT
+Thing
+Description
+</a>
+specification.
+These
+constraints
+define
+a
+subset
+of
+valid
+<a href="#dfn-wot-thing-description" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-thing-description-15">
+WoT
+Thing
+Descriptions
+</a>
+by
+defining
+additional
+rules
+on
+various
+aspects
+of
+the
+<a href="#dfn-wot-thing-description" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-thing-description-16">
+WoT
+Thing
+Description
+</a>.
+</p>
+<table class="def">
+<tbody>
+<tr>
+<th>
+Constraints
+on
+</th>
+<th>
+Rationale
+</th>
+<th>
+Examples
+</th>
+</tr>
+<tr>
+<td>
+vocabulary
+of
+Thing
+Description
+classes
+</td>
+<td>
+guaranteed
+set
+of
+metadata
+fields
+</td>
+<td>
+Make
+specific
+vocabulary
+terms
+mandatory,
+remove
+others
+</td>
+</tr>
+<tr>
+<td>
+class
+relationships
+</td>
+<td>
+unambiguous
+structure
+</td>
+<td>
+limited
+cardinality,
+e.g.
+only
+one
+form
+per
+operation
+per
+interaction
+affordance.
+</td>
+</tr>
+<tr>
+<td>
+values
+of
+vocabulary
+terms
+</td>
+<td>
+simplified
+processing
+</td>
+<td>
+Limit
+the
+length
+of
+characters
+per
+string.
+Always
+use
+arrays,
+where
+the
+spec
+permits
+a
+string
+or
+an
+array
+of
+strings.
+</td>
+</tr>
+<tr>
+<td>
+data
+schemas
+</td>
+<td>
+simplified
+processing
+</td>
+<td>
+No
+arbitrary
+nested
+objects
+or
+arrays
+of
+arrays.
+</td>
+</tr>
+<tr>
+<td>
+security
+</td>
+<td>
+reduced
+implementation
+effort
+</td>
+<td>
+Only
+a
+restricted
+set
+of
+security
+mechanisms.
+</td>
+</tr>
+<tr>
+<td>
+protocol
+binding
+</td>
+<td>
+guaranteed
+protocol
+semantics
+</td>
+<td>
+limited
+protocol(s)
+and
+protocol
+features,
+Example:
+predefined
+mapping
+of
+http
+verbs
+(GET/PUT)
+to
+operation
+verbs,
+similar
+constraints
+for
+other
+protocols.
+</td>
+</tr>
+</tbody>
+</table>
+<p>
+These
+constraints
+and
+rules
+fall
+into
+two
+categories:
+</p>
+<ul>
+<li>
+constraints
+on
+the
+data
+model.
+</li>
+<li>
+constraints
+on
+the
+protocol
+binding.
+</li>
+</ul>
+<p>
+These
+two
+categories
+are
+orthogonal
+to
+each
+other,
+i.e.
+an
+information
+model
+that
+conforms
+to
+a
+profile
+can
+be
+mapped
+to
+different
+protocols.
+The
+protocol
+binding
+for
+each
+protocol
+may
+contain
+additional
+(protocol-specific)
+constraints.
+</p>
+<p>
+A
+profile
+is
+not
+exclusive,
+i.e.
+a
+thing
+may
+conform
+to
+multiple
+profiles.
+Profiles
+can
+build
+on
+top
+of
+each
+other
+or
+overlap,
+extended
+profiles
+can
+be
+built
+on
+top
+of
+a
+baseline
+profile.
+</p>
+<figure id="WoT-Profiles">
+<img src= "images/profiles/WoTProfiles.png" class="wot-profiles" alt= "WoT Profiles" />
+<figcaption>
+<a class="self-link" href="#WoT-Profiles">
+Figure
+<bdi class="figno">
+30
+</bdi>
+</a>
+<span class="fig-title">
+Profile
+architecture
+</span>
+</figcaption>
+</figure>
+</section>
+</section>
+<section id="sec-discovery">
+<div class="header-wrapper">
+<h3 id="x7-4-wot-discovery">
+<bdi class="secno">
+7.4
+</bdi>
+WoT
+Discovery
+</h3>
+<a class="self-link" href="#sec-discovery" aria-label= "Permalink for Section 7.4">
+</a>
+</div>
+<p>
+The
+<a href="#dfn-wot-discovery" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-discovery-6">
+WoT
+Discovery
+</a>
+specification
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href="#bib-wot-discovery" title= "Web of Things (WoT) Discovery">
+WOT-DISCOVERY
+</a>
+</cite>
+]
+defines
+mechanisms
+for
+distributing
+and
+accessing
+<a href= "#dfn-wot-thing-description" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-wot-thing-description-17">
+WoT
+Thing
+Descriptions
+</a>
+over
+the
+network.
+These
+mechanisms
+are
+meant
+to
+simplify
+access
+to
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-114">
+Things
+</a>
+and
+services
+and
+support
+their
+integration.
+<a href= "#dfn-wot-discovery" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-discovery-7">
+WoT
+Discovery
+</a>
+mechanisms
+are
+not
+limited
+by
+the
+bounds
+of
+local
+area
+networks
+and
+can
+also
+support
+remote
+discovery.
+They
+are
+also
+designed
+to
+act
+as
+extensions
+of
+existing
+search
+and
+discovery
+standards.
+</p>
+<p>
+One
+of
+the
+primary
+design
+requirements
+of
+the
+<a href= "#dfn-wot-discovery" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-discovery-8">
+WoT
+Discovery
+</a>
+building
+block
+is
+to
+protect
+the
+security
+and
+privacy
+of
+both
+consumers
+and
+providers
+of
+WoT
+data
+and
+metadata.
+In
+particular,
+<a href= "#dfn-wot-discovery" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-discovery-9">
+WoT
+Discovery
+</a>
+mechanisms
+are
+designed
+not
+only
+to
+protect
+and
+control
+access
+to
+<a href= "#dfn-wot-thing-description" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-wot-thing-description-18">
+WoT
+Thing
+Descriptions
+</a>,
+but
+also
+are
+designed
+to
+protect
+queries
+about
+such
+data
+and
+metadata,
+and
+to
+avoid
+accidental
+distribution
+of
+direct
+or
+inferrable
+metadata.
+</p>
+<p>
+In
+order
+to
+accommodate
+existing
+discovery
+technologies
+while
+providing
+strong
+privacy
+and
+security,
+<a href="#dfn-wot-discovery" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-discovery-10">
+WoT
+Discovery
+</a>
+uses
+a
+two-stage
+process.
+In
+the
+first
+stage,
+an
+"
+<a href="#dfn-wot-introduction" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-introduction-1">
+introduction
+</a>
+"
+is
+made
+using
+one
+of
+several
+first-contact
+mechanisms.
+In
+the
+second
+stage,
+called
+"
+<a href="#dfn-wot-exploration" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-exploration-1">
+exploration
+</a>
+",
+actual
+<a href= "#dfn-td" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-td-17">
+TDs
+</a>
+are
+made
+available,
+but
+only
+after
+suitable
+authentication
+and
+authorization.
+</p>
+<p>
+Two
+exploration
+mechanisms
+are
+provided,
+supporting
+both
+distribution
+of
+single
+TDs
+and
+directory
+services
+for
+multiple
+TDs:
+</p>
+<ul>
+<li>
+An
+ordinary
+web
+resource
+provided
+by
+an
+HTTP
+server
+can
+be
+used
+to
+distribute
+a
+single
+TD.
+This
+can
+also
+be
+used
+for
+self-description,
+to
+allow
+a
+Thing
+to
+provide
+its
+own
+WoT
+Thing
+Description
+directly.
+</li>
+<li>
+Directory
+services
+provide
+searchable
+databases
+of
+WoT
+Thing
+Descriptions.
+Both
+lightweight
+syntactic
+query
+mechanisms
+and
+more
+powerful
+semantic
+query
+mechanisms
+are
+supported
+by
+directory
+services.
+</li>
+</ul>
+<p>
+Use
+of
+these
+mechanisms
+is
+encouraged,
+but
+not
+mandatory.
+</p>
+<section id="sec-discovery-introductions">
+<div class="header-wrapper">
+<h4 id="x7-4-1-introduction-mechanisms">
+<bdi class= "secno">
+7.4.1
+</bdi>
+Introduction
+Mechanisms
+</h4>
+<a class="self-link" href="#sec-discovery-introductions" aria-label="Permalink for Section 7.4.1">
+</a>
+</div>
+<p>
+<a href="#dfn-wot-introduction" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-introduction-2">
+Introduction
+</a>
+mechanisms
+are
+not
+intended
+to
+provide
+strong
+security
+or
+privacy
+guarantees,
+and
+this
+allows
+a
+variety
+of
+existing
+discovery
+mechanisms
+with
+relatively
+weak
+security
+to
+be
+used,
+as
+long
+as
+they
+satisfy
+the
+following
+requirements:
+</p>
+<ul>
+<li>
+Any
+<a href="#dfn-wot-introduction" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-introduction-3">
+introduction
+</a>
+mechanism
+used
+for
+<a href="#dfn-wot-discovery" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-discovery-11">
+WoT
+Discovery
+</a>
+must
+not
+provide
+metadata
+but
+instead
+should
+simply
+result
+in
+one
+or
+more
+opaque
+URLs
+at
+which
+metadata
+may
+be
+accessed,
+if
+and
+only
+if
+the
+user
+can
+authenticate
+and
+has
+the
+appropriate
+authorization
+(access
+rights).
+</li>
+<li>
+<a href="#dfn-wot-introduction" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-introduction-4">
+Introduction
+</a>
+URLs
+must
+not
+themselves
+include
+any
+metadata,
+e.g.
+a
+human-readable
+device
+type
+or
+name.
+Randomly
+generated
+URLs
+are
+recommended.
+</li>
+</ul>
+</section>
+<section id="sec-discovery-exploration">
+<div class="header-wrapper">
+<h4 id="x7-4-2-exploration-mechanisms">
+<bdi class= "secno">
+7.4.2
+</bdi>
+Exploration
+Mechanisms
+</h4>
+<a class="self-link" href="#sec-discovery-exploration" aria-label= "Permalink for Section 7.4.2">
+</a>
+</div>
+<p>
+After
+a
+suitable
+authentication
+and
+authorization
+process
+(based
+on
+existing
+mechanisms
+to
+protect
+web
+services
+and
+existing
+protocol
+security
+negotiation
+mechanisms),
+<a href= "#dfn-wot-discovery" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-discovery-12">
+WoT
+Discovery
+</a>
+defines
+a
+set
+of
+second
+stage
+"
+<a href="#dfn-wot-exploration" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-exploration-2">
+exploration
+</a>
+"
+mechanisms
+that
+provide
+actual
+access
+to
+metadata.
+</p>
+<p>
+The
+first
+and
+simplest
+<a href="#dfn-wot-exploration" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-exploration-3">
+exploration
+</a>
+mechanism
+defines
+how
+to
+fetch
+a
+<a href="#dfn-td" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-td-18">
+TD
+</a>
+directly
+from
+the
+device
+itself.
+This
+supports
+ad-hoc
+peer-to-peer
+discovery.
+However,
+in
+many
+circumstances
+(including
+but
+not
+limited
+to
+management
+of
+large
+collections
+of
+TDs),
+an
+alternative
+<a href= "#dfn-wot-exploration" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-exploration-4">
+exploration
+</a>
+mechanism,
+the
+<a href="#dfn-wot-thing-description-directory" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-thing-description-directory-9">
+WoT
+Thing
+Description
+Directory
+</a>
+(
+<a href="#dfn-tdd" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-tdd-1">
+TDD
+</a>
+)
+service,
+is
+more
+appropriate.
+</p>
+<p>
+A
+<a href="#dfn-tdd" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-tdd-2">
+TDD
+</a>
+provides
+sophisticated
+(but
+protected)
+query
+mechanisms
+to
+explore
+and
+retrieve
+WoT
+metadata.
+<a href="#dfn-tdd" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-tdd-3">
+TDDs
+</a>
+also
+provide
+change
+notification
+mechanisms
+to
+support
+secure
+distribution
+of
+<a href="#dfn-td" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-td-19">
+TD
+</a>
+updates
+to
+authorized
+consumers.
+Any
+<a href="#dfn-wot-discovery" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-wot-discovery-13">
+WoT
+Discovery
+</a>
+"exploration"
+implementation
+must
+only
+provide
+metadata
+and
+<a href="#dfn-td" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-td-20">
+TDs
+</a>
+after
+appropriate
+best-practice
+authentication
+and
+authorization.
+Suitable
+best-practice
+security
+mechanisms
+for
+authentication
+and
+authorization
+for
+different
+circumstances
+are
+discussed
+in
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href="#bib-wot-security" title= "Web of Things (WoT) Security and Privacy Guidelines">
+WOT-SECURITY
+</a>
+</cite>
+].
+Suitable
+mechanisms
+for
+managing
+access
+controls
+and
+keys
+are
+also
+discussed
+in
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-solid" title="Solid Technical Reports">
+SOLID
+</a>
+</cite>
+].
+</p>
+<p>
+<a href="#dfn-tdd" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-tdd-4">
+TDDs
+</a>
+are
+not
+just
+a
+convenience
+feature
+but
+are
+essential
+in
+several
+WoT
+use
+cases.
+Using
+a
+<a href="#dfn-tdd" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-tdd-5">
+TDD
+</a>
+is
+appropriate
+when
+a
+<a href= "#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-115">
+Thing
+</a>
+has
+resource
+restrictions
+(e.g.,
+limited
+memory
+space,
+limited
+power),
+c.f.
+<a href= "#device-categories">
+Device
+Categories
+</a>,
+uses
+a
+specialized
+protocol
+requiring
+translation
+by
+an
+intermediary
+(in
+which
+case
+the
+<a href="#dfn-td" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-td-21">
+TD
+</a>
+provided
+by
+the
+<a href="#dfn-tdd" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-tdd-6">
+TDD
+</a>
+would
+describe
+the
+translated
+network
+interface
+supported
+by
+the
+intermediary),
+or
+when
+it
+is
+necessary
+to
+use
+an
+existing
+device
+(often
+called
+"brownfield"
+devices)
+as
+part
+of
+the
+Web
+of
+Things
+but
+the
+device
+itself
+cannot
+be
+easily
+modified
+to
+self-host
+a
+TD.
+</p>
+<p>
+<a href="#dfn-td" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-td-22">
+TDs
+</a>
+can
+be
+registered
+with
+a
+<a href= "#dfn-tdd" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-tdd-7">
+TDD
+</a>
+by
+the
+devices
+themselves
+or
+by
+an
+external
+agent.
+Use
+of
+an
+external
+agent
+will
+usually
+be
+required
+in
+the
+case
+of
+brownfield
+devices.
+</p>
+</section>
+<p>
+The
+<a href="#dfn-wot-discovery" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-discovery-14">
+Discovery
+</a>
+mechanisms
+defined
+in
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-wot-discovery" title= "Web of Things (WoT) Discovery">
+WOT-DISCOVERY
+</a>
+</cite>
+]
+are
+not
+mandatory,
+but
+they
+are
+designed
+to
+meet
+the
+above
+requirements
+and
+their
+use
+will
+enhance
+interoperability
+and
+usability.
+</p>
+</section>
+<section id="sec-binding-templates">
+<div class="header-wrapper">
+<h3 id="x7-5-wot-binding-templates">
+<bdi class="secno">
+7.5
+</bdi>
+WoT
+Binding
+Templates
+</h3>
+<a class="self-link" href="#sec-binding-templates" aria-label= "Permalink for Section 7.5">
+</a>
+</div>
+<p>
+The
+IoT
+uses
+a
+variety
+of
+protocols
+for
+accessing
+devices,
+since
+no
+single
+protocol
+is
+appropriate
+in
+all
+contexts.
+Thus,
+a
+central
+challenge
+for
+the
+Web
+of
+Things
+is
+to
+enable
+interactions
+with
+the
+plethora
+of
+different
+<a href="#dfn-iot-platform" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-iot-platform-3">
+IoT
+platforms
+</a>
+(e.g.,
+OMA
+LWM2M,
+OPC
+UA,
+oneM2M)
+and
+devices
+that
+do
+not
+follow
+any
+particular
+standard,
+but
+provide
+an
+eligible
+interface
+over
+a
+suitable
+network
+protocol.
+WoT
+is
+tackling
+this
+variety
+through
+<a href= "#dfn-wot-protocol-binding" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-wot-protocol-binding-10">
+Protocol
+Bindings
+</a>,
+which
+must
+meet
+a
+number
+of
+constraints
+(see
+<a href= "#sec-protocol-bindings" class="sec-ref">
+<bdi class= "secno">
+6.7
+</bdi>
+Protocol
+Bindings
+</a>
+).
+</p>
+<p>
+The
+<a href="#dfn-wot-binding-templates" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-binding-templates-2">
+Binding
+Templates
+</a>
+address
+the
+aspect
+that
+an
+application
+client
+(a
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-53">
+Consumer
+</a>
+)
+can
+use
+the
+<a href= "#dfn-thing-description" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-description-29">
+Thing
+Description
+</a>
+to
+extract
+the
+specific
+metadata
+of
+the
+protocols
+(e.g.
+about
+HTTP,
+MQTT,
+Modbus,
+etc.),
+payload
+formats
+(binary,
+JSON,
+CBOR,
+EXI,
+etc.)
+and
+their
+usage
+in
+an
+IoT
+platform
+context
+(e.g.,
+ECHONET,
+OPC
+UA).
+The
+metadata
+can
+be
+passed
+to
+a
+network
+implementation
+interface
+to
+establish
+interaction
+with
+the
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-116">
+Thing
+</a>
+and
+to
+serialize
+/
+deserialize
+the
+payload
+messages.
+In
+that
+context,
+<a href= "#dfn-wot-binding-templates" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-wot-binding-templates-3">
+Binding
+Templates
+</a>
+include
+three
+kinds
+of
+bindings:
+Protocol
+bindings,
+Payload
+format
+bindings,
+and
+Platform
+bindings.
+</p>
+<p>
+The
+non-normative
+<a href="#dfn-wot-binding-templates" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-binding-templates-4">
+WoT
+Binding
+Templates
+</a>
+specification
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href="#bib-wot-binding-templates" title= "Web of Things (WoT) Binding Templates">
+WOT-BINDING-TEMPLATES
+</a>
+</cite>
+]
+provides
+a
+collection
+of
+blueprints
+that
+give
+guidance
+on
+how
+to
+interact
+with
+different
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-117">
+Things
+</a>
+that
+use
+different
+<a href="#dfn-transport-protocol" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-transport-protocol-2">
+transport
+protocols
+</a>,
+<a href="#dfn-content-type" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-content-type-1">
+content
+types
+</a>
+or
+that
+are
+different
+<a href="#dfn-iot-platform" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-iot-platform-4">
+IoT
+platforms
+</a>
+or
+standards
+(e.g.,
+OCF,
+oneM2M,
+OMA
+LWM2M,
+OPC
+UA)
+which
+use
+certain
+combinations
+of
+<a href="#dfn-transport-protocol" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-transport-protocol-3">
+transport
+protocols
+</a>
+and
+<a href="#dfn-content-type" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-content-type-2">
+content
+types
+</a>.
+When
+describing
+a
+particular
+IoT
+device
+or
+platform,
+the
+corresponding
+<a href="#dfn-wot-binding-templates" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-binding-templates-5">
+Binding
+Template
+</a>
+can
+be
+used
+to
+look
+up
+the
+communication
+metadata
+that
+is
+to
+be
+provided
+in
+the
+<a href="#dfn-thing-description" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-description-30">
+Thing
+Description
+</a>
+to
+support
+that
+platform.
+</p>
+<figure id="fig-binding-templates">
+<img src= "images/bblocks/binding-templates.png" srcset= "images/bblocks/binding-templates.svg" class="wot-arch-diagram" alt="binding templates" />
+<figcaption>
+<a class="self-link" href= "#fig-binding-templates">
+Figure
+<bdi class="figno">
+31
+</bdi>
+</a>
+<span class="fig-title">
+From
+Binding
+Templates
+to
+Protocol
+Bindings
+</span>
+</figcaption>
+</figure>
+<p>
+<a href="#fig-binding-templates" class="fig-ref" title= "From Binding Templates to Protocol Bindings">
+Figure
+<bdi class= "">
+31
+</bdi>
+</a>
+shows
+how
+<a href="#dfn-wot-binding-templates" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-binding-templates-6">
+Binding
+Templates
+</a>
+are
+used.
+Based
+on
+the
+protocol,
+media
+type
+or
+platform
+binding,
+a
+<a href="#dfn-td" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-td-23">
+TD
+</a>
+is
+created.
+The
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-54">
+Consumer
+</a>
+that
+is
+processing
+a
+<a href="#dfn-td" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-td-24">
+TD
+</a>
+implements
+the
+required
+<a href= "#dfn-wot-binding-templates" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-wot-binding-templates-7">
+Binding
+Template
+</a>
+that
+is
+present
+in
+the
+TD
+by
+including
+a
+corresponding
+protocol
+stack,
+media
+type
+encoder/decoder
+or
+platform
+stack
+and
+by
+configuring
+the
+stack
+(or
+its
+messages)
+according
+to
+the
+information
+given
+in
+the
+<a href="#dfn-td" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-td-25">
+TD
+</a>
+such
+as
+serialization
+format
+of
+the
+messages
+and
+header
+options.
+</p>
+<p>
+The
+<a href="#dfn-wot-binding-templates" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-binding-templates-8">
+Binding
+Templates
+</a>
+spans
+three
+dimensions:
+</p>
+<ul>
+<li>
+<b>
+Protocol
+</b>
+<p>
+The
+Web
+of
+Things
+uses
+the
+term
+<a href= "#dfn-transport-protocol" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-transport-protocol-4">
+transport
+protocol
+</a>
+for
+the
+underlying,
+standardized
+application-layer
+protocol
+without
+application-specific
+options
+or
+<a href="#dfn-subprotocol" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-subprotocol-1">
+subprotocol
+</a>
+mechanisms.
+The
+URI
+scheme
+found
+in
+the
+form
+of
+an
+<a href= "#dfn-interaction-affordance" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-interaction-affordance-25">
+Interaction
+Affordance
+</a>
+and
+the
+associated
+protocol
+endpoint
+URI
+contains
+the
+information
+required
+to
+identify
+the
+<a href= "#dfn-transport-protocol" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-transport-protocol-5">
+transport
+protocol
+</a>,
+e.g.,
+HTTP,
+CoAPS,
+or
+WebSocket
+through
+<code>
+http
+</code>,
+<code>
+coaps
+</code>,
+or
+<code>
+ws
+</code>,
+respectively.
+</p>
+<ul>
+<li>
+<b>
+Subprotocol
+</b>
+<p>
+<a href="#dfn-transport-protocol" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-transport-protocol-6">
+Transport
+protocols
+</a>
+may
+have
+to
+use
+information
+provided
+by
+an
+extension
+mechanisms
+to
+interact
+successfully.
+Such
+<a href="#dfn-subprotocol" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-subprotocol-2">
+subprotocols
+</a>
+cannot
+be
+identified
+from
+the
+URI
+scheme
+alone
+and
+must
+be
+declared
+explicitly
+using
+the
+<code>
+subprotocol
+</code>
+field
+inside
+forms.
+Examples
+for
+HTTP
+are
+long
+polling
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-rfc6202" title= "Known Issues and Best Practices for the Use of Long Polling and Streaming in Bidirectional HTTP">
+RFC6202
+</a>
+</cite>
+]
+(
+<code>
+longpoll
+</code>
+)
+or
+Server-Sent
+Events
+[
+<cite>
+<a class= "bibref" data-link-type="biblio" href="#bib-html" title= "HTML Standard">
+HTML
+</a>
+</cite>
+]
+(
+<code>
+sse
+</code>
+).
+</p>
+</li>
+</ul>
+</li>
+<li>
+<b>
+Payload
+Representation
+</b>
+<p>
+Representation
+formats
+(a.k.a.
+serializations)
+used
+for
+exchanging
+data
+can
+differ
+between
+protocols,
+<a href= "#dfn-iot-platform" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-iot-platform-5">
+IoT
+Platforms
+</a>
+and
+standards.
+The
+media
+type
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-rfc2046" title= "Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types">
+RFC2046
+</a>
+</cite>
+]
+identifies
+these
+formats,
+while
+media
+type
+parameters
+may
+specify
+them
+further.
+Forms
+may
+contain
+the
+media
+type
+and
+optional
+parameters
+in
+additional
+form
+fields
+such
+as
+a
+content
+type
+field
+known
+from
+HTTP,
+which
+combines
+media
+type
+and
+its
+potential
+parameters
+(e.g.,
+<code>
+text/plain;
+charset=utf-8
+</code>
+).
+</p>
+</li>
+<li>
+<b>
+Platforms
+and
+Standards
+</b>
+<p>
+<a href="#dfn-iot-platform" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-iot-platform-6">
+IoT
+Platforms
+</a>
+and
+standards
+often
+introduce
+specific
+modifications
+at
+the
+application
+layer
+such
+as
+platform-specific
+HTTP
+header
+fields
+or
+CoAP
+options.
+They
+can
+also
+contain
+specific
+payload
+structures
+on
+top
+of
+the
+media
+types
+that
+need
+to
+be
+accurately
+incorporated
+into
+each
+message
+between
+the
+Thing
+and
+its
+Consumer.
+Both
+the
+protocol
+modification
+and
+payload
+representation
+specific
+to
+different
+platforms
+can
+be
+represented
+in
+<a href="#dfn-td" class= "internalDFN" data-link-type="dfn" id="ref-for-dfn-td-26">
+TDs
+</a>
+using
+the
+best
+practices
+documented
+in
+binding
+templates
+for
+platforms
+and
+standards.
+</p>
+</li>
+</ul>
+</section>
+<section id="sec-scripting-api">
+<div class="header-wrapper">
+<h3 id="x7-6-wot-scripting-api">
+<bdi class="secno">
+7.6
+</bdi>
+WoT
+Scripting
+API
+</h3>
+<a class="self-link" href="#sec-scripting-api" aria-label= "Permalink for Section 7.6">
+</a>
+</div>
+<p>
+The
+<a href="#dfn-wot-scripting-api" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-scripting-api-3">
+WoT
+Scripting
+API
+</a>
+is
+an
+optional
+"convenience"
+building
+block
+of
+<abbr title="World Wide Web Consortium">
+W3C
+</abbr>
+WoT
+that
+eases
+IoT
+application
+development
+by
+providing
+an
+ECMAScript-based
+API
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-ecmascript" title= "ECMAScript Language Specification">
+ECMAScript
+</a>
+</cite>
+]
+similar
+to
+the
+Web
+browser
+APIs.
+By
+integrating
+a
+scripting
+runtime
+system
+into
+the
+<a href="#dfn-wot-runtime" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-runtime-1">
+WoT
+Runtime
+</a>,
+the
+<a href="#dfn-wot-scripting-api" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-scripting-api-4">
+WoT
+Scripting
+API
+</a>
+enables
+using
+portable
+application
+scripts
+that
+define
+the
+behavior
+of
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-118">
+Things
+</a>,
+<a href="#dfn-consumer" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-55">
+Consumers
+</a>,
+and
+<a href= "#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-31">
+Intermediaries
+</a>.
+</p>
+<p>
+Traditionally,
+IoT
+device
+logic
+is
+implemented
+in
+firmware,
+which
+results
+in
+productivity
+constraints
+similar
+to
+that
+of
+embedded
+development,
+including
+a
+relatively
+complex
+update
+process.
+The
+<a href="#dfn-wot-scripting-api" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-scripting-api-5">
+WoT
+Scripting
+API
+</a>
+in
+contrast
+enables
+implementing
+device
+logic
+by
+reusable
+scripts
+executed
+in
+a
+runtime
+system
+for
+IoT
+applications.
+It
+is
+similar
+to
+that
+of
+a
+Web
+browser,
+and
+aims
+to
+improve
+productivity
+and
+reduce
+integration
+costs.
+Furthermore,
+standardized
+APIs
+enable
+portability
+for
+application
+modules,
+for
+instance,
+to
+move
+compute-intense
+logic
+from
+a
+device
+up
+to
+a
+local
+gateway,
+or
+to
+move
+time-critical
+logic
+from
+the
+cloud
+down
+to
+a
+gateway
+or
+edge
+node.
+</p>
+<p>
+The
+non-normative
+<a href="#dfn-wot-scripting-api" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-scripting-api-6">
+WoT
+Scripting
+API
+</a>
+specification
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href="#bib-wot-scripting-api" title= "Web of Things (WoT) Scripting API">
+WOT-SCRIPTING-API
+</a>
+</cite>
+]
+defines
+the
+structure
+and
+algorithms
+of
+the
+programming
+interface
+that
+allows
+scripts
+to
+discover,
+consume,
+and
+expose
+<a href= "#dfn-wot-thing-description" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-wot-thing-description-19">
+WoT
+Thing
+Descriptions
+</a>.
+The
+runtime
+system
+of
+the
+<a href= "#dfn-wot-scripting-api" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-scripting-api-7">
+WoT
+Scripting
+API
+</a>
+instantiates
+local
+objects
+that
+act
+as
+an
+interface
+to
+other
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-119">
+Things
+</a>
+and
+their
+<a href= "#dfn-interaction-affordance" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-interaction-affordance-26">
+Interaction
+Affordances
+</a>
+(
+<a href="#dfn-property" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-property-8">
+Properties
+</a>,
+<a href="#dfn-action" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-action-7">
+Actions
+</a>,
+and
+<a href="#dfn-event" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-event-8">
+Events
+</a>
+).
+It
+also
+allows
+scripts
+to
+expose
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-120">
+Things
+</a>,
+that
+is,
+to
+define
+and
+implement
+<a href="#dfn-interaction-affordance" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-interaction-affordance-27">
+Interaction
+Affordances
+</a>
+and
+publish
+a
+<a href="#dfn-thing-description" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-description-31">
+Thing
+Description
+</a>.
+</p>
+</section>
+<section id="sec-security-guidelines">
+<div class="header-wrapper">
+<h3 id="x7-7-wot-security-and-privacy-guidelines">
+<bdi class= "secno">
+7.7
+</bdi>
+WoT
+Security
+and
+Privacy
+Guidelines
+</h3>
+<a class="self-link" href="#sec-security-guidelines" aria-label= "Permalink for Section 7.7">
+</a>
+</div>
+<p>
+Security
+is
+a
+cross-cutting
+concern
+and
+should
+be
+considered
+in
+all
+aspects
+of
+system
+design.
+In
+the
+WoT
+architecture,
+security
+is
+supported
+by
+certain
+explicit
+features,
+such
+as
+support
+for
+<a href="#dfn-public-security-metadata" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-public-security-metadata-3">
+Public
+Security
+Metadata
+</a>
+in
+<a href="#dfn-td" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-td-27">
+TDs
+</a>
+and
+by
+separation
+of
+concerns
+in
+the
+design
+of
+the
+<a href= "#dfn-wot-scripting-api" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-scripting-api-8">
+WoT
+Scripting
+API
+</a>.
+The
+specification
+for
+each
+building
+block
+also
+includes
+a
+discussion
+of
+particular
+security
+and
+privacy
+considerations
+of
+that
+building
+block.
+Another
+non-normative
+specification,
+the
+<em>
+WoT
+Security
+and
+Privacy
+Guidelines
+</em>
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href="#bib-wot-security" title= "Web of Things (WoT) Security and Privacy Guidelines">
+WOT-SECURITY
+</a>
+</cite>
+],
+provides
+additional
+cross-cutting
+security
+and
+privacy
+guidance.
+</p>
+</section>
+</section>
+<section id="sec-servient-implementation" class="informative">
+<div class="header-wrapper">
+<h2 id="x8-abstract-servient-architecture">
+<bdi class= "secno">
+8.
+</bdi>
+Abstract
+Servient
+Architecture
+</h2>
+<a class="self-link" href="#sec-servient-implementation" aria-label="Permalink for Section 8.">
+</a>
+</div>
+<p>
+<em>
+This
+section
+is
+non-normative.
+</em>
+</p>
+<p>
+As
+defined
+in
+<a href= "#sec-wot-servient-architecture-high-level" class= "sec-ref">
+<bdi class="secno">
+6.10
+</bdi>
+WoT
+System
+Components
+and
+their
+Interconnectivity
+</a>,
+a
+<a href="#dfn-servient" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-servient-15">
+Servient
+</a>
+is
+a
+software
+stack
+that
+implements
+the
+WoT
+building
+blocks
+presented
+in
+the
+previous
+section.
+<a href="#dfn-servient" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-servient-16">
+Servients
+</a>
+can
+host
+and
+expose
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-121">
+Things
+</a>
+and/or
+consume
+<a href="#dfn-thing" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-thing-122">
+Things
+</a>
+(i.e.,
+host
+<a href= "#dfn-consumer" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-56">
+Consumers
+</a>
+).
+Depending
+on
+the
+<a href= "#dfn-wot-protocol-binding" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-wot-protocol-binding-11">
+Protocol
+Binding
+</a>,
+<a href="#dfn-servient" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-servient-17">
+Servients
+</a>
+can
+perform
+in
+both
+server
+and
+client
+role,
+hence
+the
+portmanteau
+naming.
+</p>
+<p>
+The
+previous
+section
+describes
+how
+the
+WoT
+building
+blocks
+conceptually
+relate
+to
+each
+other
+and
+how
+they
+correspond
+to
+the
+abstract
+WoT
+Architecture
+(see
+<a href="#sec-wot-architecture" class="sec-ref">
+<bdi class="secno">
+6.
+</bdi>
+Abstract
+WoT
+System
+Architecture
+</a>
+).
+When
+implementing
+these
+concepts,
+a
+more
+detailed
+view
+is
+necessary
+that
+takes
+certain
+technical
+aspects
+into
+account.
+This
+section
+describes
+the
+detailed
+architecture
+of
+a
+<a href="#dfn-servient" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-servient-18">
+Servient
+</a>
+implementation.
+</p>
+<p>
+<a href="#architecture-implementation" class="fig-ref" title= "Implementation of a Servient using the WoT Scripting API">
+Figure
+<bdi class="">
+32
+</bdi>
+</a>
+shows
+a
+<a href="#dfn-servient" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-servient-19">
+Servient
+</a>
+implementation
+that
+is
+using
+the
+(optional)
+<a href="#dfn-wot-scripting-api" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-scripting-api-9">
+WoT
+Scripting
+API
+</a>
+building
+block.
+Here,
+the
+<a href= "#dfn-wot-runtime" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-runtime-2">
+WoT
+Runtime
+</a>
+is
+also
+a
+Scripting
+Runtime
+system
+that,
+in
+addition
+to
+managing
+the
+WoT-specific
+aspects,
+also
+interprets
+and
+executes
+the
+application
+scripts.
+<a href="#dfn-servient" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-servient-20">
+Servients
+</a>
+that
+support
+the
+<a href="#dfn-wot-scripting-api" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-scripting-api-10">
+WoT
+Scripting
+API
+</a>
+usually
+run
+on
+powerful
+devices,
+edge
+nodes,
+or
+in
+the
+cloud
+(c.f.
+<a href="#device-categories">
+Device
+Categories
+</a>
+).
+The
+WoT
+Architecture
+does
+not
+limit
+the
+application-facing
+API
+of
+the
+<a href="#dfn-wot-runtime" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-runtime-3">
+WoT
+Runtime
+</a>
+to
+JavaScript/ECMAScript.
+Also
+other
+runtime
+systems
+can
+be
+used
+to
+implement
+a
+<a href="#dfn-servient" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-servient-21">
+Servient
+</a>.
+</p>
+<p>
+Section
+<a href="#native-impl" class="sec-ref">
+<bdi class= "secno">
+8.8.1
+</bdi>
+Native
+WoT
+API
+</a>
+presents
+an
+alternative
+<a href="#dfn-servient" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-servient-22">
+Servient
+</a>
+implementation
+without
+the
+<a href="#dfn-wot-scripting-api" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-scripting-api-11">
+WoT
+Scripting
+API
+</a>
+building
+block.
+The
+<a href="#dfn-wot-runtime" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-runtime-4">
+WoT
+Runtime
+</a>
+may
+use
+any
+programming
+language
+for
+its
+application-facing
+API.
+Usually,
+it
+is
+the
+native
+language
+of
+the
+<a href="#dfn-servient" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-servient-23">
+Servient
+</a>
+software
+stack,
+for
+instance
+C/C++
+for
+embedded
+<a href= "#dfn-servient" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-servient-24">
+Servients
+</a>
+or
+Java
+for
+cloud-based
+<a href="#dfn-servient" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-servient-25">
+Servients
+</a>.
+It
+may
+also
+be
+an
+alternative
+scripting
+language
+such
+as
+Lua
+to
+combine
+the
+benefits
+of
+application
+scripts
+with
+low
+resource
+consumption.
+</p>
+<figure id="architecture-implementation">
+<img src= "images/servient/wot-thing-scripting.png" srcset= "images/servient/wot-thing-scripting.svg" class="wot-arch-diagram" alt="architecture implementation" />
+<figcaption>
+<a class="self-link" href= "#architecture-implementation">
+Figure
+<bdi class= "figno">
+32
+</bdi>
+</a>
+<span class="fig-title">
+Implementation
+of
+a
+Servient
+using
+the
+WoT
+Scripting
+API
+</span>
+</figcaption>
+</figure>
+<p>
+The
+role
+and
+functionality
+of
+each
+module
+shown
+in
+<a href= "#architecture-implementation" class="fig-ref" title= "Implementation of a Servient using the WoT Scripting API">
+Figure
+<bdi class="">
+32
+</bdi>
+</a>
+is
+explained
+in
+the
+following
+sections.
+</p>
+<section id="behavior-implementation">
+<div class="header-wrapper">
+<h3 id="x8-1-behavior-implementation">
+<bdi class="secno">
+8.1
+</bdi>
+Behavior
+Implementation
+</h3>
+<a class="self-link" href="#behavior-implementation" aria-label= "Permalink for Section 8.1">
+</a>
+</div>
+<p>
+The
+<em>
+behavior
+</em>
+defines
+the
+overall
+application
+logic
+of
+a
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-123">
+Thing
+</a>,
+which
+has
+several
+aspects:
+</p>
+<p>
+It
+includes
+<em>
+autonomous
+behavior
+</em>
+of
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-124">
+Things
+</a>
+(e.g.,
+sampling
+of
+sensors
+or
+control
+loops
+for
+actuators),
+the
+<em>
+handlers
+</em>
+for
+<a href= "#dfn-interaction-affordance" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-interaction-affordance-28">
+Interaction
+Affordances
+</a>
+(i.e.,
+the
+concrete
+actions
+taken
+when
+an
+affordance
+is
+activated),
+<em>
+<a href="#dfn-consumer" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-57">
+Consumer
+</a>
+behavior
+</em>
+(e.g.,
+controlling
+a
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-125">
+Thing
+</a>
+or
+realizing
+mashups),
+and
+<em>
+<a href="#dfn-intermediary" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-32">
+Intermediary
+</a>
+behavior
+</em>
+(e.g.,
+simply
+proxying
+a
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-126">
+Thing
+</a>
+or
+composing
+virtual
+entities).
+The
+behavior
+implementation
+within
+a
+<a href="#dfn-servient" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-servient-26">
+Servient
+</a>
+defines
+which
+<a href= "#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-127">
+Things
+</a>,
+<a href="#dfn-consumer" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-58">
+Consumers
+</a>,
+and
+<a href= "#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-33">
+Intermediaries
+</a>
+are
+hosted
+on
+this
+component.
+</p>
+<p>
+<a href="#architecture-implementation" class="fig-ref" title= "Implementation of a Servient using the WoT Scripting API">
+Figure
+<bdi class="">
+32
+</bdi>
+</a>
+depicts
+<a href="#dfn-servient" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-servient-27">
+Servients
+</a>
+that
+are
+implementing
+the
+optional
+<a href="#dfn-wot-scripting-api" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-scripting-api-12">
+WoT
+Scripting
+API
+</a>
+building
+block,
+where
+portable
+application
+scripts
+written
+in
+JavaScript
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href="#bib-ecmascript" title= "ECMAScript Language Specification">
+ECMAScript
+</a>
+</cite>
+]
+define
+the
+behavior.
+They
+are
+executed
+by
+a
+scripting
+runtime
+system
+that
+is
+part
+of
+the
+<a href="#dfn-wot-runtime" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-runtime-5">
+WoT
+Runtime
+</a>
+(when
+providing
+the
+<a href="#dfn-wot-scripting-api" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-scripting-api-13">
+WoT
+Scripting
+API
+</a>
+or
+any
+other
+script-based
+API).
+They
+are
+portable,
+as
+they
+are
+written
+against
+the
+common
+<a href="#dfn-wot-scripting-api" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-scripting-api-14">
+WoT
+Scripting
+API
+</a>
+definitions,
+and
+hence
+can
+be
+executed
+by
+any
+<a href= "#dfn-servient" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-servient-28">
+Servient
+</a>
+featuring
+this
+building
+block.
+This
+makes
+it
+possible
+to
+shift
+application
+logic
+between
+system
+components,
+for
+instance
+moving
+a
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-59">
+Consumer
+</a>
+from
+the
+cloud
+to
+an
+edge
+node
+to
+meet
+networking
+requirements,
+or
+to
+move
+an
+<a href= "#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-34">
+Intermediary
+</a>
+to
+the
+cloud
+to
+fulfill
+growing
+resource
+demands.
+Portable
+applications
+enable
+to
+'install'
+additional
+behavior
+after
+the
+deployment
+of
+a
+Servient.
+</p>
+<p>
+In
+principle,
+any
+programming
+language
+and
+API
+can
+be
+used
+in
+order
+to
+define
+the
+behavior
+of
+a
+Thing,
+as
+long
+as
+the
+<a href= "#dfn-interaction-affordance" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-interaction-affordance-29">
+Interaction
+Affordances
+</a>
+are
+presented
+externally
+through
+a
+<a href= "#dfn-wot-interface" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-interface-7">
+WoT
+Interface
+</a>.
+The
+adaption
+between
+application-facing
+API
+and
+the
+protocol
+stack
+is
+handled
+by
+the
+<a href="#dfn-wot-runtime" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-wot-runtime-6">
+WoT
+Runtime
+</a>.
+See
+<a href= "#native-impl" class="sec-ref">
+<bdi class="secno">
+8.8.1
+</bdi>
+Native
+WoT
+API
+</a>
+for
+behavior
+implementation
+without
+the
+<a href= "#dfn-wot-scripting-api" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-scripting-api-15">
+WoT
+Scripting
+API
+</a>
+building
+block.
+</p>
+</section>
+<section id="wot-runtime">
+<div class="header-wrapper">
+<h3 id="x8-2-wot-runtime">
+<bdi class="secno">
+8.2
+</bdi>
+WoT
+Runtime
+</h3>
+<a class="self-link" href="#wot-runtime" aria-label= "Permalink for Section 8.2">
+</a>
+</div>
+<p>
+Technically,
+the
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-128">
+Thing
+</a>
+abstraction
+and
+its
+<a href="#dfn-interaction-model" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-interaction-model-3">
+Interaction
+Model
+</a>
+is
+implemented
+in
+a
+runtime
+system.
+This
+<a href="#dfn-wot-runtime" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-runtime-7">
+WoT
+Runtime
+</a>
+maintains
+the
+execution
+environment
+for
+the
+behavior
+implementation
+and
+is
+able
+to
+expose
+and/or
+consume
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-129">
+Things
+</a>,
+and
+hence
+must
+be
+able
+to
+fetch,
+process,
+serialize,
+and
+serve
+<a href= "#dfn-wot-thing-description" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-wot-thing-description-20">
+WoT
+Thing
+Descriptions
+</a>.
+</p>
+<p>
+Every
+<a href="#dfn-wot-runtime" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-runtime-8">
+WoT
+Runtime
+</a>
+has
+an
+application-facing
+interface
+(i.e.,
+an
+API)
+for
+the
+behavior
+implementation.
+The
+optional
+<a href="#dfn-wot-scripting-api" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-scripting-api-16">
+WoT
+Scripting
+API
+</a>
+building
+block
+shown
+in
+<a href="#architecture-implementation" class= "fig-ref" title= "Implementation of a Servient using the WoT Scripting API">
+Figure
+<bdi class="">
+32
+</bdi>
+</a>
+defines
+such
+an
+application-facing
+interface
+that
+follows
+the
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-130">
+Thing
+</a>
+abstraction
+and
+enables
+the
+deployment
+of
+behavior
+implementations
+during
+runtime
+through
+application
+scripts.
+See
+<a href= "#native-impl" class="sec-ref">
+<bdi class="secno">
+8.8.1
+</bdi>
+Native
+WoT
+API
+</a>
+for
+alternative
+APIs,
+which
+can
+also
+only
+be
+available
+during
+compile
+time.
+In
+general,
+application
+logic
+should
+be
+executed
+in
+sandboxed
+execution
+environments
+that
+prevent
+unauthorized
+access
+to
+the
+management
+aspects
+of
+the
+<a href= "#dfn-wot-runtime" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-runtime-9">
+WoT
+Runtime
+</a>
+from
+the
+application
+code,
+in
+particular
+the
+<a href="#dfn-private-security-data" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-private-security-data-2">
+Private
+Security
+Data
+</a>.
+In
+multi-tenant
+<a href="#dfn-servient" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-servient-29">
+Servients
+</a>,
+different
+tenants
+should
+also
+be
+prevented
+from
+accessing
+each
+other's
+data
+without
+authorization.
+</p>
+<p>
+A
+<a href="#dfn-wot-runtime" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-wot-runtime-10">
+WoT
+Runtime
+</a>
+needs
+to
+provide
+certain
+operations
+to
+manage
+the
+lifecycle
+of
+<a href= "#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-131">
+Things
+</a>,
+or
+more
+precisely
+their
+software
+abstractions
+and
+descriptions.
+A
+lifecycle
+management
+(LCM)
+system
+may
+encapsulate
+those
+lifecycle
+operations
+within
+a
+<a href="#dfn-servient" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-servient-30">
+Servient
+</a>
+and
+use
+internal
+interfaces
+to
+realize
+the
+lifecycle
+management.
+The
+details
+of
+such
+operations
+vary
+among
+different
+implementations.
+The
+<a href= "#dfn-wot-scripting-api" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-scripting-api-17">
+WoT
+Scripting
+API
+</a>
+includes
+LCM
+functionality,
+and
+hence
+represents
+one
+possible
+implementation
+of
+such
+a
+system.
+</p>
+<p>
+The
+<a href="#dfn-wot-runtime" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-runtime-11">
+WoT
+Runtime
+</a>
+must
+interface
+with
+the
+protocol
+stack
+implementation
+of
+the
+<a href="#dfn-servient" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-servient-31">
+Servient
+</a>,
+as
+it
+decouples
+the
+behavior
+implementation
+from
+the
+details
+of
+the
+<a href= "#dfn-wot-protocol-binding" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-wot-protocol-binding-12">
+Protocol
+Bindings
+</a>.
+The
+<a href="#dfn-wot-runtime" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-runtime-12">
+WoT
+Runtime
+</a>
+usually
+also
+interfaces
+with
+the
+underlying
+system,
+for
+instance,
+to
+access
+local
+hardware
+such
+as
+attached
+sensors
+and
+actuators
+or
+to
+access
+system
+services
+such
+as
+storage.
+Both
+interfaces
+are
+implementation-specific,
+yet
+the
+<a href= "#dfn-wot-runtime" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-runtime-13">
+WoT
+Runtime
+</a>
+must
+provide
+the
+necessary
+adaption
+to
+the
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-132">
+Thing
+</a>
+abstraction
+it
+implements.
+</p>
+</section>
+<section id="wot-scripting-api">
+<div class="header-wrapper">
+<h3 id="x8-3-wot-scripting-api">
+<bdi class="secno">
+8.3
+</bdi>
+WoT
+Scripting
+API
+</h3>
+<a class="self-link" href="#wot-scripting-api" aria-label= "Permalink for Section 8.3">
+</a>
+</div>
+<p>
+The
+<a href="#dfn-wot-scripting-api" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-scripting-api-18">
+WoT
+Scripting
+API
+</a>
+building
+block
+defines
+an
+ECMAScript
+API
+that
+closely
+follows
+the
+<a href="#dfn-wot-thing-description" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-thing-description-21">
+WoT
+Thing
+Description
+</a>
+specification
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href="#bib-wot-thing-description" title= "Web of Things (WoT) Thing Description 1.1">
+WOT-THING-DESCRIPTION
+</a>
+</cite>
+].
+It
+defines
+the
+interface
+between
+behavior
+implementations
+and
+a
+scripting-based
+<a href="#dfn-wot-runtime" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-runtime-14">
+WoT
+Runtime
+</a>.
+Other,
+simpler
+APIs
+may
+be
+implemented
+on
+top
+of
+it,
+similar
+to,
+for
+instance,
+jQuery
+for
+the
+Web
+browser
+APIs.
+</p>
+<p>
+See
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-wot-scripting-api" title= "Web of Things (WoT) Scripting API">
+WOT-SCRIPTING-API
+</a>
+</cite>
+]
+for
+more
+details.
+</p>
+</section>
+<section id="expose-consumed-thing">
+<div class="header-wrapper">
+<h3 id="x8-4-exposed-thing-and-consumed-thing-abstractions">
+<bdi class="secno">
+8.4
+</bdi>
+Exposed
+Thing
+and
+Consumed
+Thing
+Abstractions
+</h3>
+<a class="self-link" href="#expose-consumed-thing" aria-label= "Permalink for Section 8.4">
+</a>
+</div>
+<p>
+The
+<a href="#dfn-wot-runtime" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-runtime-15">
+WoT
+Runtime
+</a>
+instantiates
+software
+representations
+of
+<a href= "#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-133">
+Things
+</a>
+based
+on
+their
+<a href="#dfn-td" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-td-28">
+TDs
+</a>.
+These
+software
+representations
+provide
+the
+interface
+towards
+the
+behavior
+implementation.
+</p>
+<p>
+The
+<a href="#dfn-exposed-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-exposed-thing-12">
+Exposed
+Thing
+</a>
+abstraction
+represents
+a
+<a href="#dfn-thing" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-134">
+Thing
+</a>
+hosted
+locally
+and
+accessible
+from
+the
+outside
+through
+the
+protocol
+stack
+implementation
+of
+the
+<a href="#dfn-servient" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-servient-32">
+Servient
+</a>.
+The
+behavior
+implementation
+can
+fully
+control
+<a href="#dfn-exposed-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-exposed-thing-13">
+Exposed
+Things
+</a>
+by
+defining
+their
+metadata
+and
+<a href="#dfn-interaction-affordance" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-interaction-affordance-30">
+Interaction
+Affordances
+</a>,
+and
+providing
+their
+autonomous
+behavior.
+</p>
+<p>
+The
+<a href="#dfn-consumed-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-consumed-thing-11">
+Consumed
+Thing
+</a>
+abstraction
+represents
+a
+remotely
+hosted
+<a href= "#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-135">
+Thing
+</a>
+for
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-60">
+Consumers
+</a>
+that
+needs
+to
+be
+accessed
+using
+a
+communication
+protocol.
+<a href="#dfn-consumed-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumed-thing-12">
+Consumed
+Things
+</a>
+are
+proxy
+objects
+or
+stubs.
+The
+behavior
+implementation
+is
+restricted
+to
+reading
+their
+metadata
+and
+activating
+their
+<a href= "#dfn-interaction-affordance" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-interaction-affordance-31">
+Interaction
+Affordances
+</a>
+as
+described
+in
+the
+corresponding
+<a href="#dfn-td" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-td-29">
+TD
+</a>.
+<a href="#dfn-consumed-thing" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumed-thing-13">
+Consumed
+Things
+</a>
+can
+also
+represent
+system
+features
+such
+as
+local
+hardware
+or
+devices
+behind
+proprietary
+or
+legacy
+communication
+protocols.
+In
+this
+case,
+the
+<a href="#dfn-wot-runtime" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-runtime-16">
+WoT
+Runtime
+</a>
+must
+provide
+the
+necessary
+adaptation
+between
+system
+API
+and
+<a href= "#dfn-consumed-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumed-thing-14">
+Consumed
+Thing
+</a>.
+Furthermore,
+it
+must
+provide
+corresponding
+<a href="#dfn-td" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-td-30">
+TDs
+</a>
+and
+make
+them
+available
+to
+the
+behavior
+implementation,
+for
+instance,
+by
+extending
+whatever
+discovery
+mechanism
+is
+provided
+by
+the
+<a href= "#dfn-wot-runtime" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-runtime-17">
+WoT
+Runtime
+</a>
+through
+the
+application-facing
+API
+(e.g.,
+the
+<code>
+discover()
+</code>
+method
+defined
+in
+the
+<a href="#dfn-wot-scripting-api" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-scripting-api-19">
+WoT
+Scripting
+API
+</a>
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href="#bib-wot-scripting-api" title= "Web of Things (WoT) Scripting API">
+WOT-SCRIPTING-API
+</a>
+</cite>
+]).
+</p>
+<p>
+When
+using
+the
+<a href="#dfn-wot-scripting-api" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-scripting-api-20">
+WoT
+Scripting
+API
+</a>,
+<a href= "#dfn-exposed-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-exposed-thing-14">
+Exposed
+Thing
+</a>
+and
+<a href= "#dfn-consumed-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumed-thing-15">
+Consumed
+Thing
+</a>
+are
+JavaScript
+objects,
+which
+can
+be
+created,
+operated
+on,
+and
+destroyed
+by
+application
+scripts.
+However,
+access
+may
+be
+restricted
+through
+a
+security
+mechanism,
+for
+instance,
+in
+multi-tenant
+<a href= "#dfn-servient" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-servient-33">
+Servients
+</a>.
+</p>
+</section>
+<section id="private-security-data">
+<div class="header-wrapper">
+<h3 id="x8-5-private-security-data">
+<bdi class="secno">
+8.5
+</bdi>
+Private
+Security
+Data
+</h3>
+<a class="self-link" href="#private-security-data" aria-label= "Permalink for Section 8.5">
+</a>
+</div>
+<p>
+Private
+security
+data,
+such
+as
+a
+secret
+key
+for
+interacting
+with
+the
+Thing,
+is
+also
+conceptually
+managed
+by
+the
+<a href= "#dfn-wot-runtime" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-runtime-18">
+WoT
+Runtime
+</a>,
+but
+is
+intentionally
+not
+made
+directly
+accessible
+to
+the
+application.
+In
+fact,
+in
+the
+most
+secure
+hardware
+implementations,
+such
+<a href= "#dfn-private-security-data" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-private-security-data-3">
+Private
+Security
+Data
+</a>
+is
+stored
+in
+a
+separate,
+isolated
+memory
+(e.g.,
+on
+a
+secure
+processing
+element
+or
+TPM)
+and
+only
+an
+abstract
+set
+of
+operations
+(possibly
+even
+implemented
+by
+an
+isolated
+processor
+and
+software
+stack)
+is
+provided
+that
+limit
+the
+attack
+surface
+and
+prevent
+external
+disclosure
+of
+this
+data.
+<a href= "#dfn-private-security-data" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-private-security-data-4">
+Private
+Security
+Data
+</a>
+is
+used
+transparently
+by
+the
+<a href= "#dfn-wot-protocol-binding" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-wot-protocol-binding-13">
+Protocol
+Binding
+</a>
+to
+authorize
+and
+protect
+the
+integrity
+and
+confidentiality
+of
+interactions.
+</p>
+</section>
+<section id="protocol-stack-implementation">
+<div class="header-wrapper">
+<h3 id="x8-6-protocol-stack-implementation">
+<bdi class= "secno">
+8.6
+</bdi>
+Protocol
+Stack
+Implementation
+</h3>
+<a class="self-link" href="#protocol-stack-implementation" aria-label="Permalink for Section 8.6">
+</a>
+</div>
+<p>
+The
+protocol
+stack
+of
+a
+<a href="#dfn-servient" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-servient-34">
+Servient
+</a>
+implements
+the
+<a href= "#dfn-wot-interface" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-interface-8">
+WoT
+Interface
+</a>
+of
+the
+<a href= "#dfn-exposed-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-exposed-thing-15">
+Exposed
+Things
+</a>
+and
+is
+used
+by
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-consumer-61">
+Consumers
+</a>
+to
+access
+the
+<a href= "#dfn-wot-interface" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-interface-9">
+WoT
+Interface
+</a>
+of
+remote
+<a href= "#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-136">
+Things
+</a>
+(via
+<a href= "#dfn-consumed-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumed-thing-16">
+Consumed
+Things
+</a>
+).
+It
+produces
+the
+concrete
+protocol
+messages
+to
+interact
+over
+the
+network.
+<a href="#dfn-servient" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-servient-35">
+Servients
+</a>
+may
+implement
+multiple
+protocols,
+and
+hence
+support
+multiple
+<a href= "#dfn-wot-protocol-binding" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-wot-protocol-binding-14">
+Protocol
+Bindings
+</a>
+to
+enable
+interaction
+with
+different
+<a href= "#dfn-iot-platform" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-iot-platform-7">
+IoT
+Platforms
+</a>.
+</p>
+<p>
+In
+many
+cases,
+where
+standard
+protocols
+are
+used,
+generic
+protocol
+stacks
+can
+be
+used
+to
+produce
+the
+platform-specific
+messages
+(e.g.,
+one
+for
+HTTP(S)
+dialects,
+one
+for
+CoAP(S)
+dialects,
+and
+one
+for
+MQTT
+solutions,
+etc.).
+In
+this
+case,
+the
+communication
+metadata
+from
+the
+<a href="#dfn-thing-description" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-description-32">
+Thing
+Description
+</a>
+is
+used
+to
+select
+and
+configure
+the
+right
+stack
+(e.g.,
+HTTP
+with
+the
+right
+header
+fields
+or
+CoAP
+with
+the
+right
+options).
+Parsers
+and
+serializers
+for
+the
+expected
+payload
+representation
+format
+(JSON,
+CBOR,
+XML,
+etc.)
+as
+identified
+by
+the
+media
+type
+[
+<cite>
+<a class= "bibref" data-link-type="biblio" href="#bib-rfc2046" title= "Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types">
+RFC2046
+</a>
+</cite>
+]
+can
+also
+be
+shared
+across
+these
+generic
+protocol
+stacks.
+</p>
+<p>
+See
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-wot-binding-templates" title= "Web of Things (WoT) Binding Templates">
+WOT-BINDING-TEMPLATES
+</a>
+</cite>
+]
+for
+details.
+</p>
+</section>
+<section id="system-api">
+<div class="header-wrapper">
+<h3 id="x8-7-system-api">
+<bdi class="secno">
+8.7
+</bdi>
+System
+API
+</h3>
+<a class="self-link" href="#system-api" aria-label= "Permalink for Section 8.7">
+</a>
+</div>
+<p>
+An
+implementation
+of
+a
+<a href="#dfn-wot-runtime" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-runtime-19">
+WoT
+Runtime
+</a>
+may
+provide
+local
+hardware
+or
+system
+services
+to
+behavior
+implementations
+through
+the
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-137">
+Thing
+</a>
+abstraction,
+as
+if
+they
+were
+accessible
+over
+a
+communication
+protocol.
+In
+this
+case,
+the
+<a href="#dfn-wot-runtime" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-runtime-20">
+WoT
+Runtime
+</a>
+should
+enable
+the
+behavior
+implementation
+to
+instantiate
+<a href= "#dfn-consumed-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumed-thing-17">
+Consumed
+Things
+</a>
+that
+internally
+interface
+with
+the
+system
+instead
+of
+the
+protocol
+stack.
+This
+can
+be
+done
+by
+listing
+such
+system
+Things,
+which
+are
+only
+available
+in
+the
+local
+<a href="#dfn-wot-runtime" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-runtime-21">
+WoT
+Runtime
+</a>,
+in
+the
+results
+of
+the
+discovery
+mechanism
+provided
+by
+the
+application-facing
+<a href="#dfn-wot-runtime" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-runtime-22">
+WoT
+Runtime
+</a>
+API.
+</p>
+<p>
+A
+device
+may
+also
+be
+physically
+external
+to
+a
+<a href= "#dfn-servient" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-servient-36">
+Servient
+</a>,
+but
+connected
+via
+a
+proprietary
+protocol
+or
+a
+protocol
+not
+eligible
+as
+<a href= "#dfn-wot-interface" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-interface-10">
+WoT
+Interface
+</a>
+(see
+<a href= "#sec-protocol-bindings" class="sec-ref">
+<bdi class= "secno">
+6.7
+</bdi>
+Protocol
+Bindings
+</a>
+).
+In
+this
+case,
+the
+<a href="#dfn-wot-runtime" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-runtime-23">
+WoT
+Runtime
+</a>
+may
+access
+legacy
+devices
+with
+such
+protocols
+(e.g.,
+ECHONET
+Lite,
+BACnet,
+X10,
+I2C,
+SPI,
+etc.)
+through
+proprietary
+APIs,
+but
+may
+again
+choose
+to
+expose
+them
+to
+the
+behavior
+implementation
+via
+a
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-138">
+Thing
+</a>
+abstraction.
+A
+<a href= "#dfn-servient" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-servient-37">
+Servient
+</a>
+can
+then
+act
+as
+gateway
+to
+the
+legacy
+devices.
+This
+should
+only
+be
+done
+if
+the
+legacy
+device
+cannot
+be
+described
+directly
+using
+a
+<a href= "#dfn-wot-thing-description" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-wot-thing-description-22">
+WoT
+Thing
+Description
+</a>.
+</p>
+<p>
+The
+behavior
+implementation
+may
+also
+access
+local
+hardware
+or
+system
+services
+(e.g.,
+storage)
+through
+a
+proprietary
+API
+or
+other
+means.
+This
+is,
+however,
+out
+of
+scope
+of
+the
+<abbr title= "World Wide Web Consortium">
+W3C
+</abbr>
+WoT
+standardization,
+as
+it
+hinders
+portability.
+</p>
+</section>
+<section id="alt-servient-impl">
+<div class="header-wrapper">
+<h3 id="x8-8-alternative-servient-and-wot-implementations">
+<bdi class="secno">
+8.8
+</bdi>
+Alternative
+Servient
+and
+WoT
+Implementations
+</h3>
+<a class="self-link" href="#alt-servient-impl" aria-label= "Permalink for Section 8.8">
+</a>
+</div>
+<p>
+The
+<a href="#dfn-wot-scripting-api" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-scripting-api-21">
+WoT
+Scripting
+API
+</a>
+building
+block
+is
+optional.
+Alternative
+<a href= "#dfn-servient" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-servient-38">
+Servient
+</a>
+implementations
+are
+possible,
+where
+the
+<a href="#dfn-wot-runtime" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-runtime-24">
+WoT
+Runtime
+</a>
+offers
+an
+alternative
+API
+for
+the
+application
+logic,
+which
+may
+be
+written
+in
+any
+programming
+language.
+</p>
+<p>
+Furthermore,
+devices
+or
+services
+unaware
+of
+<abbr title= "World Wide Web Consortium">
+W3C
+</abbr>
+WoT
+can
+still
+be
+consumed,
+when
+it
+is
+possible
+to
+provide
+a
+well-formed
+<a href= "#dfn-wot-thing-description" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-wot-thing-description-23">
+WoT
+Thing
+Description
+</a>
+for
+them.
+In
+this
+case,
+the
+<a href="#dfn-td" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-td-31">
+TD
+</a>
+describes
+a
+<a href="#dfn-wot-interface" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-interface-11">
+WoT
+Interface
+</a>
+of
+a
+<a href= "#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-139">
+Thing
+</a>
+that
+has
+a
+black-box
+implementation.
+</p>
+<section id="native-impl">
+<div class="header-wrapper">
+<h4 id="x8-8-1-native-wot-api">
+<bdi class="secno">
+8.8.1
+</bdi>
+Native
+WoT
+API
+</h4>
+<a class="self-link" href="#native-impl" aria-label= "Permalink for Section 8.8.1">
+</a>
+</div>
+<p>
+There
+are
+various
+reasons
+why
+a
+developer
+may
+choose
+to
+implement
+a
+<a href="#dfn-servient" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-servient-39">
+Servient
+</a>
+without
+using
+the
+<a href="#dfn-wot-scripting-api" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-scripting-api-22">
+WoT
+Scripting
+API
+</a>.
+This
+may
+be
+due
+to
+insufficient
+memory
+or
+computing
+resources,
+so
+the
+developer
+cannot
+use
+the
+required
+software
+stack
+or
+a
+fully-featured
+scripting
+engine.
+Alternatively,
+to
+support
+their
+use
+case
+(for
+example,
+a
+proprietary
+communications
+protocol)
+the
+developer
+may
+have
+to
+use
+specific
+functions
+or
+libraries
+only
+available
+through
+a
+particular
+programming
+environment
+or
+language.
+</p>
+<p>
+In
+this
+case,
+a
+<a href="#dfn-wot-runtime" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-runtime-25">
+WoT
+Runtime
+</a>
+can
+still
+be
+used,
+but
+with
+an
+equivalent
+abstraction
+and
+functionality
+exposed
+using
+an
+alternative
+application-facing
+interface
+instead
+of
+the
+<a href="#dfn-wot-scripting-api" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-scripting-api-23">
+WoT
+Scripting
+API
+</a>.
+Except
+for
+the
+latter,
+all
+block
+descriptions
+in
+<a href= "#sec-servient-implementation" class="sec-ref">
+<bdi class= "secno">
+8.
+</bdi>
+Abstract
+Servient
+Architecture
+</a>
+are
+also
+valid
+for
+<a href="#architecture-implementation-native" class="fig-ref" title="Implementation of a Servient Using a Native WoT API">
+Figure
+<bdi class="">
+33
+</bdi>
+</a>.
+</p>
+<figure id="architecture-implementation-native">
+<img src= "images/servient/wot-thing-native.png" srcset= "images/servient/wot-thing-native.svg" class="wot-arch-diagram" alt="implementation native" />
+<figcaption>
+<a class="self-link" href= "#architecture-implementation-native">
+Figure
+<bdi class= "figno">
+33
+</bdi>
+</a>
+<span class="fig-title">
+Implementation
+of
+a
+Servient
+Using
+a
+Native
+WoT
+API
+</span>
+</figcaption>
+</figure>
+</section>
+<section id="existing-impl">
+<div class="header-wrapper">
+<h4 id="x8-8-2-thing-description-for-existing-devices">
+<bdi class= "secno">
+8.8.2
+</bdi>
+Thing
+Description
+for
+Existing
+Devices
+</h4>
+<a class="self-link" href="#existing-impl" aria-label= "Permalink for Section 8.8.2">
+</a>
+</div>
+<p>
+It
+is
+also
+possible
+to
+integrate
+<em>
+existing
+</em>
+IoT
+devices
+or
+services
+into
+the
+<abbr title= "World Wide Web Consortium">
+W3C
+</abbr>
+Web
+of
+Things
+and
+to
+use
+them
+as
+<a href="#dfn-thing" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-thing-140">
+Things
+</a>
+by
+creating
+a
+<a href= "#dfn-thing-description" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-description-33">
+Thing
+Description
+</a>
+for
+these
+devices
+or
+services.
+Such
+a
+TD
+can
+either
+be
+created
+manually
+or
+via
+a
+tool
+or
+service.
+For
+example,
+a
+TD
+could
+be
+generated
+by
+a
+service
+that
+provides
+automatic
+translation
+of
+metadata
+provided
+by
+another,
+ecosystem-dependent
+machine-readable
+format.
+This
+can
+only
+be
+done,
+however,
+if
+the
+target
+device
+is
+using
+protocols
+that
+can
+be
+described
+using
+a
+<a href="#dfn-wot-protocol-binding" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-protocol-binding-15">
+Protocol
+Binding
+</a>.
+The
+requirements
+for
+this
+are
+given
+in
+<a href="#sec-protocol-bindings" class="sec-ref">
+<bdi class="secno">
+6.7
+</bdi>
+Protocol
+Bindings
+</a>.
+Much
+of
+the
+previous
+discussion
+also
+implies
+that
+a
+<a href= "#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-141">
+Thing
+</a>
+provides
+its
+own
+<a href= "#dfn-thing-description" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-description-34">
+Thing
+Description
+</a>.
+While
+this
+is
+a
+useful
+pattern
+it
+is
+not
+mandatory.
+In
+particular,
+it
+may
+not
+be
+possible
+to
+modify
+existing
+devices
+to
+provide
+their
+own
+<a href="#dfn-thing-description" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-description-35">
+Thing
+Description
+</a>
+directly.
+In
+this
+case
+the
+<a href= "#dfn-thing-description" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-description-36">
+Thing
+Description
+</a>
+will
+have
+to
+be
+provided
+separately
+using
+a
+service
+such
+as
+a
+directory
+or
+some
+other
+external
+and
+separate
+distribution
+mechanism.
+</p>
+<figure id="architecture-implementation-existing">
+<img src= "images/servient/wot-thing-existing.png" srcset= "images/servient/wot-thing-existing.svg" class="wot-arch-diagram" alt="implementation existing" />
+<figcaption>
+<a class="self-link" href= "#architecture-implementation-existing">
+Figure
+<bdi class= "figno">
+34
+</bdi>
+</a>
+<span class="fig-title">
+Integration
+of
+Existing
+IoT
+Devices
+into
+<abbr title= "World Wide Web Consortium">
+W3C
+</abbr>
+WoT
+</span>
+</figcaption>
+</figure>
+</section>
+</section>
+</section>
+<section id="sec-deployment-scenario" class="informative">
+<div class="header-wrapper">
+<h2 id="x9-example-wot-deployments">
+<bdi class="secno">
+9.
+</bdi>
+Example
+WoT
+Deployments
+</h2>
+<a class="self-link" href="#sec-deployment-scenario" aria-label= "Permalink for Section 9.">
+</a>
+</div>
+<p>
+<em>
+This
+section
+is
+non-normative.
+</em>
+</p>
+<p>
+This
+section
+provides
+various
+examples
+of
+how
+the
+Web
+of
+Things
+(WoT)
+abstract
+architecture
+may
+be
+instantiated
+when
+devices
+and
+services
+that
+implement
+the
+<a href="#dfn-thing" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-142">
+Thing
+</a>
+and
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-62">
+Consumer
+</a>
+roles
+are
+connected
+in
+various
+concrete
+topologies
+and
+deployment
+scenarios.
+These
+topologies
+and
+scenarios
+are
+not
+normative,
+but
+are
+enabled
+and
+supported
+by
+the
+WoT
+abstract
+architecture.
+</p>
+<p>
+Before
+discussing
+specific
+topologies,
+we
+will
+first
+review
+the
+roles
+that
+<a href="#dfn-thing" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-thing-143">
+Things
+</a>
+and
+<a href= "#dfn-consumer" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-63">
+Consumers
+</a>
+can
+play
+in
+a
+WoT
+network
+and
+the
+relationships
+they
+have
+with
+the
+<a href= "#dfn-exposed-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-exposed-thing-16">
+Exposed
+Thing
+</a>
+and
+<a href= "#dfn-consumed-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumed-thing-18">
+Consumed
+Thing
+</a>
+software
+abstractions.
+<a href="#dfn-exposed-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-exposed-thing-17">
+Exposed
+Thing
+</a>
+and
+<a href="#dfn-consumed-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-consumed-thing-19">
+Consumed
+Thing
+</a>
+are
+internally
+available
+to
+the
+behavior
+implementations
+of
+<a href="#dfn-servient" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-servient-40">
+Servients
+</a>
+in
+the
+roles
+of
+<a href= "#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-144">
+Things
+</a>
+and
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-64">
+Consumers
+</a>,
+respectively.
+</p>
+<section id="sec-client-server-roles">
+<div class="header-wrapper">
+<h3 id="x9-1-thing-and-consumer-roles">
+<bdi class="secno">
+9.1
+</bdi>
+Thing
+and
+Consumer
+Roles
+</h3>
+<a class="self-link" href="#sec-client-server-roles" aria-label= "Permalink for Section 9.1">
+</a>
+</div>
+<p>
+A
+<a href="#dfn-servient" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-servient-41">
+Servient
+</a>
+in
+the
+role
+of
+a
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-145">
+Thing
+</a>
+creates
+an
+<a href= "#dfn-exposed-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-exposed-thing-18">
+Exposed
+Thing
+</a>
+based
+on
+a
+<a href="#dfn-thing-description" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-description-37">
+Thing
+Description
+</a>
+(TD).
+TDs
+are
+published
+and
+made
+available
+to
+other
+<a href="#dfn-servient" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-servient-42">
+Servients
+</a>
+that
+are
+in
+the
+roles
+of
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-consumer-65">
+Consumers
+</a>
+or
+<a href= "#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-35">
+Intermediaries
+</a>.
+TDs
+may
+be
+published
+in
+various
+different
+ways:
+the
+TD
+might
+be
+registered
+with
+a
+management
+system
+such
+as
+a
+<a href= "#dfn-wot-thing-description-directory" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-thing-description-directory-10">
+Thing
+Description
+Directory
+</a>
+service,
+or
+a
+<a href="#dfn-thing" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-146">
+Thing
+</a>
+may
+provide
+the
+requesters
+with
+a
+TD
+upon
+receiving
+a
+request
+for
+a
+TD.
+It
+is
+even
+possible
+to
+statically
+associate
+a
+TD
+with
+<a href="#dfn-thing" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-147">
+Thing
+</a>
+in
+certain
+application
+scenarios.
+</p>
+<p>
+A
+<a href="#dfn-servient" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-servient-43">
+Servient
+</a>
+in
+the
+role
+of
+a
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-consumer-66">
+Consumer
+</a>
+obtains
+the
+TD
+of
+a
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-148">
+Thing
+</a>
+using
+a
+discovery
+mechanism
+and
+creates
+a
+<a href="#dfn-consumed-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-consumed-thing-20">
+Consumed
+Thing
+</a>
+based
+on
+the
+obtained
+TD.
+The
+concrete
+discovery
+mechanism
+depends
+on
+the
+individual
+deployment
+scenario:
+It
+could
+be
+provided
+by
+a
+management
+system
+such
+as
+a
+<a href= "#dfn-wot-thing-description-directory" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-thing-description-directory-11">
+Thing
+Description
+Directory
+</a>,
+a
+discovery
+protocol,
+through
+static
+assignment,
+etc.
+As
+discussed
+elsewhere,
+use
+of
+the
+<a href= "#dfn-wot-discovery" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-discovery-15">
+Discovery
+</a>
+mechanisms
+defined
+in
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-wot-discovery" title= "Web of Things (WoT) Discovery">
+WOT-DISCOVERY
+</a>
+</cite>
+]
+is
+recommended
+whenever
+possible.
+</p>
+<p>
+However,
+it
+should
+be
+noted
+that
+TDs
+describing
+devices
+associated
+with
+an
+identifiable
+person
+may
+potentially
+be
+used
+to
+infer
+privacy-sensitive
+information.
+Constraints
+on
+the
+distribution
+of
+such
+TDs
+must
+therefore
+be
+incorporated
+into
+any
+concrete
+TD
+discovery
+mechanism.
+If
+possible,
+steps
+to
+limit
+the
+information
+exposed
+in
+a
+TD
+may
+also
+have
+to
+be
+taken,
+such
+as
+filtering
+out
+IDs
+or
+human-readable
+information
+if
+this
+is
+not
+strictly
+necessary
+for
+a
+particular
+use
+case.
+Privacy
+issues
+are
+discussed
+at
+a
+high
+level
+in
+<a href="#sec-privacy-considerations" class="sec-ref">
+<bdi class="secno">
+11.
+</bdi>
+Privacy
+Considerations
+</a>
+and
+a
+more
+detailed
+discussion
+is
+given
+in
+the
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-wot-thing-description" title= "Web of Things (WoT) Thing Description 1.1">
+WOT-THING-DESCRIPTION
+</a>
+</cite>
+]
+specification
+and
+are
+addressed
+in
+the
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href="#bib-wot-discovery" title= "Web of Things (WoT) Discovery">
+WOT-DISCOVERY
+</a>
+</cite>
+]
+specification.
+</p>
+<p>
+Internal
+system
+functions
+of
+a
+device,
+such
+as
+interacting
+with
+attached
+sensors
+and
+actuators,
+can
+also
+optionally
+be
+represented
+as
+<a href="#dfn-consumed-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-consumed-thing-21">
+Consumed
+Thing
+</a>
+abstractions.
+</p>
+<p>
+The
+functions
+supported
+by
+the
+<a href="#dfn-consumed-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumed-thing-22">
+Consumed
+Thing
+</a>
+are
+provided
+to
+the
+<a href="#dfn-consumer" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-consumer-67">
+Consumer
+</a>
+'s
+behavior
+implementation
+through
+a
+programming
+language
+interface.
+In
+the
+<a href="#dfn-wot-scripting-api" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-scripting-api-24">
+WoT
+Scripting
+API
+</a>,
+<a href="#dfn-consumed-thing" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumed-thing-23">
+Consumed
+Things
+</a>
+are
+represented
+by
+objects.
+The
+behavior
+implementation
+(that
+is,
+the
+application
+logic)
+running
+in
+a
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-149">
+Thing
+</a>
+can
+engage
+through
+<a href="#dfn-interaction-affordance" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-interaction-affordance-32">
+Interaction
+Affordances
+</a>
+with
+<a href="#dfn-consumer" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-consumer-68">
+Consumers
+</a>
+by
+using
+the
+programming
+language
+interface
+provided
+by
+the
+<a href= "#dfn-exposed-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-exposed-thing-19">
+Exposed
+Thing
+</a>.
+</p>
+<p>
+A
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-150">
+Thing
+</a>
+does
+not
+necessarily
+represent
+a
+physical
+device.
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-151">
+Things
+</a>
+can
+also
+represent
+a
+collection
+of
+devices,
+or
+virtual
+services
+running
+in
+a
+gateway
+or
+in
+the
+cloud.
+Likewise,
+a
+<a href="#dfn-consumer" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-69">
+Consumer
+</a>
+may
+represent
+an
+application
+or
+service
+running
+on
+a
+gateway
+or
+cloud.
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-70">
+Consumers
+</a>
+can
+also
+be
+implemented
+on
+edge
+devices.
+In
+<a href="#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-36">
+Intermediaries
+</a>,
+a
+single
+<a href= "#dfn-servient" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-servient-44">
+Servient
+</a>
+performs
+both
+the
+roles
+of
+a
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-152">
+Thing
+</a>
+and
+a
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-71">
+Consumer
+</a>
+simultaneously
+which
+are
+sharing
+a
+single
+<a href="#dfn-wot-runtime" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-runtime-26">
+WoT
+Runtime
+</a>.
+</p>
+</section>
+<section id="sec-topologies-deployment-scenarios">
+<div class="header-wrapper">
+<h3 id="x9-2-topology-of-wot-systems-and-deployment-scenarios">
+<bdi class="secno">
+9.2
+</bdi>
+Topology
+of
+WoT
+Systems
+and
+Deployment
+Scenarios
+</h3>
+<a class="self-link" href="#sec-topologies-deployment-scenarios" aria-label="Permalink for Section 9.2">
+</a>
+</div>
+<p>
+Various
+topologies
+and
+deployment
+scenarios
+of
+WoT
+systems
+are
+discussed
+in
+this
+section.
+These
+are
+only
+example
+patterns
+and
+other
+interconnection
+topologies
+are
+also
+possible.
+The
+topologies
+described
+here
+are
+derived
+from
+the
+Web
+of
+Things
+Use
+Cases
+and
+Requirements
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-wot-use-cases-requirements" title= "Web of Things (WoT) Use Cases and Requirements">
+WOT-USE-CASES-REQUIREMENTS
+</a>
+</cite>
+].
+</p>
+<section id="sec-deployment-app-dev">
+<div class="header-wrapper">
+<h4 id="x9-2-1-consumer-and-thing-on-the-same-network">
+<bdi class= "secno">
+9.2.1
+</bdi>
+Consumer
+and
+Thing
+on
+the
+Same
+Network
+</h4>
+<a class="self-link" href="#sec-deployment-app-dev" aria-label= "Permalink for Section 9.2.1">
+</a>
+</div>
+<p>
+In
+the
+simplest
+interconnection
+topology,
+illustrated
+by
+<a href="#simple-conf-application-device" class="fig-ref" title= "Consumer and Thing on the Same Network">
+Figure
+<bdi class= "">
+35
+</bdi>
+</a>,
+the
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-consumer-72">
+Consumer
+</a>
+and
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-153">
+Thing
+</a>
+are
+on
+the
+same
+network
+and
+can
+communicate
+directly
+with
+each
+other
+without
+any
+intermediaries.
+One
+use
+case
+where
+this
+topology
+arises
+is
+when
+the
+<a href= "#dfn-consumer" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-73">
+Consumer
+</a>
+is
+an
+orchestration
+service
+or
+some
+other
+IoT
+application
+running
+on
+a
+gateway
+and
+the
+<a href= "#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-154">
+Thing
+</a>
+is
+a
+device
+interfacing
+to
+a
+sensor
+or
+an
+actuator.
+However,
+the
+client/server
+relationship
+could
+be
+easily
+reversed;
+the
+client
+could
+be
+a
+device
+in
+the
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-consumer-74">
+Consumer
+</a>
+role
+accessing
+a
+service
+running
+as
+a
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-155">
+Thing
+</a>
+on
+a
+gateway
+or
+in
+the
+cloud.
+</p>
+<figure id="simple-conf-application-device">
+<img src= "images/deployments/arch-simple-conf-consumer-thing.png" srcset= "images/deployments/arch-simple-conf-consumer-thing.svg" class= "wot-arch-diagram" alt="consumer and thing on the same network" />
+<figcaption>
+<a class="self-link" href= "#simple-conf-application-device">
+Figure
+<bdi class= "figno">
+35
+</bdi>
+</a>
+<span class="fig-title">
+Consumer
+and
+Thing
+on
+the
+Same
+Network
+</span>
+</figcaption>
+</figure>
+<p>
+If
+the
+<a href="#dfn-thing" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-thing-156">
+Thing
+</a>
+is
+in
+the
+cloud
+and
+the
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-consumer-75">
+Consumer
+</a>
+is
+on
+a
+local
+network
+(see
+<a href="#smart-home" class="fig-ref" title= "Smart Home">
+Figure
+<bdi class="">
+1
+</bdi>
+</a>
+for
+an
+example
+in
+a
+Smart
+Home
+use
+case)
+the
+actual
+network
+topology
+may
+be
+more
+complex,
+for
+example
+requiring
+NAT
+traversal
+and
+disallowing
+certain
+forms
+of
+discovery.
+In
+such
+cases
+one
+of
+the
+more
+complex
+topologies
+discussed
+later
+may
+be
+more
+appropriate.
+</p>
+</section>
+<section id="sec-deployment-intermediaries">
+<div class="header-wrapper">
+<h4 id="x9-2-2-consumer-and-thing-connected-via-intermediaries">
+<bdi class="secno">
+9.2.2
+</bdi>
+Consumer
+and
+Thing
+Connected
+via
+Intermediaries
+</h4>
+<a class="self-link" href="#sec-deployment-intermediaries" aria-label="Permalink for Section 9.2.2">
+</a>
+</div>
+<p>
+An
+<a href="#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-37">
+Intermediary
+</a>
+plays
+both
+<a href= "#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-157">
+Thing
+</a>
+and
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-76">
+Consumer
+</a>
+roles
+on
+the
+network
+and
+supports
+both
+the
+<a href="#dfn-exposed-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-exposed-thing-20">
+Exposed
+Thing
+</a>
+and
+<a href="#dfn-consumed-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-consumed-thing-24">
+Consumed
+Thing
+</a>
+software
+abstractions
+within
+its
+<a href= "#dfn-wot-runtime" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-runtime-27">
+WoT
+Runtime
+</a>.
+<a href= "#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-38">
+Intermediaries
+</a>
+can
+be
+used
+for
+proxying
+between
+devices
+and
+networks
+or
+for
+<a href= "#dfn-digital-twin" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-digital-twin-4">
+Digital
+Twins
+</a>.
+</p>
+<section id="sec-deployment-app-proxy-dev">
+<div class="header-wrapper">
+<h5 id="x9-2-2-1-intermediary-acting-as-a-proxy">
+<bdi class= "secno">
+9.2.2.1
+</bdi>
+Intermediary
+Acting
+as
+a
+Proxy
+</h5>
+<a class="self-link" href="#sec-deployment-app-proxy-dev" aria-label="Permalink for Section 9.2.2.1">
+</a>
+</div>
+<p>
+One
+simple
+application
+of
+an
+<a href="#dfn-intermediary" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-39">
+Intermediary
+</a>
+is
+a
+proxy
+for
+a
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-158">
+Thing
+</a>.
+When
+the
+<a href= "#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-40">
+Intermediary
+</a>
+acts
+as
+a
+proxy,
+it
+has
+interfaces
+with
+two
+separate
+networks
+or
+protocols.
+This
+may
+involve
+the
+implementation
+of
+additional
+security
+mechanisms
+such
+as
+providing
+TLS
+endpoints.
+Generally
+proxies
+do
+not
+modify
+the
+set
+of
+interactions,
+so
+the
+TD
+exposed
+by
+the
+<a href= "#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-41">
+Intermediary
+</a>
+will
+have
+the
+same
+interactions
+as
+the
+consumed
+TD,
+however
+the
+connection
+metadata
+is
+modified.
+</p>
+<p>
+To
+implement
+this
+proxy
+pattern,
+the
+<a href="#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-42">
+Intermediary
+</a>
+obtains
+a
+TD
+of
+a
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-159">
+Thing
+</a>
+and
+creates
+a
+<a href= "#dfn-consumed-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumed-thing-25">
+Consumed
+Thing
+</a>.
+It
+creates
+a
+proxy
+object
+of
+the
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-160">
+Thing
+</a>
+as
+a
+software
+implementation
+that
+has
+the
+same
+<a href= "#dfn-interaction-affordance" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-interaction-affordance-33">
+Interaction
+Affordances
+</a>.
+It
+then
+creates
+a
+TD
+for
+the
+proxy
+object
+with
+a
+new
+identifier
+and
+possibly
+with
+new
+communications
+metadata
+(
+<a href="#dfn-wot-protocol-binding" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-protocol-binding-16">
+Protocol
+Bindings
+</a>
+)
+and/or
+new
+<a href="#dfn-public-security-metadata" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-public-security-metadata-4">
+Public
+Security
+Metadata
+</a>.
+Finally,
+an
+<a href="#dfn-exposed-thing" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-exposed-thing-21">
+Exposed
+Thing
+</a>
+is
+created
+based
+on
+this
+TD,
+and
+the
+<a href="#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-43">
+Intermediary
+</a>
+notifies
+other
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-consumer-77">
+Consumers
+</a>
+or
+<a href= "#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-44">
+Intermediaries
+</a>
+of
+the
+TD
+via
+an
+appropriate
+publication
+mechanism.
+</p>
+<figure id="simple-conf-application-intermediary-device">
+<img src= "images/deployments/arch-simple-conf-consumer-intermediary-thing.png" srcset= "images/deployments/arch-simple-conf-consumer-intermediary-thing.svg" class="wot-arch-diagram" alt= "consumer and thing connected via an intermediary acting as a proxy" />
+<figcaption>
+<a class="self-link" href= "#simple-conf-application-intermediary-device">
+Figure
+<bdi class= "figno">
+36
+</bdi>
+</a>
+<span class="fig-title">
+Consumer
+and
+Thing
+Connect
+via
+an
+Intermediary
+Acting
+as
+a
+Proxy
+</span>
+</figcaption>
+</figure>
+</section>
+<section id="sec-deployment-digital-twin">
+<div class="header-wrapper">
+<h5 id="x9-2-2-2-intermediary-acting-as-a-digital-twin">
+<bdi class= "secno">
+9.2.2.2
+</bdi>
+Intermediary
+Acting
+as
+a
+Digital
+Twin
+</h5>
+<a class="self-link" href="#sec-deployment-digital-twin" aria-label="Permalink for Section 9.2.2.2">
+</a>
+</div>
+<p>
+More
+complex
+<a href="#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-45">
+Intermediaries
+</a>
+may
+be
+known
+as
+<a href="#dfn-digital-twin" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-digital-twin-5">
+Digital
+Twins
+</a>.
+A
+<a href= "#dfn-digital-twin" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-digital-twin-6">
+Digital
+Twin
+</a>
+may
+or
+may
+not
+modify
+the
+protocols
+or
+translate
+between
+networks,
+but
+they
+provide
+additional
+services,
+such
+as
+state
+caching,
+deferred
+updates,
+or
+even
+predictive
+simulation
+of
+the
+behavior
+of
+the
+target
+device.
+For
+example,
+if
+an
+IoT
+device
+has
+limited
+power,
+it
+may
+choose
+to
+wake
+up
+relatively
+infrequently,
+synchronize
+with
+a
+<a href= "#dfn-digital-twin" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-digital-twin-7">
+Digital
+Twin
+</a>,
+and
+then
+immediately
+go
+to
+sleep
+again.
+In
+this
+case,
+typically
+the
+<a href= "#dfn-digital-twin" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-digital-twin-8">
+Digital
+Twins
+</a>
+runs
+on
+a
+less
+power-constrained
+device
+(such
+as
+in
+the
+cloud
+or
+on
+a
+gateway),
+(c.f.
+<a href="#device-categories">
+Device
+Categories
+</a>
+)
+and
+is
+able
+to
+respond
+to
+interactions
+on
+the
+constrained
+device's
+behalf.
+Requests
+for
+the
+current
+state
+of
+properties
+may
+also
+be
+satisfied
+by
+the
+<a href="#dfn-digital-twin" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-digital-twin-9">
+Digital
+Twins
+</a>
+using
+cached
+state.
+Requests
+that
+arrive
+when
+the
+target
+IoT
+device
+is
+sleeping
+may
+be
+queued
+and
+sent
+to
+it
+when
+it
+wakes
+up.
+To
+implement
+this
+pattern,
+the
+<a href="#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-46">
+Intermediary
+</a>,
+i.e.,
+the
+<a href= "#dfn-digital-twin" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-digital-twin-10">
+Digital
+Twin
+</a>
+needs
+to
+know
+when
+the
+device
+is
+awake.
+The
+device
+implementation
+as
+a
+<a href= "#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-161">
+Thing
+</a>
+may
+need
+to
+include
+a
+notification
+mechanism
+for
+that.
+This
+could
+be
+implemented
+using
+a
+separate
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-78">
+Consumer
+</a>
+/
+<a href="#dfn-thing" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-162">
+Thing
+</a>
+pair,
+or
+by
+using
+<a href= "#dfn-event" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-event-9">
+Event
+</a>
+interactions
+for
+this
+purpose.
+</p>
+</section>
+</section>
+<section id="sec-deployment-cloud">
+<div class="header-wrapper">
+<h4 id= "x9-2-3-devices-in-a-local-network-controlled-from-a-cloud-service">
+<bdi class="secno">
+9.2.3
+</bdi>
+Devices
+in
+a
+Local
+Network
+Controlled
+from
+a
+Cloud
+Service
+</h4>
+<a class="self-link" href="#sec-deployment-cloud" aria-label= "Permalink for Section 9.2.3">
+</a>
+</div>
+<p>
+In
+Smart
+Home
+use
+cases,
+devices
+(sensors
+and
+home
+appliances)
+connected
+to
+a
+home
+network
+are
+often
+monitored
+and,
+in
+some
+cases,
+also
+controlled
+by
+cloud
+services.
+There
+is
+usually
+a
+NAT
+device
+between
+the
+home
+network
+to
+which
+the
+devices
+are
+connected
+and
+the
+cloud.
+The
+NAT
+device
+translates
+IP
+addresses
+as
+well
+as
+often
+providing
+firewall
+services,
+which
+block
+connections
+selectively.
+The
+local
+devices
+and
+cloud
+services
+can
+only
+communicate
+with
+each
+other
+if
+the
+communication
+can
+successfully
+traverse
+the
+gateway.
+</p>
+<p>
+A
+typical
+structure,
+adopted
+in
+ITU-T
+Recommendation
+Y.4409/Y.2070
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href="#bib-y.4409-y.2070" title= "ITU-T Rec. Y.4409/Y.2070 (01/2015) Requirements and architecture of the home energy management system and home network services ">
+Y.4409-Y.2070
+</a>
+</cite>
+]
+,
+is
+shown
+in
+<a href="#deployment-cloud-device" class="fig-ref" title= "Cloud Applications Implemented as Consumers Connected to Local Devices implemented as Things via Paired Intermediaries">
+Figure
+<bdi class="">
+37
+</bdi>
+</a>.
+In
+this
+structure
+there
+is
+both
+a
+local
+and
+a
+remote
+<a href="#dfn-intermediary" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-47">
+Intermediary
+</a>.
+The
+local
+<a href= "#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-48">
+Intermediary
+</a>
+aggregates
+the
+<a href="#dfn-interaction-affordance" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-interaction-affordance-34">
+Interaction
+Affordances
+</a>
+from
+multiple
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-163">
+Thing
+</a>
+into
+a
+(set
+of)
+<a href="#dfn-exposed-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-exposed-thing-22">
+Exposed
+Things
+</a>,
+which
+can
+all
+be
+mapped
+onto
+a
+common
+protocol
+(for
+example,
+HTTP,
+with
+all
+interactions
+mapped
+to
+a
+single
+URL
+namespace
+with
+a
+common
+base
+server
+and
+using
+a
+single
+port).
+This
+provides
+the
+remote
+<a href="#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-49">
+Intermediary
+</a>
+with
+a
+simple
+way
+to
+access
+all
+the
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-164">
+Things
+</a>
+behind
+the
+NAT
+device,
+assuming
+the
+local
+<a href="#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-50">
+Intermediary
+</a>
+has
+used
+a
+converged
+protocol
+that
+can
+traverse
+the
+NAT
+device
+and
+has
+some
+way
+to
+expose
+this
+service
+to
+the
+Internet
+(STUN,
+TURN,
+dynamic
+DNS,
+etc.).
+In
+addition,
+the
+local
+<a href="#dfn-intermediary" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-51">
+Intermediary
+</a>
+can
+function
+as
+a
+Thing
+proxy,
+so
+even
+when
+the
+connected
+<a href="#dfn-thing" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-165">
+Things
+</a>
+each
+use
+a
+different
+protocol
+(HTTP,
+MQTT,
+CoAP,
+etc.)
+and/or
+a
+different
+set
+of
+ecosystem
+conventions,
+the
+<a href="#dfn-exposed-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-exposed-thing-23">
+Exposed
+Thing
+</a>
+can
+converge
+them
+into
+a
+single
+protocol
+so
+that
+<a href= "#dfn-consumer" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-79">
+Consumers
+</a>
+do
+not
+need
+to
+be
+aware
+of
+the
+various
+protocols
+the
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-166">
+Things
+</a>
+use.
+</p>
+<p>
+In
+<a href="#deployment-cloud-device" class="fig-ref" title= "Cloud Applications Implemented as Consumers Connected to Local Devices implemented as Things via Paired Intermediaries">
+Figure
+<bdi class="">
+37
+</bdi>
+</a>,
+there
+are
+two
+clients
+connected
+to
+the
+remote
+<a href="#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-52">
+Intermediary
+</a>,
+which
+has
+aggregated
+the
+services
+that
+reside
+behind
+the
+NAT
+border
+and
+may
+provide
+additional
+protocol
+translation
+or
+security
+services.
+In
+particular,
+the
+local
+<a href="#dfn-intermediary" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-53">
+Intermediary
+</a>
+may
+be
+on
+a
+network
+with
+limited
+capacity
+and
+making
+that
+service
+directly
+available
+to
+all
+users
+may
+not
+be
+feasible.
+In
+this
+case
+access
+to
+the
+local
+<a href="#dfn-intermediary" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-intermediary-54">
+Intermediary
+</a>
+is
+<em>
+only
+</em>
+provided
+to
+the
+remote
+<a href="#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-55">
+Intermediary
+</a>.
+The
+remote
+<a href= "#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-56">
+Intermediary
+</a>
+then
+implements
+a
+more
+general
+access
+control
+mechanism
+and
+may
+also
+perform
+caching
+or
+throttling
+to
+protect
+the
+consumer
+from
+excess
+traffic.
+Those
+consumers
+also
+will
+use
+a
+single
+protocol
+suitable
+for
+the
+open
+Internet
+(e.g.,
+HTTPS)
+to
+communicate
+with
+the
+<a href= "#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-57">
+Intermediary
+</a>,
+which
+makes
+the
+development
+of
+clients
+much
+simpler.
+</p>
+<p>
+In
+this
+topology
+there
+is
+NAT
+and
+firewall
+functionality
+between
+the
+consumers
+and
+things,
+but
+the
+local
+and
+remote
+<a href= "#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-58">
+Intermediaries
+</a>
+work
+together
+to
+tunnel
+all
+communications
+through
+the
+firewall,
+so
+the
+consumers
+and
+things
+need
+to
+know
+nothing
+about
+the
+firewall.
+The
+paired
+<a href="#dfn-intermediary" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-intermediary-59">
+Intermediaries
+</a>
+also
+protect
+the
+home
+devices
+by
+providing
+access
+control
+and
+traffic
+management.
+</p>
+<figure id="deployment-cloud-device">
+<img src= "images/deployments/arch-deploy-cloud-thing.png" srcset= "images/deployments/arch-deploy-cloud-thing.svg" class= "wot-arch-diagram" alt="cloud applications" />
+<figcaption>
+<a class="self-link" href= "#deployment-cloud-device">
+Figure
+<bdi class="figno">
+37
+</bdi>
+</a>
+<span class="fig-title">
+Cloud
+Applications
+Implemented
+as
+Consumers
+Connected
+to
+Local
+Devices
+implemented
+as
+Things
+via
+Paired
+Intermediaries
+</span>
+</figcaption>
+</figure>
+<p>
+In
+more
+difficult
+cases
+the
+NAT
+and
+firewall
+traversal
+may
+not
+work
+exactly
+as
+shown.
+In
+particular,
+an
+ISP
+may
+not
+support
+publicly
+accessible
+addresses,
+or
+STUN/TURN
+and/or
+dynamic
+DNS
+may
+not
+be
+supported
+or
+available.
+In
+this
+case
+the
+<a href= "#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-60">
+Intermediaries
+</a>
+may
+alternative
+reverse
+the
+client/server
+roles
+between
+them
+to
+set
+up
+an
+initial
+connection
+(with
+the
+local
+<a href="#dfn-intermediary" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-61">
+Intermediary
+</a>
+first
+connecting
+to
+the
+remote
+<a href="#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-62">
+Intermediary
+</a>
+in
+the
+cloud),
+then
+the
+pair
+of
+<a href="#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-63">
+Intermediaries
+</a>
+may
+establish
+a
+tunnel
+(using
+for
+example,
+a
+Secure
+WebSocket,
+which
+uses
+TLS
+to
+protect
+the
+connection).
+The
+tunnel
+can
+then
+be
+used
+to
+encode
+all
+communications
+between
+the
+<a href="#dfn-intermediary" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-64">
+Intermediaries
+</a>
+using
+a
+custom
+protocol.
+In
+this
+case
+the
+initial
+connection
+can
+still
+be
+made
+over
+HTTPS
+using
+standard
+ports,
+and
+from
+the
+local
+<a href= "#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-65">
+Intermediary
+</a>
+to
+the
+remote
+<a href="#dfn-intermediary" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-intermediary-66">
+Intermediary
+</a>
+identically
+to
+a
+normal
+browser/web
+server
+interaction.
+This
+should
+be
+able
+to
+traverse
+most
+home
+firewalls,
+and
+since
+the
+connection
+is
+outgoing,
+network
+address
+translation
+will
+not
+cause
+any
+problems.
+However,
+even
+though
+a
+custom
+tunneling
+protocol
+is
+needed,
+the
+remote
+<a href="#dfn-intermediary" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-intermediary-67">
+Intermediary
+</a>
+can
+still
+translate
+this
+custom
+protocol
+back
+into
+standard
+external
+protocols.
+The
+connected
+<a href="#dfn-consumer" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-80">
+Consumers
+</a>
+and
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-167">
+Things
+</a>
+do
+not
+need
+to
+know
+about
+it.
+It
+is
+also
+possible
+to
+extend
+this
+example
+to
+use
+cases
+where
+both
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-168">
+Things
+</a>
+and
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-81">
+Consumers
+</a>
+can
+connect
+on
+either
+side
+of
+the
+NAT
+boundary.
+This
+however
+also
+requires
+a
+bidirectional
+tunnel
+to
+be
+established
+between
+the
+two
+<a href= "#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-68">
+Intermediaries
+</a>.
+</p>
+</section>
+<section id="sec-deployment-discovery-with-directory">
+<div class="header-wrapper">
+<h4 id="x9-2-4-discovery-using-a-thing-description-directory">
+<bdi class="secno">
+9.2.4
+</bdi>
+Discovery
+Using
+a
+Thing
+Description
+Directory
+</h4>
+<a class="self-link" href= "#sec-deployment-discovery-with-directory" aria-label= "Permalink for Section 9.2.4">
+</a>
+</div>
+<p>
+Once
+local
+devices
+(and
+possibly
+services)
+can
+be
+monitored
+or
+controlled
+by
+services
+on
+cloud,
+a
+variety
+of
+additional
+services
+can
+be
+built
+on
+top.
+For
+example,
+a
+cloud
+application
+could
+change
+a
+device's
+operating
+condition
+based
+on
+an
+analysis
+of
+collected
+data.
+</p>
+<p>
+However
+when
+the
+remote
+<a href="#dfn-intermediary" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-69">
+Intermediary
+</a>
+is
+a
+part
+of
+a
+cloud
+platform
+servicing
+client
+applications,
+the
+clients
+need
+to
+be
+able
+to
+find
+device
+information
+by,
+for
+example,
+accessing
+a
+directory
+of
+connected
+devices.
+For
+simplicity
+in
+the
+figure
+below
+we
+have
+assumed
+all
+local
+devices
+are
+implemented
+as
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-169">
+Things
+</a>
+and
+all
+cloud
+applications
+as
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-consumer-82">
+Consumers
+</a>.
+To
+make
+the
+metadata
+of
+local
+devices
+implemented
+as
+<a href="#dfn-thing" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-170">
+Things
+</a>
+available
+to
+the
+cloud
+applications,
+their
+metadata
+can
+be
+registered
+with
+a
+<a href= "#dfn-wot-thing-description-directory" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-thing-description-directory-12">
+Thing
+Description
+Directory
+</a>
+service.
+This
+metadata
+is
+specifically
+the
+TDs
+of
+the
+local
+devices
+modified
+to
+reflect
+the
+<a href= "#dfn-public-security-metadata" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-public-security-metadata-5">
+Public
+Security
+Metadata
+</a>
+and
+communication
+metadata
+(
+<a href= "#dfn-wot-protocol-binding" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-wot-protocol-binding-17">
+Protocol
+Bindings
+</a>
+)
+provided
+by
+the
+remote
+<a href="#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-70">
+Intermediary
+</a>.
+A
+client
+application
+then
+can
+obtain
+the
+metadata
+it
+needs
+to
+communicate
+with
+local
+devices
+to
+achieve
+its
+functionality
+by
+querying
+the
+<a href="#dfn-wot-thing-description-directory" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-thing-description-directory-13">
+Thing
+Description
+Directory
+</a>.
+</p>
+<figure id="deployment-cloud-directory">
+<img src= "images/deployments/arch-deploy-service-directory.png" srcset= "images/deployments/arch-deploy-service-directory.svg" class= "wot-arch-diagram" alt="cloud directory" />
+<figcaption>
+<a class="self-link" href= "#deployment-cloud-directory">
+Figure
+<bdi class= "figno">
+38
+</bdi>
+</a>
+<span class="fig-title">
+Cloud
+Service
+with
+Thing
+Description
+Directory
+</span>
+</figcaption>
+</figure>
+<p>
+In
+more
+complex
+situations,
+not
+shown
+in
+the
+figure,
+there
+may
+also
+be
+cloud
+services
+that
+act
+as
+<a href="#dfn-thing" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-171">
+Things
+</a>.
+These
+can
+also
+register
+themselves
+with
+a
+<a href="#dfn-wot-thing-description-directory" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-thing-description-directory-14">
+Thing
+Description
+Directory
+</a>.
+Since
+a
+<a href= "#dfn-wot-thing-description-directory" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-thing-description-directory-15">
+Thing
+Description
+Directory
+</a>
+is
+a
+Web
+service,
+it
+should
+be
+visible
+to
+the
+local
+devices
+through
+the
+NAT
+or
+firewall
+device
+and
+its
+interface
+can
+even
+be
+provided
+with
+its
+own
+TD.
+Local
+devices
+acting
+as
+<a href= "#dfn-consumer" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-83">
+Consumers
+</a>
+can
+then
+discover
+the
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-172">
+Things
+</a>
+in
+the
+cloud
+via
+a
+<a href= "#dfn-wot-thing-description-directory" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-thing-description-directory-16">
+Thing
+Description
+Directory
+</a>
+and
+connect
+to
+the
+<a href="#dfn-thing" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-173">
+Things
+</a>
+directly
+or
+via
+the
+local
+<a href="#dfn-intermediary" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-intermediary-71">
+Intermediary
+</a>
+if,
+for
+instance,
+protocol
+translation
+is
+needed.
+</p>
+</section>
+<section id="sec-deployment-service-to-service">
+<div class="header-wrapper">
+<h4 id= "x9-2-5-service-to-service-connections-across-multiple-domains">
+<bdi class="secno">
+9.2.5
+</bdi>
+Service-to-Service
+Connections
+Across
+Multiple
+Domains
+</h4>
+<a class="self-link" href="#sec-deployment-service-to-service" aria-label="Permalink for Section 9.2.5">
+</a>
+</div>
+<p>
+Multiple
+cloud
+eco-systems
+each
+based
+on
+different
+IoT
+platforms
+can
+work
+together
+to
+make
+a
+larger,
+system-of-systems
+eco-system.
+Building
+on
+the
+previously
+discussed
+structure
+of
+a
+cloud
+application
+eco-system,
+the
+figure
+below
+shows
+two
+eco-systems
+connected
+to
+each
+other
+to
+make
+a
+system-of-systems.
+Consider
+the
+case
+in
+which
+a
+client
+in
+one
+eco-system
+(i.e.,
+<a href= "#dfn-consumer" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-84">
+Consumer
+</a>
+A
+below)
+needs
+to
+use
+a
+server
+in
+another
+eco-system
+(i.e.,
+<a href="#dfn-thing" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-174">
+Thing
+</a>
+B
+below).
+There
+is
+more
+than
+one
+mechanism
+to
+achieve
+this
+cross
+eco-systems
+application-device
+integration.
+Below,
+two
+mechanisms
+are
+explained,
+each
+using
+a
+figure,
+to
+show
+how
+this
+can
+be
+achieved.
+</p>
+<section id="sec-deployment-service-to-service-synchronized">
+<div class="header-wrapper">
+<h5 id= "x9-2-5-1-connection-through-thing-description-directory-synchronization">
+<bdi class="secno">
+9.2.5.1
+</bdi>
+Connection
+Through
+Thing
+Description
+Directory
+Synchronization
+</h5>
+<a class="self-link" href= "#sec-deployment-service-to-service-synchronized" aria-label= "Permalink for Section 9.2.5.1">
+</a>
+</div>
+<p>
+In
+<a href="#deployment-service-sync-directory" class="fig-ref" title= "Multiple Cloud Connections Through Thing Description Directory Synchronization">
+Figure
+<bdi class="">
+39
+</bdi>
+</a>,
+two
+instances
+of
+a
+<a href= "#dfn-wot-thing-description-directory" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-thing-description-directory-17">
+Thing
+Description
+Directory
+</a>
+synchronize
+information,
+which
+makes
+it
+possible
+for
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-consumer-85">
+Consumer
+</a>
+A
+to
+obtain
+the
+information
+of
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-175">
+Thing
+</a>
+B
+through
+<a href="#dfn-wot-thing-description-directory" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-thing-description-directory-18">
+Thing
+Description
+Directory
+</a>
+A.
+As
+described
+in
+previous
+sections,
+remote
+<a href= "#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-72">
+Intermediary
+</a>
+B
+maintains
+a
+shadow
+implementation
+of
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-176">
+Thing
+</a>
+B.
+By
+obtaining
+the
+TD
+of
+this
+shadow
+device,
+<a href="#dfn-consumer" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-consumer-86">
+Consumer
+</a>
+A
+is
+able
+to
+use
+<a href= "#dfn-thing" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-177">
+Thing
+</a>
+B
+through
+the
+remote
+<a href= "#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-73">
+Intermediary
+</a>
+B.
+</p>
+<figure id="deployment-service-sync-directory">
+<img src= "images/deployments/arch-deploy-service-sync-directory.png" srcset= "images/deployments/arch-deploy-service-sync-directory.svg" class= "wot-arch-diagram" alt="service sync directory" />
+<figcaption>
+<a class="self-link" href= "#deployment-service-sync-directory">
+Figure
+<bdi class= "figno">
+39
+</bdi>
+</a>
+<span class="fig-title">
+Multiple
+Cloud
+Connections
+Through
+Thing
+Description
+Directory
+Synchronization
+</span>
+</figcaption>
+</figure>
+</section>
+<section id="sec-deployment-service-sync-proxy">
+<div class="header-wrapper">
+<h5 id="x9-2-5-2-connection-through-proxy-synchronization">
+<bdi class="secno">
+9.2.5.2
+</bdi>
+Connection
+Through
+Proxy
+Synchronization
+</h5>
+<a class="self-link" href="#sec-deployment-service-sync-proxy" aria-label="Permalink for Section 9.2.5.2">
+</a>
+</div>
+<p>
+In
+<a href="#deployment-service-sync-intermediary" class= "fig-ref" title= "Multiple Cloud Connections Through Intermediary Synchronization">
+Figure
+<bdi class="">
+40
+</bdi>
+</a>,
+two
+remote
+<a href="#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-74">
+Intermediaries
+</a>
+synchronize
+device
+information.
+When
+a
+shadow
+of
+<a href="#dfn-thing" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-thing-178">
+Thing
+</a>
+B
+is
+created
+in
+remote
+<a href= "#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-75">
+Intermediary
+</a>
+B,
+the
+TD
+of
+the
+shadow
+is
+simultaneously
+synchronized
+into
+remote
+<a href= "#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-76">
+Intermediary
+</a>
+A.
+Remote
+<a href= "#dfn-intermediary" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-intermediary-77">
+Intermediary
+</a>
+A
+in
+turn
+creates
+its
+own
+shadow
+of
+<a href="#dfn-thing" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-thing-179">
+Thing
+</a>
+B,
+and
+registers
+the
+TD
+with
+<a href= "#dfn-wot-thing-description-directory" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-thing-description-directory-19">
+Thing
+Description
+Directory
+</a>
+A.
+With
+this
+mechanism,
+synchronization
+between
+<a href="#dfn-wot-thing-description-directory" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-thing-description-directory-20">
+Thing
+Description
+Directory
+</a>
+services
+is
+not
+necessary.
+</p>
+<figure id="deployment-service-sync-intermediary">
+<img src= "images/deployments/arch-deploy-service-sync-intermediary.png" srcset= "images/deployments/arch-deploy-service-sync-intermediary.svg" class="wot-arch-diagram" alt="service sync intermediary" />
+<figcaption>
+<a class="self-link" href= "#deployment-service-sync-intermediary">
+Figure
+<bdi class= "figno">
+40
+</bdi>
+</a>
+<span class="fig-title">
+Multiple
+Cloud
+Connections
+Through
+Intermediary
+Synchronization
+</span>
+</figcaption>
+</figure>
+</section>
+</section>
+</section>
+</section>
+<section id="sec-security-considerations">
+<div class="header-wrapper">
+<h2 id="x10-security-considerations">
+<bdi class="secno">
+10.
+</bdi>
+Security
+Considerations
+</h2>
+<a class="self-link" href="#sec-security-considerations" aria-label="Permalink for Section 10.">
+</a>
+</div>
+<p>
+Security
+is
+a
+cross-cutting
+issue
+that
+needs
+to
+be
+considered
+in
+all
+<a href="#sec-building-blocks">
+WoT
+building
+blocks
+</a>
+and
+WoT
+implementations.
+This
+chapter
+summarizes
+some
+general
+issues
+and
+guidelines
+to
+help
+preserve
+the
+security
+of
+concrete
+WoT
+implementations.
+However,
+these
+are
+only
+general
+guidelines
+and
+an
+abstract
+architecture
+such
+as
+described
+in
+this
+document
+cannot,
+itself,
+guarantee
+security.
+Instead
+the
+details
+of
+a
+concrete
+implementation
+need
+to
+be
+considered.
+For
+a
+more
+detailed
+and
+complete
+analysis
+of
+security
+(and
+privacy)
+issues,
+see
+the
+<em>
+WoT
+Security
+and
+Privacy
+Guidelines
+</em>
+document
+[
+<cite>
+<a class= "bibref" data-link-type="biblio" href="#bib-wot-security" title= "Web of Things (WoT) Security and Privacy Guidelines">
+WOT-SECURITY
+</a>
+</cite>
+].
+</p>
+<p>
+Overall,
+the
+goal
+of
+the
+WoT
+is
+to
+describe
+the
+existing
+access
+mechanisms
+and
+properties
+of
+IoT
+devices
+and
+services,
+including
+security.
+In
+general,
+<abbr title= "World Wide Web Consortium">
+W3C
+</abbr>
+WoT
+is
+designed
+to
+describe
+what
+exists
+rather
+than
+to
+prescribe
+what
+to
+implement.
+A
+description
+of
+an
+existing
+system
+should
+accurately
+describe
+that
+system,
+even
+if
+it
+has
+less
+than
+ideal
+security
+behavior.
+A
+clear
+understanding
+of
+the
+security
+vulnerabilities
+of
+a
+system
+supports
+security
+mitigations—although
+of
+course
+such
+data
+need
+not
+be
+distributed
+to
+those
+who
+might
+maliciously
+exploit
+it.
+</p>
+<p>
+However,
+especially
+for
+new
+systems,
+the
+WoT
+architecture
+should
+<em>
+enable
+</em>
+the
+use
+of
+best
+practices.
+In
+general,
+the
+WoT
+security
+architecture
+must
+support
+the
+goals
+and
+mechanisms
+of
+the
+IoT
+protocols
+and
+systems
+it
+connects
+to.
+These
+systems
+vary
+in
+their
+security
+requirements
+and
+risk
+tolerance,
+so
+security
+mechanisms
+will
+also
+vary
+based
+on
+these
+factors.
+</p>
+<p>
+Security
+is
+especially
+important
+in
+the
+IoT
+domain
+since
+IoT
+devices
+need
+to
+operate
+autonomously
+and,
+in
+many
+cases,
+may
+be
+in
+control
+of
+safety-critical
+systems.
+IoT
+devices
+are
+subject
+to
+different
+and
+in
+some
+cases
+higher
+risks
+than
+IT
+systems.
+It
+is
+also
+important
+to
+protect
+IoT
+systems
+so
+that
+they
+cannot
+be
+used
+to
+launch
+attacks
+on
+other
+computer
+systems.
+</p>
+<p>
+In
+general,
+security
+cannot
+be
+guaranteed.
+It
+is
+not
+possible
+for
+the
+WoT
+to
+turn
+an
+insecure
+system
+into
+a
+secure
+one.
+However,
+the
+WoT
+architecture
+needs
+to
+do
+no
+harm:
+it
+should
+support
+security
+at
+least
+as
+well
+as
+the
+systems
+it
+describes
+and
+supports.
+</p>
+<section id="sec-security-consideration-td-risks">
+<div class="header-wrapper">
+<h3 id="x10-1-wot-thing-description-risks">
+<bdi class= "secno">
+10.1
+</bdi>
+WoT
+Thing
+Description
+Risks
+</h3>
+<a class="self-link" href="#sec-security-consideration-td-risks" aria-label="Permalink for Section 10.1">
+</a>
+</div>
+<p>
+The
+metadata
+contained
+in
+a
+<a href="#dfn-wot-thing-description" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-thing-description-24">
+WoT
+Thing
+Description
+</a>
+(TD)
+is
+potentially
+sensitive.
+As
+a
+best
+practice,
+TDs
+should
+be
+used
+together
+with
+appropriate
+integrity
+protection
+mechanisms
+and
+access
+control
+policies,
+with
+the
+goal
+of
+providing
+it
+only
+to
+authorized
+users.
+</p>
+<p>
+Please
+refer
+to
+the
+Privacy
+Considerations
+sections
+of
+the
+WoT
+Thing
+Description
+specification
+for
+additional
+details
+and
+discussion
+of
+these
+points.
+</p>
+<section id="sec-security-consideration-td-private">
+<div class="header-wrapper">
+<h4 id="x10-1-1-thing-description-private-security-data-risk">
+<bdi class="secno">
+10.1.1
+</bdi>
+Thing
+Description
+Private
+Security
+Data
+Risk
+</h4>
+<a class="self-link" href="#sec-security-consideration-td-private" aria-label="Permalink for Section 10.1.1">
+</a>
+</div>
+<p>
+TDs
+are
+designed
+to
+carry
+only
+<a href= "#dfn-public-security-metadata" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-public-security-metadata-6">
+Public
+Security
+Metadata
+</a>.
+The
+built-in
+TD
+security
+schemes
+defined
+in
+the
+TD
+specification
+intentionally
+do
+not
+support
+the
+encoding
+of
+<a href= "#dfn-private-security-data" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-private-security-data-5">
+Private
+Security
+Data
+</a>.
+However,
+there
+is
+a
+risk
+that
+other
+fields
+such
+as
+human-readable
+descriptions
+might
+be
+misused
+to
+encode
+this
+information,
+or
+new
+security
+schemes
+might
+be
+defined
+and
+deployed
+via
+the
+extension
+mechanism
+that
+encode
+such
+information.
+</p>
+<dl>
+<dt>
+Mitigation:
+</dt>
+<dd>
+<span class="rfc2119-assertion" id= "arch-security-consideration-separate-security-data">
+There
+<em class="rfc2119">
+SHOULD
+</em>
+be
+a
+strict
+separation
+of
+<a href= "#dfn-public-security-metadata" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-public-security-metadata-7">
+Public
+Security
+Metadata
+</a>
+and
+<a href="#dfn-private-security-data" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-private-security-data-6">
+Private
+Security
+Data
+</a>.
+</span>
+<span class="rfc2119-assertion" id= "arch-security-consideration-auth-private-data">
+Authentication
+and
+authorization
+<em class="rfc2119">
+SHOULD
+</em>
+be
+established
+based
+on
+separately
+managed
+<a href="#dfn-private-security-data" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-private-security-data-7">
+Private
+Security
+Data
+</a>.
+</span>
+<span class="rfc2119-assertion" id= "arch-security-consideration-no-private-security-data">
+<a href= "#dfn-producer" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-producer-1">
+Producers
+</a>
+of
+TDs
+<em class= "rfc2119">
+MUST
+</em>
+ensure
+that
+no
+<a href= "#dfn-private-security-data" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-private-security-data-8">
+Private
+Security
+Data
+</a>
+is
+included
+in
+<a href="#dfn-td" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-td-32">
+TDs
+</a>.
+</span>
+</dd>
+</dl>
+</section>
+<section id="sec-security-consideration-td-cm">
+<div class="header-wrapper">
+<h4 id="x10-1-2-thing-description-communication-metadata-risk">
+<bdi class="secno">
+10.1.2
+</bdi>
+Thing
+Description
+Communication
+Metadata
+Risk
+</h4>
+<a class="self-link" href="#sec-security-consideration-td-cm" aria-label="Permalink for Section 10.1.2">
+</a>
+</div>
+<p>
+Without
+best-practice
+configuration
+of
+security
+mechanisms,
+communication
+with
+IoT
+devices
+is
+at
+greater
+risk
+of
+being
+intercepted
+or
+compromised.
+</p>
+<dl>
+<dt>
+Mitigation:
+</dt>
+<dd>
+Configure
+any
+communication
+security
+metadata
+for
+an
+<a href= "#dfn-iot-platform" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-iot-platform-8">
+IoT
+Platform
+</a>
+used
+with
+WoT
+following
+best
+practices
+for
+that
+<a href="#dfn-iot-platform" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-iot-platform-9">
+IoT
+Platform
+</a>.
+<span class= "rfc2119-assertion" id= "arch-security-consideration-communication-binding">
+Whenever
+possible,
+TD
+creators
+<em class="rfc2119">
+SHOULD
+</em>
+use
+the
+vetted
+communication
+metadata
+provided
+in
+the
+<a href= "#dfn-wot-binding-templates" class="internalDFN" data-link-type= "dfn" id="ref-for-dfn-wot-binding-templates-9">
+WoT
+Binding
+Templates
+</a>.
+</span>
+<span class="rfc2119-assertion" id= "arch-security-consideration-communication-platform">
+When
+generating
+TDs
+for
+an
+<a href="#dfn-iot-platform" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-iot-platform-10">
+IoT
+Platform
+</a>
+not
+covered
+by
+the
+<a href="#dfn-wot-binding-templates" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-binding-templates-10">
+WoT
+Binding
+Templates
+</a>,
+TD
+creators
+<em class="rfc2119">
+SHOULD
+</em>
+ensure
+that
+all
+the
+security
+requirements
+of
+the
+<a href= "#dfn-iot-platform" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-iot-platform-11">
+IoT
+Platform
+</a>
+are
+satisfied.
+</span>
+</dd>
+</dl>
+</section>
+</section>
+<section id="sec-security-consideration-scripting-risks">
+<div class="header-wrapper">
+<h3 id="x10-2-wot-scripting-api-risks">
+<bdi class= "secno">
+10.2
+</bdi>
+WoT
+Scripting
+API
+Risks
+</h3>
+<a class="self-link" href= "#sec-security-consideration-scripting-risks" aria-label= "Permalink for Section 10.2">
+</a>
+</div>
+<p>
+The
+<a href="#dfn-wot-runtime" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-runtime-28">
+WoT
+Runtime
+</a>
+implementation
+and
+the
+<a href="#dfn-wot-scripting-api" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-scripting-api-25">
+WoT
+Scripting
+API
+</a>
+should
+have
+mechanisms
+to
+prevent
+malicious
+access
+to
+the
+system
+and
+isolate
+scripts
+in
+multi-tenant
+<a href="#dfn-servient" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-servient-45">
+Servients
+</a>
+.
+More
+specifically
+the
+<a href="#dfn-wot-runtime" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-runtime-29">
+WoT
+Runtime
+</a>
+implementation
+when
+used
+with
+the
+<a href="#dfn-wot-scripting-api" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-scripting-api-26">
+WoT
+Scripting
+API
+</a>
+should
+consider
+the
+following
+security
+and
+privacy
+risks
+and
+implement
+the
+recommended
+mitigations.
+</p>
+<p>
+In
+general,
+these
+risks
+and
+mitigations
+should
+also
+be
+applied
+to
+any
+system
+that
+supports
+programmable
+behavior
+for
+WoT
+systems,
+not
+just
+the
+<a href="#dfn-wot-scripting-api" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-scripting-api-27">
+WoT
+Scripting
+API
+</a>.
+</p>
+<section id="sec-security-consideration-cross-script">
+<div class="header-wrapper">
+<h4 id="x10-2-1-cross-script-security-risk">
+<bdi class= "secno">
+10.2.1
+</bdi>
+Cross-Script
+Security
+Risk
+</h4>
+<a class="self-link" href= "#sec-security-consideration-cross-script" aria-label= "Permalink for Section 10.2.1">
+</a>
+</div>
+<p>
+In
+basic
+WoT
+setups,
+all
+scripts
+running
+inside
+the
+<a href= "#dfn-wot-runtime" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-runtime-30">
+WoT
+Runtime
+</a>
+are
+considered
+trusted,
+distributed
+by
+the
+manufacturer,
+and
+therefore
+there
+is
+no
+strong
+need
+to
+isolate
+script
+instances
+from
+each
+other.
+However,
+depending
+on
+device
+capabilities,
+deployment
+use
+case
+scenarios,
+and
+risk
+level
+it
+might
+be
+desirable
+to
+do
+so.
+For
+example,
+if
+one
+script
+handles
+sensitive
+data
+and
+is
+well-audited,
+it
+might
+be
+desirable
+to
+separate
+it
+from
+the
+rest
+of
+the
+script
+instances
+to
+minimize
+the
+risk
+of
+data
+exposure
+in
+case
+some
+other
+script
+inside
+the
+same
+system
+gets
+compromised
+during
+runtime.
+Another
+example
+is
+mutual
+co-existence
+of
+different
+tenants
+on
+a
+single
+WoT
+device.
+In
+this
+case
+each
+WoT
+runtime
+instance
+will
+be
+hosting
+a
+different
+tenant,
+and
+preventing
+tenants
+from
+accessing
+each
+other's
+data
+without
+authorization
+will
+generally
+be
+needed.
+</p>
+<dl>
+<dt>
+Mitigation:
+</dt>
+<dd>
+<span class="rfc2119-assertion" id= "arch-security-consideration-isolation-sensitive">
+The
+<a href= "#dfn-wot-runtime" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-runtime-31">
+WoT
+Runtime
+</a>
+<em class= "rfc2119">
+SHOULD
+</em>
+perform
+isolation
+of
+script
+instances
+and
+their
+data
+from
+each
+other
+in
+cases
+when
+scripts
+handle
+sensitive
+data.
+</span>
+<span class="rfc2119-assertion" id= "arch-security-consideration-isolation-tenants">
+Similarly,
+the
+<a href="#dfn-wot-runtime" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-runtime-32">
+WoT
+Runtime
+</a>
+implementation
+<em class="rfc2119">
+SHOULD
+</em>
+perform
+isolation
+of
+<a href= "#dfn-wot-runtime" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-runtime-33">
+WoT
+Runtime
+</a>
+instances
+and
+their
+data
+from
+each
+other
+if
+a
+WoT
+device
+has
+more
+than
+one
+tenant.
+</span>
+In
+practice,
+isolation
+of
+scripts
+and
+runtime
+instances
+from
+each
+other
+can
+be
+accomplished
+by
+running
+all
+instances
+in
+a
+"sandboxed"
+environment
+that
+controls
+its
+access
+to
+the
+rest
+of
+the
+environment.
+For
+more
+information
+see
+Sections
+<a href= "https://www.w3.org/TR/wot-security/#wot-servient-single-tenant">
+WoT
+Servient
+Single-Tenant
+</a>
+and
+<a href= "https://www.w3.org/TR/wot-security/#wot-servient-multi-tenant">
+WoT
+Servient
+Multi-Tenant
+</a>
+of
+the
+<em>
+WoT
+Security
+and
+Privacy
+Guidelines
+</em>
+specification
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href="#bib-wot-security" title= "Web of Things (WoT) Security and Privacy Guidelines">
+WOT-SECURITY
+</a>
+</cite>
+].
+</dd>
+</dl>
+</section>
+<section id="sec-security-consideration-device-direct-access">
+<div class="header-wrapper">
+<h4 id="x10-2-2-physical-device-direct-access-risk">
+<bdi class= "secno">
+10.2.2
+</bdi>
+Physical
+Device
+Direct
+Access
+Risk
+</h4>
+<a class="self-link" href= "#sec-security-consideration-device-direct-access" aria-label= "Permalink for Section 10.2.2">
+</a>
+</div>
+<p>
+In
+case
+a
+script
+is
+compromised
+or
+malfunctions
+the
+underlying
+physical
+device
+(and
+potentially
+surrounded
+environment)
+can
+be
+damaged
+if
+a
+script
+can
+use
+directly
+exposed
+native
+device
+interfaces.
+If
+such
+interfaces
+lack
+safety
+checks
+on
+their
+inputs,
+they
+might
+bring
+the
+underlying
+physical
+device
+(or
+environment)
+to
+an
+unsafe
+state.
+</p>
+<dl>
+<dt>
+Mitigation:
+</dt>
+<dd>
+<p>
+In
+order
+to
+reduce
+the
+damage
+to
+a
+physical
+WoT
+device
+in
+cases
+a
+script
+gets
+compromised,
+it
+is
+important
+to
+minimize
+the
+number
+of
+interfaces
+that
+are
+exposed
+or
+accessible
+to
+a
+particular
+script
+based
+on
+its
+functionality.
+<span class="rfc2119-assertion" id= "arch-security-consideration-avoid-direct">
+The
+<a href= "#dfn-wot-runtime" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-runtime-34">
+WoT
+Runtime
+</a>
+<em class= "rfc2119">
+SHOULD
+NOT
+</em>
+directly
+expose
+low-level
+device
+hardware
+interfaces
+to
+the
+script
+developers.
+</span>
+</p>
+<p>
+Hardware
+abstraction
+layers
+can
+provide
+an
+additional
+level
+of
+protection.
+Hardware
+abstraction
+layers
+are
+software
+components
+that
+mediate
+the
+interaction
+between
+the
+application
+and
+the
+hardware
+and
+can
+be
+as
+simple
+as
+a
+software
+library,
+although
+more
+sophisticated
+implementations
+may
+be
+implemented
+as
+drivers
+accessible
+through
+system
+calls
+or
+supported
+by
+hypervisors.
+The
+more
+sophisticated
+versions
+of
+hardware
+abstraction
+layers
+can
+prevent
+applications
+from
+bypassing
+them.
+<span class= "rfc2119-assertion" id="arch-security-consideration-use-hal">
+A
+<a href="#dfn-wot-runtime" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-runtime-35">
+WoT
+Runtime
+</a>
+implementation
+<em class="rfc2119">
+SHOULD
+</em>
+provide
+a
+hardware
+abstraction
+layer
+for
+accessing
+the
+low-level
+device
+hardware
+interfaces.
+</span>
+Hardware
+abstraction
+layers
+should
+refuse
+to
+execute
+commands
+that
+might
+put
+the
+device
+(or
+environment)
+to
+an
+unsafe
+state.
+Such
+"software
+interlocks"
+should
+not
+be
+the
+only
+mechanism
+preventing
+a
+system
+from
+entering
+an
+unsafe
+state.
+Ideally,
+multiple
+layered
+safety
+controls
+should
+be
+used,
+including
+both
+software
+and
+hardware
+interlocks.
+</p>
+</dd>
+</dl>
+</section>
+</section>
+<section id="sec-security-consideration-runtime-risks">
+<div class="header-wrapper">
+<h3 id="x10-3-wot-runtime-risks">
+<bdi class="secno">
+10.3
+</bdi>
+WoT
+Runtime
+Risks
+</h3>
+<a class="self-link" href= "#sec-security-consideration-runtime-risks" aria-label= "Permalink for Section 10.3">
+</a>
+</div>
+<section id="sec-security-consideration-update-provisioning">
+<div class="header-wrapper">
+<h4 id="x10-3-1-provisioning-and-update-security-risk">
+<bdi class= "secno">
+10.3.1
+</bdi>
+Provisioning
+and
+Update
+Security
+Risk
+</h4>
+<a class="self-link" href= "#sec-security-consideration-update-provisioning" aria-label= "Permalink for Section 10.3.1">
+</a>
+</div>
+<p>
+If
+the
+<a href="#dfn-wot-runtime" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-runtime-36">
+WoT
+Runtime
+</a>
+implementation
+supports
+post-manufacturing
+provisioning
+or
+updates
+of
+itself,
+scripts,
+or
+any
+related
+data
+(including
+security
+credentials),
+it
+can
+be
+a
+major
+attack
+vector.
+An
+attacker
+can
+try
+to
+modify
+any
+above
+described
+element
+during
+the
+update
+or
+provisioning
+process
+or
+simply
+provision
+attacker's
+code
+and
+data
+directly.
+</p>
+<dl>
+<dt>
+Mitigation:
+</dt>
+<dd>
+<span class="rfc2119-assertion" id= "arch-security-consideration-secure-update">
+Post-manufacturing
+provisioning
+or
+update
+of
+scripts,
+the
+<a href="#dfn-wot-runtime" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-runtime-37">
+WoT
+Runtime
+</a>
+itself
+or
+any
+related
+data
+<em class="rfc2119">
+SHOULD
+</em>
+be
+done
+in
+a
+secure
+fashion.
+</span>
+A
+set
+of
+recommendations
+for
+secure
+update
+and
+post-manufacturing
+provisioning
+can
+be
+found
+in
+the
+<em>
+WoT
+Security
+and
+Privacy
+Guidelines
+</em>
+specification
+[
+<cite>
+<a class= "bibref" data-link-type="biblio" href="#bib-wot-security" title= "Web of Things (WoT) Security and Privacy Guidelines">
+WOT-SECURITY
+</a>
+</cite>
+].
+</dd>
+</dl>
+</section>
+<section id="sec-security-consideration-credentials-storage">
+<div class="header-wrapper">
+<h4 id="x10-3-2-security-credentials-storage-risk">
+<bdi class= "secno">
+10.3.2
+</bdi>
+Security
+Credentials
+Storage
+Risk
+</h4>
+<a class="self-link" href= "#sec-security-consideration-credentials-storage" aria-label= "Permalink for Section 10.3.2">
+</a>
+</div>
+<p>
+Typically
+the
+<a href="#dfn-wot-runtime" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-runtime-38">
+WoT
+Runtime
+</a>
+needs
+to
+store
+the
+security
+credentials
+that
+are
+provisioned
+to
+a
+WoT
+device
+to
+operate
+in
+a
+network.
+If
+an
+attacker
+can
+compromise
+the
+confidentiality
+or
+integrity
+of
+these
+credentials,
+then
+it
+can
+obtain
+access
+to
+assets,
+impersonate
+other
+WoT
+Things,
+devices,
+or
+services,
+or
+launch
+Denial-Of-Service
+(DoS)
+attacks.
+</p>
+<dl>
+<dt>
+Mitigation:
+</dt>
+<dd>
+<span class="rfc2119-assertion" id= "arch-security-consideration-secure-cred-storage">
+The
+<a href= "#dfn-wot-runtime" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-runtime-39">
+WoT
+Runtime
+</a>
+<em class= "rfc2119">
+SHOULD
+</em>
+securely
+store
+any
+provisioned
+security
+credentials,
+guaranteeing
+their
+integrity
+and
+confidentiality.
+</span>
+<span class="rfc2119-assertion" id= "arch-security-consideration-secure-cred-isolation">
+In
+case
+there
+are
+more
+than
+one
+tenant
+on
+a
+single
+WoT-enabled
+device,
+a
+<a href= "#dfn-wot-runtime" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-runtime-40">
+WoT
+Runtime
+</a>
+implementation
+<em class="rfc2119">
+SHOULD
+</em>
+isolate
+each
+tenant's
+provisioned
+security
+credentials
+from
+other
+tenants.
+</span>
+<span class= "rfc2119-assertion" id= "arch-security-consideration-no-expose-cred">
+In
+order
+to
+minimize
+a
+risk
+that
+provisioned
+security
+credentials
+get
+compromised,
+the
+<a href="#dfn-wot-runtime" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-wot-runtime-41">
+WoT
+Runtime
+</a>
+implementation
+<em class="rfc2119">
+SHOULD
+NOT
+</em>
+expose
+any
+API
+for
+scripts
+to
+query
+provisioned
+security
+credentials.
+</span>
+<span class= "rfc2119-assertion" id= "arch-security-consideration-limit-cred-access">
+Such
+credentials
+(or
+even
+better,
+abstract
+operations
+that
+use
+them
+but
+do
+not
+expose
+them)
+<em class="rfc2119">
+SHOULD
+</em>
+only
+be
+accessible
+to
+the
+underlying
+protocol
+implementation
+that
+uses
+them.
+</span>
+</dd>
+</dl>
+</section>
+</section>
+<section id="sec-security-consideration-trusted-environment-risks">
+<div class="header-wrapper">
+<h3 id="x10-4-trusted-environment-risks">
+<bdi class= "secno">
+10.4
+</bdi>
+Trusted
+Environment
+Risks
+</h3>
+<a class="self-link" href= "#sec-security-consideration-trusted-environment-risks" aria-label= "Permalink for Section 10.4">
+</a>
+</div>
+<p>
+In
+section
+<a href="#sec-common-deployment-patterns" class= "sec-ref">
+<bdi class="secno">
+5.
+</bdi>
+Common
+Deployment
+Patterns
+</a>
+several
+usage
+scenarios
+are
+presented
+that
+include
+the
+concept
+of
+a
+<a href="#dfn-trusted-environment" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-trusted-environment-2">
+Trusted
+Environment
+</a>
+and
+a
+security
+boundary.
+Entities
+that
+are
+members
+of
+a
+<a href="#dfn-trusted-environment" class="internalDFN" data-link-type="dfn" id="ref-for-dfn-trusted-environment-3">
+Trusted
+Environment
+</a>
+all
+share
+access
+to
+a
+common
+set
+of
+resources
+(such
+as
+a
+local
+network)
+and
+are
+implicitly
+granted
+certain
+access
+rights
+to
+each
+other.
+A
+common
+example
+would
+be
+a
+WiFi
+LAN
+in
+the
+home
+where
+access
+to
+the
+WEP
+password
+allows
+devices
+to
+communicate
+with
+each
+other
+without
+any
+further
+access
+controls.
+Allowing
+implicit
+access
+rights
+like
+this
+and
+using
+a
+single
+shared
+secret
+for
+a
+large
+number
+of
+entities
+means
+that
+a
+single
+malicious
+actor
+with
+access
+to
+the
+<a href="#dfn-trusted-environment" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-trusted-environment-4">
+Trusted
+Environment
+</a>
+can
+cause
+significant
+damage.
+</p>
+<p>
+One
+common
+IoT
+situation
+is
+the
+use
+of
+an
+HTTP/HTML
+browser
+to
+access
+locally
+hosted
+web
+services
+in
+a
+home
+environment.
+Such
+locally
+hosted
+web
+services
+may
+not
+have
+a
+publicly
+visible
+URL
+and
+so
+are
+not
+able
+to
+participate
+in
+the
+CA
+system
+expected
+by
+browsers
+to
+enable
+use
+of
+HTTP/TLS
+(HTTPS).
+It
+is
+often
+the
+case
+in
+this
+situation
+that
+plain
+HTTP
+is
+used
+and
+the
+only
+security
+protecting
+the
+communication
+is
+network
+encryption,
+for
+example
+WEP,
+which
+is
+relatively
+weak.
+</p>
+<dl>
+<dt>
+Mitigation:
+</dt>
+<dd>
+<span class="rfc2119-assertion" id= "arch-security-consideration-limit-trust">
+Trust
+relationships
+<em class="rfc2119">
+SHOULD
+</em>
+be
+as
+restricted
+as
+possible,
+ideally
+pairwise
+and
+limited
+to
+precisely
+the
+access
+required.
+</span>
+As
+noted,
+in
+some
+situations
+this
+is
+difficult
+to
+manage
+and
+implicit
+access
+such
+as
+described
+is
+used,
+and
+may
+even
+be
+assumed
+by
+certain
+entities,
+such
+as
+browsers.
+<span class= "rfc2119-assertion" id= "arch-security-consideration-segmented-network">
+In
+the
+case
+of
+implicit
+access
+control
+via
+access
+to
+a
+common
+network
+a
+segmented
+network
+<em class="rfc2119">
+SHOULD
+</em>
+be
+used.
+</span>
+For
+example,
+in
+the
+home
+environment,
+a
+separate
+network
+can
+be
+used
+for
+IoT
+devices.
+In
+commercial
+and
+industrial
+environments,
+explicit
+installation
+of
+certificates
+should
+be
+used
+to
+allow
+browsers
+to
+access
+local
+services
+while
+using
+TLS.
+Certificates
+support
+secure
+authentication
+and
+are
+required
+to
+enable
+TLS.
+Once
+TLS
+is
+enabled
+other
+security
+mechanisms
+that
+assume
+secure
+transport,
+such
+as
+API
+keys
+or
+passwords,
+can
+be
+used
+to
+provide
+fine-grained
+access
+control.
+Note
+that
+using
+a
+single
+key
+for
+a
+large
+number
+of
+services
+is
+equivalent
+to
+the
+"implicit
+access"
+situation
+above.
+</dd>
+</dl>
+</section>
+<section id="sec-security-consideration-secure-transport">
+<div class="header-wrapper">
+<h3 id="x10-5-secure-transport">
+<bdi class="secno">
+10.5
+</bdi>
+Secure
+Transport
+</h3>
+<a class="self-link" href= "#sec-security-consideration-secure-transport" aria-label= "Permalink for Section 10.5">
+</a>
+</div>
+<p>
+As
+noted
+in
+<a href= "#sec-security-consideration-trusted-environment-risks" class= "sec-ref">
+<bdi class="secno">
+10.4
+</bdi>
+Trusted
+Environment
+Risks
+</a>,
+there
+are
+situations
+in
+which
+secure
+transports,
+such
+as
+TLS,
+are
+not
+feasible
+or
+are
+difficult
+to
+set
+up,
+such
+as
+on
+a
+local
+LAN
+within
+a
+home.
+Unfortunately,
+generally
+access
+control
+mechanisms
+in
+HTTP
+are
+designed
+to
+be
+used
+with
+secure
+transport
+and
+can
+be
+easily
+bypassed
+without
+it.
+In
+particular,
+it
+is
+relatively
+easy
+to
+capture
+passwords
+and
+tokens
+from
+unencrypted
+protocol
+interactions
+which
+can
+be
+intercepted
+by
+a
+third
+party.
+Also,
+man-in-the-middle
+attacks
+can
+be
+easily
+implemented
+without
+TLS
+providing
+server
+authentication.
+</p>
+<dl>
+<dt>
+Mitigation:
+</dt>
+<dd>
+<p>
+Because
+of
+the
+practical
+difficulties
+in
+setting
+up
+secure
+transport
+in
+all
+situations,
+we
+cannot
+make
+a
+blanket
+assertion
+that
+it
+is
+always
+required.
+Instead
+we
+provide
+a
+set
+of
+requirements
+for
+different
+use
+cases:
+</p>
+<dl>
+<dt>
+Public
+Networks:
+</dt>
+<dd>
+<span class="rfc2119-assertion" id= "arch-security-consideration-tls-mandatory-pub">
+When
+a
+Thing
+is
+made
+available
+on
+the
+public
+internet
+so
+it
+can
+be
+accessed
+by
+anyone,
+from
+anywhere,
+then
+it
+<em class="rfc2119">
+MUST
+</em>
+be
+protected
+by
+secure
+transport
+such
+as
+TLS
+or
+DTLS.
+</span>
+A
+Thing
+available
+on
+the
+public
+internet
+will
+have
+a
+public
+URL
+and
+so
+normal
+CA
+mechanisms
+to
+provide
+certificates
+are
+available.
+This
+should
+be
+done
+even
+if
+there
+are
+no
+access
+controls
+on
+the
+endpoint,
+for
+example
+when
+providing
+a
+publicly
+accessible
+service,
+because
+secure
+transport
+also
+protects
+the
+privacy
+of
+requesters
+(for
+example,
+the
+content
+of
+queries).
+</dd>
+<dt>
+Private
+Networks:
+</dt>
+<dd>
+<span class="rfc2119-assertion" id= "arch-security-consideration-tls-recommended-priv">
+When
+a
+Thing
+is
+made
+available
+on
+a
+private
+network
+then
+it
+<em class= "rfc2119">
+SHOULD
+</em>
+be
+protected
+by
+secure
+transport
+such
+as
+TLS
+or
+DTLS.
+</span>
+The
+risk
+increases
+with
+the
+sensitivity
+of
+the
+data
+being
+protected,
+the
+potential
+for
+damage,
+and
+with
+the
+number
+of
+people
+given
+access
+to
+the
+private
+network.
+Secure
+transport
+is
+a
+higher
+priority
+in
+higher
+risk
+situations
+such
+as
+a
+factory
+network;
+in
+such
+cases,
+it
+is
+also
+more
+practical
+to
+install
+pre-shared
+keys.
+In
+low-risk
+situations,
+the
+following
+is
+permissible:
+<span class="rfc2119-assertion" id= "arch-security-consideration-tls-optional-on-lan">
+Private
+networks
+such
+as
+a
+LAN,
+protected
+by
+a
+firewall,
+<em class= "rfc2119">
+MAY
+</em>
+use
+the
+<a href= "#sec-security-consideration-trusted-environment-risks">
+Trusted
+Environment
+</a>
+approach
+of
+depending
+on
+network
+security
+only.
+</span>
+This
+is
+not
+generally
+recommended
+but
+may
+be
+necessary
+for
+practical
+reasons.
+Please
+see
+the
+referenced
+security
+consideration
+for
+additional
+risks
+and
+mitigations
+with
+this
+approach.
+</dd>
+<dt>
+Brownfield
+Devices:
+</dt>
+<dd>
+WoT
+is
+descriptive
+and
+an
+accurate
+description
+of
+existing
+"brownfield"
+devices
+may
+reveal
+they
+are
+not
+secure.
+For
+example,
+a
+specific
+device
+may
+use
+HTTP
+without
+TLS,
+which
+is
+not
+secure
+even
+if
+it
+uses
+access
+controls
+such
+as
+a
+password.
+It
+is
+often
+not
+possible
+to
+upgrade
+such
+devices
+to
+support
+stronger
+security.
+In
+these
+cases,
+the
+above
+two
+mitigations
+still
+apply.
+If
+exposed
+on
+a
+private
+network,
+the
+<a href= "#sec-security-consideration-trusted-environment-risks">
+Trusted
+Environment
+</a>
+approach
+should
+be
+used,
+with
+access
+limited
+as
+much
+as
+possible.
+If
+it
+is
+desired
+to
+expose
+such
+a
+device
+on
+the
+public
+internet,
+additional
+steps
+should
+be
+taken
+the
+enhance
+its
+security.
+In
+particular,
+a
+proxy
+can
+be
+used
+to
+ensure
+that
+communications
+over
+the
+public
+network
+use
+secure
+transport.
+A
+proxy
+can
+also
+be
+used
+to
+provide
+access
+controls.
+</dd>
+</dl>
+<p>
+<span class="rfc2119-assertion" id= "arch-security-consideration-tls-1-3">
+When
+secure
+transport
+over
+TCP
+is
+appropriate,
+then
+at
+least
+TLS
+1.3
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href="#bib-rfc8446" title= "The Transport Layer Security (TLS) Protocol Version 1.3">
+RFC8446
+</a>
+</cite>
+]
+<em class="rfc2119">
+SHOULD
+</em>
+be
+used.
+</span>
+<span class= "rfc2119-assertion" id="arch-security-consideration-tls-1-2">
+If
+TLS
+1.3
+cannot
+be
+used
+for
+compatibility
+reasons
+but
+secure
+transport
+over
+TCP
+is
+appropriate,
+TLS
+1.2
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href="#bib-rfc5246" title= "The Transport Layer Security (TLS) Protocol Version 1.2">
+RFC5246
+</a>
+</cite>
+]
+<em class="rfc2119">
+MAY
+</em>
+be
+used.
+</span>
+When
+secure
+transport
+over
+UDP
+is
+appropriate,
+then
+at
+least
+DTLS
+1.3
+[
+<cite>
+<a class= "bibref" data-link-type="biblio" href="#bib-rfc9147" title= "The Datagram Transport Layer Security (DTLS) Protocol Version 1.3">
+RFC9147
+</a>
+</cite>
+]
+is
+recommended,
+if
+possible.
+<span class="rfc2119-assertion" id= "arch-security-consideration-dtls-1-2">
+If
+DTLS
+1.3
+cannot
+be
+used
+for
+compatibility
+reasons
+but
+secure
+transport
+over
+UDP
+is
+appropriate,
+then
+DTLS
+1.2
+[
+<cite>
+<a class="bibref" data-link-type= "biblio" href="#bib-rfc6347" title= "Datagram Transport Layer Security Version 1.2">
+RFC6347
+</a>
+</cite>
+]
+<em class="rfc2119">
+MAY
+</em>
+be
+used.
+</span>
+<span class= "rfc2119-assertion" id= "arch-security-consideration-no-earlier-tls-or-dtls">
+Versions
+of
+DTLS
+or
+TLS
+earlier
+than
+1.2
+<em class="rfc2119">
+MUST
+NOT
+</em>
+be
+used
+for
+new
+development.
+</span>
+Existing
+Things
+using
+earlier
+versions
+of
+TLS
+or
+DTLS
+can
+be
+described
+by
+WoT
+metadata
+(e.g.
+Thing
+Descriptions)
+but
+should
+be
+considered
+insecure.
+</p>
+<p>
+Additional
+considerations
+apply
+if
+a
+Thing
+can
+reveal
+<a href= "#dfn-personally-identifiable-information" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-personally-identifiable-information-2">
+Personally
+Identifiable
+Information
+</a>
+(PII).
+See
+<a href= "#arch-privacy-consideration-access-controls" class= "sec-ref">
+<bdi class="secno">
+11.2
+</bdi>
+Access
+to
+Personally
+Identifiable
+Information
+</a>.
+</p>
+</dd>
+</dl>
+</section>
+</section>
+<section id="sec-privacy-considerations">
+<div class="header-wrapper">
+<h2 id="x11-privacy-considerations">
+<bdi class="secno">
+11.
+</bdi>
+Privacy
+Considerations
+</h2>
+<a class="self-link" href="#sec-privacy-considerations" aria-label= "Permalink for Section 11.">
+</a>
+</div>
+<p>
+Privacy
+is
+a
+cross-cutting
+issue
+that
+needs
+to
+be
+considered
+in
+all
+<a href="#sec-building-blocks">
+WoT
+building
+blocks
+</a>
+and
+WoT
+implementations.
+This
+chapter
+summarizes
+some
+general
+issues
+and
+guidelines
+to
+help
+preserve
+the
+privacy
+of
+concrete
+WoT
+implementations.
+However,
+these
+are
+only
+general
+guidelines
+and
+an
+abstract
+architecture
+such
+as
+described
+in
+this
+document
+cannot,
+itself,
+guarantee
+privacy.
+Instead
+the
+details
+of
+a
+concrete
+implementation
+need
+to
+be
+considered.
+For
+a
+more
+detailed
+and
+complete
+analysis
+of
+privacy
+(and
+security)
+issues,
+see
+the
+<em>
+WoT
+Security
+and
+Privacy
+Guidelines
+</em>
+specification
+[
+<cite>
+<a class= "bibref" data-link-type="biblio" href="#bib-wot-security" title= "Web of Things (WoT) Security and Privacy Guidelines">
+WOT-SECURITY
+</a>
+</cite>
+].
+</p>
+<section id="sec-privacy-consideration-td-risks">
+<div class="header-wrapper">
+<h3 id="x11-1-wot-thing-description-risks">
+<bdi class= "secno">
+11.1
+</bdi>
+WoT
+Thing
+Description
+Risks
+</h3>
+<a class="self-link" href="#sec-privacy-consideration-td-risks" aria-label="Permalink for Section 11.1">
+</a>
+</div>
+<p>
+The
+metadata
+contained
+in
+a
+<a href="#dfn-wot-thing-description" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-thing-description-25">
+WoT
+Thing
+Description
+</a>
+(TD)
+is
+potentially
+sensitive,
+and
+even
+if
+it
+does
+not
+explicitly
+contain
+<a href="#dfn-personally-identifiable-information" class= "internalDFN" data-link-type="dfn" id= "ref-for-dfn-personally-identifiable-information-3">
+Personally
+Identifiable
+Information
+</a>
+(PII)
+it
+may
+be
+possible
+to
+infer
+PII
+from
+it.
+As
+a
+best
+practice,
+TDs
+should
+be
+used
+together
+with
+appropriate
+integrity
+protection
+mechanisms
+and
+access
+control
+policies,
+with
+the
+goal
+of
+providing
+it
+only
+to
+authorized
+users.
+In
+general,
+many
+of
+the
+<a href= "#sec-security-considerations">
+Security
+Considerations
+</a>
+discussed
+in
+the
+previous
+section
+can
+also
+be
+seen
+as
+privacy
+risks,
+when
+they
+relate
+the
+undesired
+an
+unauthorized
+disclosure
+of
+information.
+</p>
+<p>
+Please
+refer
+to
+the
+Privacy
+Considerations
+sections
+of
+the
+WoT
+Thing
+Description
+specification
+for
+additional
+details
+and
+discussion
+of
+these
+points.
+</p>
+<section id="sec-privacy-consideration-td-pii">
+<div class="header-wrapper">
+<h4 id= "x11-1-1-thing-description-personally-identifiable-information-risk">
+<bdi class="secno">
+11.1.1
+</bdi>
+Thing
+Description
+Personally
+Identifiable
+Information
+Risk
+</h4>
+<a class="self-link" href="#sec-privacy-consideration-td-pii" aria-label="Permalink for Section 11.1.1">
+</a>
+</div>
+<p>
+Thing
+descriptions
+can
+potentially
+contain
+<a href= "#dfn-personally-identifiable-information" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-personally-identifiable-information-4">
+Personally
+Identifiable
+Information
+</a>
+(PII)
+of
+various
+types.
+Even
+if
+it
+is
+not
+explicit,
+a
+TD
+and
+its
+association
+with
+an
+identifiable
+person
+can
+be
+used
+to
+infer
+information
+about
+that
+person.
+For
+example,
+the
+association
+of
+fingerprintable
+TDs
+exposed
+by
+mobile
+devices
+whose
+location
+can
+be
+determined
+can
+be
+a
+tracking
+risk.
+Even
+if
+a
+particular
+device
+instance
+cannot
+be
+identified,
+the
+type
+of
+device
+represented
+by
+a
+TD,
+when
+associated
+with
+a
+person,
+may
+constitute
+personal
+information.
+For
+example,
+a
+medical
+device
+may
+be
+used
+to
+infer
+that
+the
+user
+has
+a
+medical
+condition.
+</p>
+<p>
+Generally,
+<a href="#dfn-personally-identifiable-information" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-personally-identifiable-information-5">
+Personally
+Identifiable
+Information
+</a>
+in
+a
+TD
+should
+be
+limited
+as
+much
+as
+possible.
+In
+some
+cases,
+however,
+it
+cannot
+be
+avoided.
+The
+potential
+presence
+of
+both
+direct
+and
+inferencable
+PII
+in
+a
+TD
+means
+that
+TD
+as
+a
+whole
+should
+be
+treated
+like
+other
+forms
+of
+PII.
+They
+should
+be
+stored
+and
+transmitted
+in
+a
+secure
+fashion,
+should
+only
+be
+provided
+to
+authorized
+users,
+should
+only
+be
+cached
+for
+limited
+times,
+should
+be
+deleted
+upon
+request,
+should
+only
+be
+used
+for
+the
+purpose
+for
+which
+they
+were
+provided
+with
+user
+consent,
+and
+they
+should
+otherwise
+satisfy
+all
+requirements
+(including
+any
+legal
+requirements)
+for
+the
+use
+of
+PII.
+</p>
+<dl>
+<dt>
+Mitigation:
+</dt>
+<dd>
+<span class="rfc2119-assertion" id= "arch-privacy-consideration-min-explicit-pii">
+Storage
+of
+explicit
+PII
+in
+TDs
+<em class="rfc2119">
+SHOULD
+</em>
+be
+minimized
+as
+much
+as
+possible.
+</span>
+Even
+without
+explicit
+PII
+in
+TDs,
+a
+tracking
+and
+identification
+privacy
+risk
+may
+exist.
+<span class= "rfc2119-assertion" id= "arch-privacy-consideration-explicit-pii">
+TDs
+that
+can
+be
+associated
+with
+a
+person
+<em class="rfc2119">
+SHOULD
+</em>
+generally
+be
+treated
+as
+if
+they
+contained
+PII
+and
+subject
+to
+the
+same
+management
+policies
+as
+other
+PII,
+even
+if
+they
+do
+not
+explicitly
+contain
+it.
+</span>
+<span class="rfc2119-assertion" id= "arch-privacy-consideration-dist-td-auth">
+Distribution
+mechanisms
+for
+TDs
+<em class="rfc2119">
+SHOULD
+</em>
+ensure
+they
+are
+only
+provided
+to
+authorized
+Consumers.
+</span>
+Note
+that
+the
+<a href= "#dfn-wot-discovery" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-discovery-16">
+WoT
+Discovery
+</a>
+mechanism
+is
+designed
+to
+address
+these
+specific
+issues,
+as
+long
+as
+it
+is
+used
+with
+authentication
+and
+access
+controls
+on
+exploration
+services.
+As
+a
+general
+matter
+of
+policy,
+unnecessary
+information
+should
+not
+be
+exposed
+in
+TDs
+whenever
+possible.
+For
+example,
+explicit
+type
+and
+instance
+identifying
+information
+in
+TDs
+should
+only
+be
+included
+if
+it
+is
+needed
+by
+the
+use
+case.
+Even
+if
+required
+by
+the
+use
+case,
+to
+minimize
+tracking
+risks,
+distributed
+and
+limited-scope
+identifiers
+should
+be
+used
+whenever
+possible
+rather
+than
+globally
+unique
+identifiers.
+Other
+forms
+of
+information,
+such
+as
+human-readable
+descriptions,
+may
+also
+be
+omitted
+in
+some
+use
+cases
+to
+reduce
+fingerprinting
+risks.
+</dd>
+</dl>
+</section>
+</section>
+<section id="arch-privacy-consideration-access-controls">
+<div class="header-wrapper">
+<h3 id="x11-2-access-to-personally-identifiable-information">
+<bdi class="secno">
+11.2
+</bdi>
+Access
+to
+Personally
+Identifiable
+Information
+</h3>
+<a class="self-link" href= "#arch-privacy-consideration-access-controls" aria-label= "Permalink for Section 11.2">
+</a>
+</div>
+<p>
+In
+addition
+to
+the
+risks
+of
+revealing
+<a href= "#dfn-personally-identifiable-information" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-personally-identifiable-information-6">
+Personally
+Identifiable
+Information
+</a>
+(PII)
+through
+metadata
+discussed
+in
+<a href="#sec-privacy-consideration-td-pii" class= "sec-ref">
+<bdi class="secno">
+11.1.1
+</bdi>
+Thing
+Description
+Personally
+Identifiable
+Information
+Risk
+</a>,
+the
+data
+returned
+by
+Things
+can
+itself
+be
+sensitive.
+For
+example,
+a
+Thing
+could
+be
+monitoring
+the
+location
+or
+health
+of
+a
+specific
+person.
+Information
+associated
+with
+a
+person
+should
+be
+treated
+as
+PII
+even
+if
+it
+is
+not
+immediately
+obvious
+that
+it
+is
+sensitive,
+since
+it
+could
+be
+combined
+with
+other
+information
+to
+reveal
+sensitive
+information.
+</p>
+<dl>
+<dt>
+Mitigation:
+</dt>
+<dd>
+<span class="rfc2119-assertion" id= "arch-privacy-consideration-access-control-mandatory-person">
+Things
+returning
+data
+or
+metadata
+(such
+as
+TDs)
+associated
+with
+a
+person
+<em class="rfc2119">
+SHOULD
+</em>
+use
+some
+form
+of
+access
+control.
+</span>
+A
+special
+case
+of
+this
+is
+a
+<a href= "#dfn-wot-thing-description-directory" class="internalDFN" data-link-type="dfn" id= "ref-for-dfn-wot-thing-description-directory-21">
+Thing
+Description
+Directory
+</a>,
+as
+described
+in
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href="#bib-wot-discovery" title= "Web of Things (WoT) Discovery">
+WOT-DISCOVERY
+</a>
+</cite>
+],
+which
+is
+a
+Thing
+that
+returns
+Thing
+Descriptions
+as
+data.
+Such
+directory
+services
+are
+included
+in
+the
+above
+statement
+and
+should
+use
+access
+control
+if
+the
+TDs
+describe
+Things
+associated
+with
+identifiable
+people.
+In
+the
+case
+of
+services
+returning
+Thing
+Descriptions,
+the
+following
+also
+applies:
+<span class="rfc2119-assertion" id= "arch-privacy-consideration-id-access-control-mandatory-immutable">
+Services
+returning
+Thing
+Descriptions
+with
+immutable
+IDs
+<em class= "rfc2119">
+SHOULD
+</em>
+use
+some
+form
+of
+access
+control.
+</span>
+Following
+the
+principle
+that
+Thing
+Descriptions
+describing
+Things
+associated
+with
+specific
+persons
+should
+be
+treated
+as
+PII,
+even
+if
+they
+do
+not
+explicitly
+contain
+it,
+this
+implies
+that
+directories
+providing
+such
+TDs
+should
+use
+access
+control.
+Generally
+speaking,
+the
+only
+exceptions
+should
+be
+cases
+where
+access
+is
+controlled
+by
+another
+mechanism
+not
+described
+in
+the
+TD
+itself,
+such
+as
+a
+segmented
+network.
+Again
+it
+should
+also
+be
+noted
+that
+access
+controls
+are
+generally
+only
+effective
+when
+secure
+transport
+is
+also
+used;
+see
+<a href="#sec-security-consideration-secure-transport" class="sec-ref">
+<bdi class="secno">
+10.5
+</bdi>
+Secure
+Transport
+</a>.
+Use
+of
+access
+controls
+without
+secure
+transport,
+at
+best,
+only
+discourages
+casual
+access
+by
+unauthorized
+parties.
+</dd>
+</dl>
+</section>
+</section>
+<section id="sec-accessibility-considerations" class="informative">
+<div class="header-wrapper">
+<h2 id="x12-accessibility-considerations">
+<bdi class= "secno">
+12.
+</bdi>
+Accessibility
+Considerations
+</h2>
+<a class="self-link" href="#sec-accessibility-considerations" aria-label="Permalink for Section 12.">
+</a>
+</div>
+<p>
+<em>
+This
+section
+is
+non-normative.
+</em>
+</p>
+<p>
+IoT
+generally
+and
+WoT
+in
+particular
+provide
+both
+opportunties
+and
+challenges
+for
+accessibilty.
+On
+the
+one
+hand,
+network
+access
+to
+internet-enabled
+devices'
+functionality
+makes
+it
+possible
+to
+build
+alternative
+interfaces
+to
+that
+functionality,
+both
+web-based
+and
+physical,
+that
+are
+not
+limited
+by
+the
+devices'
+own
+hardware.
+Such
+interfaces
+can
+and
+should
+follow
+best
+practices
+for
+accessibility.
+On
+the
+other
+hand,
+IoT
+devices
+are
+diverse,
+are
+often
+cost
+and
+space
+limited,
+and
+situations
+where
+they
+do
+need
+to
+rely
+on
+their
+own
+hardware
+for
+interfacing,
+such
+as
+during
+onboarding
+before
+a
+network
+connection
+is
+established,
+can
+be
+challenging
+to
+make
+accessible.
+</p>
+<p>
+There
+are
+two
+situations
+to
+consider
+for
+WoT
+regarding
+accessibility:
+greenfield
+devices
+designed
+from
+the
+beginning
+to
+be
+used
+with
+WoT,
+and
+brownfield
+devices
+where
+WoT
+is
+used
+only
+to
+describe
+an
+existing
+system.
+</p>
+<p>
+A
+number
+of
+use
+cases
+that
+relate
+to
+accessibilty
+are
+covered
+in
+The
+<em>
+WoT
+Use
+Cases
+and
+Requirements
+</em>
+document
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-wot-use-cases-requirements" title= "Web of Things (WoT) Use Cases and Requirements">
+WOT-USE-CASES-REQUIREMENTS
+</a>
+</cite>
+].
+</p>
+<section id="sec-accessibility-considerations-greenfield">
+<div class="header-wrapper">
+<h3 id="x12-1-greenfield-wot-systems">
+<bdi class="secno">
+12.1
+</bdi>
+Greenfield
+WoT
+Systems
+</h3>
+<a class="self-link" href= "#sec-accessibility-considerations-greenfield" aria-label= "Permalink for Section 12.1">
+</a>
+</div>
+<p>
+Ideally,
+accessibility
+should
+be
+thought
+of
+from
+the
+beginning
+of
+the
+development
+of
+a
+component
+in
+any
+greenfield
+WoT
+system.
+If
+the
+component's
+hardware
+has
+its
+own
+display
+or
+other
+form
+of
+physical
+user
+interface,
+this
+must
+be
+as
+accessible
+as
+possible.
+If
+it
+cannot
+be
+made
+accessible
+(for
+example,
+due
+to
+screen
+size
+limitations),
+then
+equivalent
+functionality
+should
+be
+made
+available
+over
+the
+network
+so
+an
+accessible
+interface
+(such
+as
+a
+web
+or
+voice
+interface)
+can
+be
+used
+instead.
+When
+the
+component
+is
+accessed
+over
+the
+network,
+provisions
+must
+be
+made
+for
+accessible
+web
+interfaces
+whether
+hosted
+directly
+on
+the
+device
+or
+provided
+by
+another
+component
+(such
+as
+a
+dashboard).
+Situations
+where
+the
+on-board
+hardware
+is
+the
+only
+option
+for
+interfaces,
+such
+as
+during
+onboarding,
+should
+be
+carefully
+designed
+to
+be
+made
+as
+accessible
+as
+possible.
+</p>
+<ul>
+<li>
+For
+web-based
+user
+interfaces,
+relevant
+guidance
+on
+accessibility
+can
+be
+found
+in
+<abbr title= "World Wide Web Consortium">
+W3C
+</abbr>
+Web
+Content
+Accessibility
+Guidelines
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-wcag22" title= "Web Content Accessibility Guidelines (WCAG) 2.2">
+WCAG22
+</a>
+</cite>
+].
+</li>
+<li>
+More
+generally,
+EN
+301
+549
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href="#bib-etsi-en-301-549" title= "ETSI EN 301 549 V2.1.2 (2018-08): Accessibility requirements for ICT products and services">
+etsi-en-301-549
+</a>
+</cite>
+]
+provides
+guidelines
+for
+hardware
+and
+other
+user
+interfaces,
+especially
+for
+software/firmware
+running
+on
+"closed
+functionality"
+devices.
+</li>
+</ul>
+<p>
+In
+general,
+a
+Thing
+should
+always
+have
+at
+least
+one
+user
+interface
+(either
+direct
+or
+network-based)
+that
+is
+fully
+accessible
+according
+to
+WCAG
+and
+EN
+301
+549.
+Accessibility
+must
+be
+applied
+to
+the
+interfaces
+made
+available
+for
+all
+types
+of
+users:
+manufacturers,
+installers,
+device
+owners,
+end
+users.
+</p>
+<p>
+The
+accessibility
+status
+of
+the
+user
+interfaces
+for
+a
+Thing
+should
+be
+declared
+in
+the
+Thing’s
+metadata,
+so
+that
+users
+can
+pick
+the
+user
+interface
+that
+is
+most
+appropriate
+for
+them.
+If
+the
+Thing
+has
+a
+web
+interface,
+existing
+mechanisms
+to
+describe
+web
+interfaces
+should
+be
+used.
+To
+better
+support
+the
+connection
+between
+the
+web
+and
+physical
+interfaces,
+affordances
+described
+in
+a
+WoT
+Thing
+Description
+should
+be
+annotated
+in
+such
+a
+way
+that
+their
+relation
+to
+the
+physical
+interface
+on
+the
+device
+can
+be
+understood.
+</p>
+<p>
+Components
+that
+do
+not
+directly
+offer
+a
+user
+interface
+must
+still
+support
+accessibility
+by
+providing
+suitable
+data
+and
+functions.
+For
+example,
+developers
+of
+public
+Things
+(e.g.
+a
+ticket
+machine
+or
+an
+ATM)
+should
+consider
+a
+locator
+function
+by
+which
+a
+user
+can
+physically
+identify
+and
+locate
+the
+Thing
+by
+auditory,
+visual
+or
+other
+signaling.
+</p>
+</section>
+<section id="sec-accessibility-considerations-brownfield">
+<div class="header-wrapper">
+<h3 id="x12-2-brownfield-wot-systems">
+<bdi class="secno">
+12.2
+</bdi>
+Brownfield
+WoT
+Systems
+</h3>
+<a class="self-link" href= "#sec-accessibility-considerations-brownfield" aria-label= "Permalink for Section 12.2">
+</a>
+</div>
+<p>
+Brownfield
+applications
+of
+WoT
+cover
+situations
+where
+WoT
+metadata
+is
+used
+to
+describe
+an
+existing
+device,
+but
+WoT
+was
+not
+considered
+during
+its
+design.
+In
+this
+case
+many
+of
+the
+above
+provisions
+still
+apply.
+For
+example,
+a
+web
+interface
+provided
+by
+another
+system
+to
+monitor
+or
+control
+the
+device
+should
+follow
+the
+guidelines
+in
+WCAG,
+and
+the
+Thing
+Description
+should
+annotate
+affordances
+appropriately.
+If
+a
+device's
+own
+physical
+interface
+provides
+an
+accessibility
+challenge,
+there
+is
+the
+potential
+to
+overcome
+it
+with
+an
+alternative
+interface
+based
+on
+its
+network
+affordances.
+</p>
+</section>
+</section>
+<section id="changes" class="appendix">
+<div class="header-wrapper">
+<h2 id="a-recent-specification-changes">
+<bdi class="secno">
+A.
+</bdi>
+Recent
+Specification
+Changes
+</h2>
+<a class="self-link" href="#changes" aria-label= "Permalink for Appendix A.">
+</a>
+</div>
+<section id="changes-from-11-july-2023-proposed-recommendation">
+<div class="header-wrapper">
+<h3 id="changes-from-pr">
+<bdi class="secno">
+A.1
+</bdi>
+Changes
+from
+11
+July
+2023
+Proposed
+Recommendation
+</h3>
+<a class="self-link" href="#changes-from-pr" aria-label= "Permalink for Appendix A.1">
+</a>
+</div>
+<ul>
+<li>
+No
+normative
+changes
+from
+Proposed
+Recommendation.
+</li>
+<li>
+Add
+errata
+link.
+</li>
+<li>
+Update
+former
+editor's
+organization
+name.
+</li>
+<li>
+Update
+process
+link
+to
+3
+November
+2023.
+</li>
+<li>
+Update
+acknowledgements.
+</li>
+<li>
+Update
+references
+to
+IEC-FOTF
+document,
+WCAG
+2.2
+document,
+and
+other
+WoT
+documents.
+</li>
+<li>
+<a href= "https://services.w3.org/htmldiff?doc1=https%3A%2F%2Fwww.w3.org%2FTR%2F2023%2FPR-wot-architecture11-20230711%2F&amp;doc2=https%3A%2F%2Fraw.githubusercontent.com%2Fw3c%2Fwot-architecture%2Fmain%2Fpublication%2Fver11%2F5-rec%2FOverview.html">
+HTML
+Diff
+</a>
+</li>
+</ul>
+</section>
+<section id= "changes-from-19-january-2023-candidate-recommendation">
+<div class="header-wrapper">
+<h3 id="changes-from-cr">
+<bdi class="secno">
+A.2
+</bdi>
+Changes
+from
+19
+January
+2023
+Candidate
+Recommendation
+</h3>
+<a class="self-link" href="#changes-from-cr" aria-label= "Permalink for Appendix A.2">
+</a>
+</div>
+<ul>
+<li>
+No
+normative
+changes
+from
+Candidate
+Recommendation.
+</li>
+<li>
+At-risk
+assertions
+that
+did
+not
+receive
+sufficient
+implementations
+were
+removed
+or
+converted
+to
+informative
+statements.
+</li>
+<li>
+<a href= "https://w3c.github.io/wot-architecture/publication/ver11/4-pr/diff.html">
+HTML
+Diff
+</a>
+</li>
+</ul>
+</section>
+<section id="changes-from-the-wd-published-september-7-2022">
+<div class="header-wrapper">
+<h3 id="changes-from-wd-2022-09-07">
+<bdi class="secno">
+A.3
+</bdi>
+Changes
+from
+the
+WD
+published
+September
+7,
+2022
+</h3>
+<a class="self-link" href="#changes-from-wd-2022-09-07" aria-label= "Permalink for Appendix A.3">
+</a>
+</div>
+<ul>
+<li>
+Modify
+<a href="#sec-building-blocks">
+Section
+7,
+WoT
+Building
+Blocks
+</a>
+so
+that
+it
+is
+informative.
+</li>
+<li>
+Add
+terminology
+entries
+for
+Profile,
+System,
+and
+Directory.
+</li>
+<li>
+Updates
+to
+affiliation
+of
+Matthias
+Kovatsch
+(as
+a
+former
+editor).
+</li>
+<li>
+Add/update
+references
+to
+the
+WoT
+Use
+Cases
+and
+Requirements
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-wot-use-cases-requirements" title= "Web of Things (WoT) Use Cases and Requirements">
+WOT-USE-CASES-REQUIREMENTS
+</a>
+</cite>
+]
+document.
+</li>
+</ul>
+</section>
+<section id= "changes-in-wd-published-september-7-2022-from-the-fpwd-version">
+<div class="header-wrapper">
+<h3 id="changes-from-fpwd-1.1">
+<bdi class="secno">
+A.4
+</bdi>
+Changes
+in
+WD
+published
+September
+7,
+2022
+from
+the
+FPWD
+version
+</h3>
+<a class="self-link" href="#changes-from-fpwd-1.1" aria-label= "Permalink for Appendix A.4">
+</a>
+</div>
+<ul>
+<li>
+Move
+Toru
+Kawaguchi
+to
+former
+editors.
+</li>
+<li>
+Update
+abstract
+to
+reflect
+use
+of
+prescription
+(as
+opposed
+to
+pure
+description)
+where
+necessary.
+</li>
+<li>
+New
+section
+under
+Terminology:
+Device
+Categories.
+</li>
+<li>
+Section
+removed:
+System
+Integration.
+</li>
+<li>
+Lifecycle
+section
+reworked;
+removal
+of
+separate
+"Information
+Lifecycle"
+section.
+</li>
+<li>
+Reference
+and
+discuss
+new
+WoT
+building
+block
+and
+document:
+WoT
+Discovery
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-wot-discovery" title= "Web of Things (WoT) Discovery">
+WOT-DISCOVERY
+</a>
+</cite>
+]
+</li>
+<li>
+Update
+discussion
+of
+WoT
+Profiles
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href="#bib-wot-profile" title= "Web of Things (WoT) Profile">
+WOT-PROFILE
+</a>
+</cite>
+]
+</li>
+<li>
+Update
+discussion
+of
+WoT
+Binding
+Templates
+[
+<cite>
+<a class= "bibref" data-link-type="biblio" href="#bib-wot-binding-templates" title= "Web of Things (WoT) Binding Templates">
+WOT-BINDING-TEMPLATES
+</a>
+</cite>
+]
+</li>
+<li>
+Rename
+"System
+Topologies
+(Horizontals)"
+to
+"Common
+Deployment
+Patterns".
+</li>
+<li>
+Rename
+"Application
+Domains
+(Verticals)"
+to
+"Application
+Domains".
+</li>
+<li>
+New
+or
+revised
+deployment
+patterns:
+<ul>
+<li>
+Telemetry
+</li>
+<li>
+Orchestration
+</li>
+<li>
+Virtual
+Things
+</li>
+</ul>
+</li>
+<li>
+Revise
+Security
+Considerations
+and
+Privacy
+Considerations:
+<ul>
+<li>
+Reorganized
+to
+ensure
+that
+risks
+and
+mitigations
+are
+presented
+separately,
+and
+that
+normative
+content
+is
+only
+given
+under
+mitigations.
+</li>
+<li>
+Added
+new
+section
+for
+Access
+to
+PII
+covering
+actual
+data
+access,
+not
+just
+metadata.
+</li>
+<li>
+Added
+new
+section
+for
+Trusted
+Environments.
+</li>
+<li>
+Added
+new
+section
+for
+Secure
+Transport.
+This
+section
+defines
+under
+what
+conditions
+(D)TLS
+should
+or
+must
+be
+used.
+</li>
+</ul>
+</li>
+</ul>
+</section>
+<section id= "changes-in-the-fpwd-from-the-1-0-version-of-wot-architecture">
+<div class="header-wrapper">
+<h3 id="changes-in-fpwd-1.1-from-recommendation-1.0">
+<bdi class= "secno">
+A.5
+</bdi>
+Changes
+in
+the
+FPWD
+from
+the
+1.0
+version
+of
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-wot-architecture" title= "Web of Things (WoT) Architecture">
+wot-architecture
+</a>
+</cite>
+]
+</h3>
+<a class="self-link" href= "#changes-in-fpwd-1.1-from-recommendation-1.0" aria-label= "Permalink for Appendix A.5">
+</a>
+</div>
+<ul>
+<li>
+Make
+Security
+Considerations
+and
+Privacy
+Considerations
+normative.
+</li>
+<li>
+Add
+definitions
+for
+Connected
+Device
+(a.k.a.
+Device),
+Service,
+and
+Shadow.
+Update
+definitions
+for
+Virtual
+Thing
+and
+Digital
+Twin.
+Narrow
+definition
+of
+Virtual
+Thing
+to
+a
+Service
+that
+mediates
+with
+one
+of
+more
+other
+Things.
+</li>
+<li>
+Split
+Security
+and
+Privacy
+Considerations
+into
+separate
+chapters.
+</li>
+<li>
+New
+chapter:
+Lifecycle.
+</li>
+<li>
+New
+terminology:
+Thing
+Model.
+</li>
+<li>
+Chapter
+restructuring
+and
+renaming:
+<ul>
+<li>
+Application
+Domains
+(Verticals)
+</li>
+<li>
+System
+Topologies
+(Horizontals)
+</li>
+<li>
+System
+Integration
+</li>
+<li>
+Abstract
+WoT
+System
+Architecture
+</li>
+</ul>
+</li>
+<li>
+Various
+editors
+notes
+with
+placeholders
+for
+planned
+contributions.
+</li>
+<li>
+References
+to
+github
+repositories
+for
+use
+cases
+and
+requirements.
+</li>
+<li>
+Requirement
+chapter
+was
+moved
+to
+the
+<em>
+WoT
+Use
+Cases
+and
+Requirements
+</em>
+document
+[
+<cite>
+<a class="bibref" data-link-type= "biblio" href="#bib-wot-use-cases-requirements" title= "Web of Things (WoT) Use Cases and Requirements">
+WOT-USE-CASES-REQUIREMENTS
+</a>
+</cite>
+].
+</li>
+</ul>
+</section>
+</section>
+<section id="acknowledgements" class="appendix normative">
+<div class="header-wrapper">
+<h2 id="b-acknowledgments">
+<bdi class="secno">
+B.
+</bdi>
+Acknowledgments
+</h2>
+<a class="self-link" href="#acknowledgements" aria-label= "Permalink for Appendix B.">
+</a>
+</div>
+<p>
+Special
+thanks
+to
+Kazuo
+Kajimoto,
+Toru
+Kawaguchi,
+and
+Matthias
+Kovatsch
+for
+co-editing
+and
+many
+significant
+contributions
+to
+the
+initial
+version
+of
+the
+WoT
+architecture
+specification.
+Special
+thanks
+to
+Cristiano
+Aguzzi,
+Andrea
+Cimmino
+Arriaga,
+Kazuyuki
+Ashimura,
+Luca
+Barbato,
+Ben
+Francis,
+Christian
+Glomb,
+Klaus
+Hartke,
+Sebastian
+Käbisch,
+Takuki
+Kamiya,
+Ari
+Keränen,
+Zoltan
+Kis,
+Ege
+Korkan,
+Michael
+Koster,
+Philippe
+Le
+Hegaret,
+Kazuaki
+Nimura,
+Daniel
+Peintner,
+James
+Pullen,
+Elena
+Reshetova,
+and
+Farshid
+Tavakolizadeh
+for
+their
+contributions
+to
+this
+document.
+</p>
+<p>
+Special
+thanks
+to
+Dr.
+Kazuyuki
+Ashimura
+from
+the
+<abbr title= "World Wide Web Consortium">
+W3C
+</abbr>
+for
+the
+continuous
+help
+and
+support
+of
+the
+work
+of
+the
+WoT
+Architecture
+Task
+Force.
+</p>
+<p>
+Many
+thanks
+to
+the
+<abbr title= "World Wide Web Consortium">
+W3C
+</abbr>
+staff
+and
+all
+other
+active
+Participants
+of
+the
+<abbr title= "World Wide Web Consortium">
+W3C
+</abbr>
+Web
+of
+Things
+Interest
+Group
+(WoT
+IG)
+and
+Working
+Group
+(WoT
+WG)
+for
+their
+support,
+technical
+input
+and
+suggestions
+that
+led
+to
+improvements
+to
+this
+document.
+</p>
+<p>
+The
+WoT
+WG
+also
+would
+like
+to
+appreciate
+the
+pioneering
+efforts
+regarding
+the
+concept
+of
+"Web
+of
+Things"
+that
+started
+as
+an
+academic
+initiative
+in
+the
+form
+of
+publications
+such
+as
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-wot-pioneers-1" title= "Mobile Service Interaction with the Web of Things">
+WOT-PIONEERS-1
+</a>
+</cite>
+]
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-wot-pioneers-2" title= "Putting Things to REST">
+WOT-PIONEERS-2
+</a>
+</cite>
+]
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-wot-pioneers-3" title= "Poster Abstract: Dyser – Towards a Real-Time Search Engine for the Web of Things">
+WOT-PIONEERS-3
+</a>
+</cite>
+]
+[
+<cite>
+<a class="bibref" data-link-type="biblio" href= "#bib-wot-pioneers-4" title= "A Resource Oriented Architecture for the Web of Things">
+WOT-PIONEERS-4
+</a>
+</cite>
+]
+and,
+starting
+in
+2010,
+an
+<i>
+International
+Workshop
+on
+the
+Web
+of
+Things
+</i>.
+</p>
+<p>
+Finally,
+special
+thanks
+to
+Joerg
+Heuer
+for
+leading
+the
+WoT
+IG
+for
+2
+years
+from
+its
+inception
+and
+guiding
+the
+group
+to
+come
+up
+with
+the
+concept
+of
+WoT
+building
+blocks
+including
+the
+Thing
+Description.
+</p>
+</section>
+<section id="references" class="appendix">
+<div class="header-wrapper">
+<h2 id="c-references">
+<bdi class="secno">
+C.
+</bdi>
+References
+</h2>
+<a class="self-link" href="#references" aria-label= "Permalink for Appendix C.">
+</a>
+</div>
+<section id="normative-references">
+<div class="header-wrapper">
+<h3 id="c-1-normative-references">
+<bdi class="secno">
+C.1
+</bdi>
+Normative
+references
+</h3>
+<a class="self-link" href="#normative-references" aria-label= "Permalink for Appendix C.1">
+</a>
+</div>
+<dl class="bibliography">
+<dt id="bib-bcp47">
+[BCP47]
+</dt>
+<dd>
+<a href="https://www.rfc-editor.org/rfc/rfc5646">
+<cite>
+Tags
+for
+Identifying
+Languages
+</cite>
+</a>.
+A.
+Phillips,
+Ed.;
+M.
+Davis,
+Ed..
+IETF.
+September
+2009.
+Best
+Current
+Practice.
+URL:
+<a href= "https://www.rfc-editor.org/rfc/rfc5646">
+https://www.rfc-editor.org/rfc/rfc5646
+</a>
+</dd>
+<dt id="bib-json-ld">
+[JSON-LD]
+</dt>
+<dd>
+<a href="https://www.w3.org/TR/json-ld/">
+<cite>
+JSON-LD
+1.0
+</cite>
+</a>.
+Manu
+Sporny;
+Gregg
+Kellogg;
+Markus
+Lanthaler.
+W3C.
+3
+November
+2020.
+W3C
+Recommendation.
+URL:
+<a href= "https://www.w3.org/TR/json-ld/">
+https://www.w3.org/TR/json-ld/
+</a>
+</dd>
+<dt id="bib-rfc2046">
+[RFC2046]
+</dt>
+<dd>
+<a href= "https://www.rfc-editor.org/rfc/rfc2046">
+<cite>
+Multipurpose
+Internet
+Mail
+Extensions
+(MIME)
+Part
+Two:
+Media
+Types
+</cite>
+</a>.
+N.
+Freed;
+N.
+Borenstein.
+IETF.
+November
+1996.
+Draft
+Standard.
+URL:
+<a href= "https://www.rfc-editor.org/rfc/rfc2046">
+https://www.rfc-editor.org/rfc/rfc2046
+</a>
+</dd>
+<dt id="bib-rfc2119">
+[RFC2119]
+</dt>
+<dd>
+<a href="https://www.rfc-editor.org/rfc/rfc2119">
+<cite>
+Key
+words
+for
+use
+in
+RFCs
+to
+Indicate
+Requirement
+Levels
+</cite>
+</a>.
+S.
+Bradner.
+IETF.
+March
+1997.
+Best
+Current
+Practice.
+URL:
+<a href= "https://www.rfc-editor.org/rfc/rfc2119">
+https://www.rfc-editor.org/rfc/rfc2119
+</a>
+</dd>
+<dt id="bib-rfc3986">
+[RFC3986]
+</dt>
+<dd>
+<a href="https://www.rfc-editor.org/rfc/rfc3986">
+<cite>
+Uniform
+Resource
+Identifier
+(URI):
+Generic
+Syntax
+</cite>
+</a>.
+T.
+Berners-Lee;
+R.
+Fielding;
+L.
+Masinter.
+IETF.
+January
+2005.
+Internet
+Standard.
+URL:
+<a href= "https://www.rfc-editor.org/rfc/rfc3986">
+https://www.rfc-editor.org/rfc/rfc3986
+</a>
+</dd>
+<dt id="bib-rfc3987">
+[RFC3987]
+</dt>
+<dd>
+<a href= "https://www.rfc-editor.org/rfc/rfc3987">
+<cite>
+Internationalized
+Resource
+Identifiers
+(IRIs)
+</cite>
+</a>.
+M.
+Duerst;
+M.
+Suignard.
+IETF.
+January
+2005.
+Proposed
+Standard.
+URL:
+<a href= "https://www.rfc-editor.org/rfc/rfc3987">
+https://www.rfc-editor.org/rfc/rfc3987
+</a>
+</dd>
+<dt id="bib-rfc5246">
+[RFC5246]
+</dt>
+<dd>
+<a href="https://www.rfc-editor.org/rfc/rfc5246">
+<cite>
+The
+Transport
+Layer
+Security
+(TLS)
+Protocol
+Version
+1.2
+</cite>
+</a>.
+T.
+Dierks;
+E.
+Rescorla.
+IETF.
+August
+2008.
+Proposed
+Standard.
+URL:
+<a href= "https://www.rfc-editor.org/rfc/rfc5246">
+https://www.rfc-editor.org/rfc/rfc5246
+</a>
+</dd>
+<dt id="bib-rfc6347">
+[RFC6347]
+</dt>
+<dd>
+<a href="https://www.rfc-editor.org/rfc/rfc6347">
+<cite>
+Datagram
+Transport
+Layer
+Security
+Version
+1.2
+</cite>
+</a>.
+E.
+Rescorla;
+N.
+Modadugu.
+IETF.
+January
+2012.
+Proposed
+Standard.
+URL:
+<a href= "https://www.rfc-editor.org/rfc/rfc6347">
+https://www.rfc-editor.org/rfc/rfc6347
+</a>
+</dd>
+<dt id="bib-rfc8174">
+[RFC8174]
+</dt>
+<dd>
+<a href= "https://www.rfc-editor.org/rfc/rfc8174">
+<cite>
+Ambiguity
+of
+Uppercase
+vs
+Lowercase
+in
+RFC
+2119
+Key
+Words
+</cite>
+</a>.
+B.
+Leiba.
+IETF.
+May
+2017.
+Best
+Current
+Practice.
+URL:
+<a href= "https://www.rfc-editor.org/rfc/rfc8174">
+https://www.rfc-editor.org/rfc/rfc8174
+</a>
+</dd>
+<dt id="bib-rfc8259">
+[RFC8259]
+</dt>
+<dd>
+<a href="https://www.rfc-editor.org/rfc/rfc8259">
+<cite>
+The
+JavaScript
+Object
+Notation
+(JSON)
+Data
+Interchange
+Format
+</cite>
+</a>.
+T.
+Bray,
+Ed..
+IETF.
+December
+2017.
+Internet
+Standard.
+URL:
+<a href= "https://www.rfc-editor.org/rfc/rfc8259">
+https://www.rfc-editor.org/rfc/rfc8259
+</a>
+</dd>
+<dt id="bib-rfc8288">
+[RFC8288]
+</dt>
+<dd>
+<a href="https://httpwg.org/specs/rfc8288.html">
+<cite>
+Web
+Linking
+</cite>
+</a>.
+M.
+Nottingham.
+IETF.
+October
+2017.
+Proposed
+Standard.
+URL:
+<a href= "https://httpwg.org/specs/rfc8288.html">
+https://httpwg.org/specs/rfc8288.html
+</a>
+</dd>
+<dt id="bib-rfc8446">
+[RFC8446]
+</dt>
+<dd>
+<a href="https://www.rfc-editor.org/rfc/rfc8446">
+<cite>
+The
+Transport
+Layer
+Security
+(TLS)
+Protocol
+Version
+1.3
+</cite>
+</a>.
+E.
+Rescorla.
+IETF.
+August
+2018.
+Proposed
+Standard.
+URL:
+<a href= "https://www.rfc-editor.org/rfc/rfc8446">
+https://www.rfc-editor.org/rfc/rfc8446
+</a>
+</dd>
+<dt id="bib-rfc9147">
+[RFC9147]
+</dt>
+<dd>
+<a href="https://www.rfc-editor.org/rfc/rfc9147">
+<cite>
+The
+Datagram
+Transport
+Layer
+Security
+(DTLS)
+Protocol
+Version
+1.3
+</cite>
+</a>.
+E.
+Rescorla;
+H.
+Tschofenig;
+N.
+Modadugu.
+IETF.
+April
+2022.
+Proposed
+Standard.
+URL:
+<a href= "https://www.rfc-editor.org/rfc/rfc9147">
+https://www.rfc-editor.org/rfc/rfc9147
+</a>
+</dd>
+<dt id="bib-wot-architecture">
+[wot-architecture]
+</dt>
+<dd>
+<a href="https://www.w3.org/TR/wot-architecture/">
+<cite>
+Web
+of
+Things
+(WoT)
+Architecture
+</cite>
+</a>.
+Matthias
+Kovatsch;
+Ryuichi
+Matsukura;
+Michael
+Lagally;
+Toru
+Kawaguchi;
+Kunihiko
+Toumura;
+Kazuo
+Kajimoto.
+W3C.
+9
+April
+2020.
+W3C
+Recommendation.
+URL:
+<a href= "https://www.w3.org/TR/wot-architecture/">
+https://www.w3.org/TR/wot-architecture/
+</a>
+</dd>
+<dt id="bib-wot-discovery">
+[WOT-DISCOVERY]
+</dt>
+<dd>
+<a href="https://www.w3.org/TR/wot-discovery/">
+<cite>
+Web
+of
+Things
+(WoT)
+Discovery
+</cite>
+</a>.
+Andrea
+Cimmino;
+Michael
+McCool;
+Farshid
+Tavakolizadeh;
+Kunihiko
+Toumura.
+W3C.
+<del class="diff-old">30
+November
+</del>
+<ins class="diff-chg">5
+December
+</ins>
+2023.
+<ins class="diff-new">W3C
+Recommendation.
+</ins>
+URL:
+<a href= "https://www.w3.org/TR/wot-discovery/">
+https://www.w3.org/TR/wot-discovery/
+</a>
+</dd>
+<dt id="bib-wot-profile">
+[WOT-PROFILE]
+</dt>
+<dd>
+<a href="https://www.w3.org/TR/wot-profile/">
+<cite>
+Web
+of
+Things
+(WoT)
+Profile
+</cite>
+</a>.
+Michael
+Lagally;
+Ben
+Francis;
+Michael
+McCool;
+Ryuichi
+Matsukura;
+Sebastian
+Käbisch;
+Tomoaki
+Mizushima.
+W3C.
+18
+January
+2023.
+W3C
+Working
+Draft.
+URL:
+<a href= "https://www.w3.org/TR/wot-profile/">
+https://www.w3.org/TR/wot-profile/
+</a>
+</dd>
+<dt id="bib-wot-thing-description">
+[WOT-THING-DESCRIPTION]
+</dt>
+<dd>
+<a href= "https://www.w3.org/TR/wot-thing-description11/">
+<cite>
+Web
+of
+Things
+(WoT)
+Thing
+Description
+1.1
+</cite>
+</a>.
+Sebastian
+Kaebisch;
+<ins class="diff-new">Takuki
+Kamiya;
+</ins>
+Michael
+McCool;
+<del class="diff-old">Ege
+Korkan.
+</del>
+<ins class="diff-chg">Victor
+Charpenay.
+</ins>
+W3C.
+<del class="diff-old">30
+November
+</del>
+<ins class="diff-chg">5
+December
+</ins>
+2023.
+<ins class="diff-new">W3C
+Recommendation.
+</ins>
+URL:
+<a href= "https://www.w3.org/TR/wot-thing-description11/">
+https://www.w3.org/TR/wot-thing-description11/
+</a>
+</dd>
+<dt id="bib-wot-use-cases-requirements">
+[WOT-USE-CASES-REQUIREMENTS]
+</dt>
+<dd>
+<a href="https://www.w3.org/TR/wot-usecases/">
+<cite>
+Web
+of
+Things
+(WoT)
+Use
+Cases
+and
+Requirements
+</cite>
+</a>.
+Michael
+Lagally;
+Michael
+McCool;
+Ryuichi
+Matsukura;
+Tomoaki
+Mizushima.
+W3C.
+Oct
+2020.
+Editor's
+Draft.
+URL:
+<a href= "https://www.w3.org/TR/wot-usecases/">
+https://www.w3.org/TR/wot-usecases/
+</a>
+</dd>
+</dl>
+</section>
+<section id="informative-references">
+<div class="header-wrapper">
+<h3 id="c-2-informative-references">
+<bdi class="secno">
+C.2
+</bdi>
+Informative
+references
+</h3>
+<a class="self-link" href="#informative-references" aria-label= "Permalink for Appendix C.2">
+</a>
+</div>
+<dl class="bibliography">
+<dt id="bib-coral">
+[CoRAL]
+</dt>
+<dd>
+<a href= "https://datatracker.ietf.org/doc/html/draft-ietf-core-coral/">
+<cite>
+The
+Constrained
+RESTful
+Application
+Language
+(CoRAL)
+</cite>
+</a>.
+Christian
+Amsüss;
+Thomas
+Fossati.
+IETF.
+March
+2022.
+Internet-Draft.
+URL:
+<a href= "https://datatracker.ietf.org/doc/html/draft-ietf-core-coral/">
+https://datatracker.ietf.org/doc/html/draft-ietf-core-coral/
+</a>
+</dd>
+<dt id="bib-ecmascript">
+[ECMAScript]
+</dt>
+<dd>
+<a href="https://tc39.es/ecma262/multipage/">
+<cite>
+ECMAScript
+Language
+Specification
+</cite>
+</a>.
+Ecma
+International.
+URL:
+<a href="https://tc39.es/ecma262/multipage/">
+https://tc39.es/ecma262/multipage/
+</a>
+</dd>
+<dt id="bib-etsi-en-301-549">
+[etsi-en-301-549]
+</dt>
+<dd>
+<a href= "http://www.etsi.org/deliver/etsi_en/301500_301599/301549/02.01.02_60/en_301549v020102p.pdf">
+<cite>
+ETSI
+EN
+301
+549
+V2.1.2
+(2018-08):
+Accessibility
+requirements
+for
+ICT
+products
+and
+services
+</cite>
+</a>.
+ETSI.
+August
+2018.
+Published.
+URL:
+<a href= "http://www.etsi.org/deliver/etsi_en/301500_301599/301549/02.01.02_60/en_301549v020102p.pdf">
+http://www.etsi.org/deliver/etsi_en/301500_301599/301549/02.01.02_60/en_301549v020102p.pdf
+</a>
+</dd>
+<dt id="bib-hci">
+[HCI]
+</dt>
+<dd>
+<a href= "https://www.interaction-design.org/literature/book/the-encyclopedia-of-human-computer-interaction-2nd-ed">
+<cite>
+The
+Encyclopedia
+of
+Human-Computer
+Interaction,
+2nd
+Ed
+</cite>
+</a>.
+Interaction
+Design
+Foundation.
+2013.
+URL:
+<a href= "https://www.interaction-design.org/literature/book/the-encyclopedia-of-human-computer-interaction-2nd-ed">
+https://www.interaction-design.org/literature/book/the-encyclopedia-of-human-computer-interaction-2nd-ed
+</a>
+</dd>
+<dt id="bib-html">
+[HTML]
+</dt>
+<dd>
+<a href="https://html.spec.whatwg.org/multipage/">
+<cite>
+HTML
+Standard
+</cite>
+</a>.
+Anne
+van
+Kesteren;
+Domenic
+Denicola;
+Ian
+Hickson;
+Philip
+Jägenstedt;
+Simon
+Pieters.
+WHATWG.
+Living
+Standard.
+URL:
+<a href= "https://html.spec.whatwg.org/multipage/">
+https://html.spec.whatwg.org/multipage/
+</a>
+</dd>
+<dt id="bib-iana-relations">
+[IANA-RELATIONS]
+</dt>
+<dd>
+<a href= "https://www.iana.org/assignments/link-relations/">
+<cite>
+Link
+Relations
+</cite>
+</a>.
+IANA.
+URL:
+<a href= "https://www.iana.org/assignments/link-relations/">
+https://www.iana.org/assignments/link-relations/
+</a>
+</dd>
+<dt id="bib-iec-fotf">
+[IEC-FOTF]
+</dt>
+<dd>
+<a href= "https://www.iec.ch/basecamp/factory-future">
+<cite>
+Factory
+of
+the
+future
+</cite>
+</a>.
+IEC.
+October
+2015.
+URL:
+<a href= "https://www.iec.ch/basecamp/factory-future">
+https://www.iec.ch/basecamp/factory-future
+</a>
+</dd>
+<dt id="bib-iot-schema-org">
+[IOT-SCHEMA-ORG]
+</dt>
+<dd>
+<a href="https://www.w3.org/community/iotschema/">
+<cite>
+Schema
+Extensions
+for
+IoT
+Community
+Group
+</cite>
+</a>.
+URL:
+<a href= "https://www.w3.org/community/iotschema/">
+https://www.w3.org/community/iotschema/
+</a>
+</dd>
+<dt id="bib-iso-iec-2382">
+[ISO-IEC-2382]
+</dt>
+<dd>
+<a href= "https://www.iso.org/obp/ui/#iso:std:iso-iec:2382:ed-1:v2:en">
+<cite>
+Information
+technology
+—
+Vocabulary
+</cite>
+</a>.
+ISO.
+2015.
+URL:
+<a href= "https://www.iso.org/obp/ui/#iso:std:iso-iec:2382:ed-1:v2:en">
+https://www.iso.org/obp/ui/#iso:std:iso-iec:2382:ed-1:v2:en
+</a>
+</dd>
+<dt id="bib-iso-iec-27000">
+[ISO-IEC-27000]
+</dt>
+<dd>
+<a href= "https://www.iso.org/obp/ui/#iso:std:iso-iec:27000:ed-5:v1:en">
+<cite>
+Information
+technology
+—
+Security
+techniques
+—
+Information
+security
+management
+systems
+—
+Overview
+and
+vocabulary
+</cite>
+</a>.
+ISO.
+2018.
+URL:
+<a href= "https://www.iso.org/obp/ui/#iso:std:iso-iec:27000:ed-5:v1:en">
+https://www.iso.org/obp/ui/#iso:std:iso-iec:27000:ed-5:v1:en
+</a>
+</dd>
+<dt id="bib-iso-iec-29100">
+[ISO-IEC-29100]
+</dt>
+<dd>
+<a href= "https://www.iso.org/obp/ui/#iso:std:iso-iec:29100:ed-1:v1:en">
+<cite>
+Information
+technology
+—
+Security
+techniques
+—
+Privacy
+framework
+</cite>
+</a>.
+ISO.
+2011.
+URL:
+<a href= "https://www.iso.org/obp/ui/#iso:std:iso-iec:29100:ed-1:v1:en">
+https://www.iso.org/obp/ui/#iso:std:iso-iec:29100:ed-1:v1:en
+</a>
+</dd>
+<dt id="bib-json-ld11">
+[JSON-LD11]
+</dt>
+<dd>
+<a href="https://www.w3.org/TR/json-ld11/">
+<cite>
+JSON-LD
+1.1
+</cite>
+</a>.
+Gregg
+Kellogg;
+Pierre-Antoine
+Champin;
+Dave
+Longley.
+W3C.
+16
+July
+2020.
+W3C
+Recommendation.
+URL:
+<a href= "https://www.w3.org/TR/json-ld11/">
+https://www.w3.org/TR/json-ld11/
+</a>
+</dd>
+<dt id="bib-linked-data">
+[LINKED-DATA]
+</dt>
+<dd>
+<a href= "https://www.w3.org/DesignIssues/LinkedData.html">
+<cite>
+Linked
+Data
+Design
+Issues
+</cite>
+</a>.
+Tim
+Berners-Lee.
+W3C.
+27
+July
+2006.
+W3C-Internal
+Document.
+URL:
+<a href= "https://www.w3.org/DesignIssues/LinkedData.html">
+https://www.w3.org/DesignIssues/LinkedData.html
+</a>
+</dd>
+<dt id="bib-lwm2m">
+[LWM2M]
+</dt>
+<dd>
+<a href= "https://openmobilealliance.org/release/LightweightM2M/V1_1-20180710-A/OMA-TS-LightweightM2M_Core-V1_1-20180710-A.pdf">
+<cite>
+Lightweight
+Machine
+to
+Machine
+Technical
+Specification:
+Core
+</cite>
+</a>.
+OMA
+SpecWorks.
+August
+2018.
+Approved
+Version:
+1.1.
+URL:
+<a href= "https://openmobilealliance.org/release/LightweightM2M/V1_1-20180710-A/OMA-TS-LightweightM2M_Core-V1_1-20180710-A.pdf">
+https://openmobilealliance.org/release/LightweightM2M/V1_1-20180710-A/OMA-TS-LightweightM2M_Core-V1_1-20180710-A.pdf
+</a>
+</dd>
+<dt id="bib-mqtt">
+[MQTT]
+</dt>
+<dd>
+<a href= "https://docs.oasis-open.org/mqtt/mqtt/v3.1.1/mqtt-v3.1.1.html">
+<cite>
+MQTT
+Version
+3.1.1
+Plus
+Errata
+01
+</cite>
+</a>.
+Andrew
+Banks;
+Rahul
+Gupta.
+OASIS
+Standard.
+December
+2015.
+URL:
+<a href= "https://docs.oasis-open.org/mqtt/mqtt/v3.1.1/mqtt-v3.1.1.html">
+https://docs.oasis-open.org/mqtt/mqtt/v3.1.1/mqtt-v3.1.1.html
+</a>
+</dd>
+<dt id="bib-norman">
+[NORMAN]
+</dt>
+<dd>
+<cite>
+The
+Psychology
+of
+Everyday
+Things
+</cite>.
+Donald
+A.
+Norman.
+Basic
+Books.
+1988.
+</dd>
+<dt id="bib-ocf">
+[OCF]
+</dt>
+<dd>
+<a href= "https://openconnectivity.org/developer/specifications/">
+<cite>
+OCF
+Core
+Specification
+</cite>
+</a>.
+Open
+Connectivity
+Foundation.
+April
+2019.
+Version
+2.0.2.
+URL:
+<a href= "https://openconnectivity.org/developer/specifications/">
+https://openconnectivity.org/developer/specifications/
+</a>
+</dd>
+<dt id="bib-rest">
+[REST]
+</dt>
+<dd>
+<a href= "https://www.ics.uci.edu/~fielding/pubs/dissertation/fielding_dissertation.pdf">
+<cite>
+REST:
+Architectural
+Styles
+and
+the
+Design
+of
+Network-based
+Software
+Architectures
+</cite>
+</a>.
+Roy
+Thomas
+Fielding.
+University
+of
+California,
+Irvine.
+2000.
+PhD
+thesis.
+URL:
+<a href= "https://www.ics.uci.edu/~fielding/pubs/dissertation/fielding_dissertation.pdf">
+https://www.ics.uci.edu/~fielding/pubs/dissertation/fielding_dissertation.pdf
+</a>
+</dd>
+<dt id="bib-rfc6202">
+[RFC6202]
+</dt>
+<dd>
+<a href="https://www.rfc-editor.org/rfc/rfc6202">
+<cite>
+Known
+Issues
+and
+Best
+Practices
+for
+the
+Use
+of
+Long
+Polling
+and
+Streaming
+in
+Bidirectional
+HTTP
+</cite>
+</a>.
+S.
+Loreto;
+P.
+Saint-Andre;
+S.
+Salsano;
+G.
+Wilkins.
+IETF.
+April
+2011.
+Informational.
+URL:
+<a href= "https://www.rfc-editor.org/rfc/rfc6202">
+https://www.rfc-editor.org/rfc/rfc6202
+</a>
+</dd>
+<dt id="bib-rfc6690">
+[RFC6690]
+</dt>
+<dd>
+<a href= "https://www.rfc-editor.org/rfc/rfc6690">
+<cite>
+Constrained
+RESTful
+Environments
+(CoRE)
+Link
+Format
+</cite>
+</a>.
+Z.
+Shelby.
+IETF.
+August
+2012.
+Proposed
+Standard.
+URL:
+<a href= "https://www.rfc-editor.org/rfc/rfc6690">
+https://www.rfc-editor.org/rfc/rfc6690
+</a>
+</dd>
+<dt id="bib-rfc7049">
+[RFC7049]
+</dt>
+<dd>
+<a href="https://www.rfc-editor.org/rfc/rfc7049">
+<cite>
+Concise
+Binary
+Object
+Representation
+(CBOR)
+</cite>
+</a>.
+C.
+Bormann;
+P.
+Hoffman.
+IETF.
+October
+2013.
+Proposed
+Standard.
+URL:
+<a href= "https://www.rfc-editor.org/rfc/rfc7049">
+https://www.rfc-editor.org/rfc/rfc7049
+</a>
+</dd>
+<dt id="bib-rfc7228">
+[RFC7228]
+</dt>
+<dd>
+<a href= "https://www.rfc-editor.org/rfc/rfc7228">
+<cite>
+Terminology
+for
+Constrained-Node
+Networks
+</cite>
+</a>.
+C.
+Bormann;
+M.
+Ersue;
+A.
+Keranen.
+IETF.
+May
+2014.
+Informational.
+URL:
+<a href= "https://www.rfc-editor.org/rfc/rfc7228">
+https://www.rfc-editor.org/rfc/rfc7228
+</a>
+</dd>
+<dt id="bib-rfc7231">
+[RFC7231]
+</dt>
+<dd>
+<a href="https://httpwg.org/specs/rfc7231.html">
+<cite>
+Hypertext
+Transfer
+Protocol
+(HTTP/1.1):
+Semantics
+and
+Content
+</cite>
+</a>.
+R.
+Fielding,
+Ed.;
+J.
+Reschke,
+Ed..
+IETF.
+June
+2014.
+Proposed
+Standard.
+URL:
+<a href= "https://httpwg.org/specs/rfc7231.html">
+https://httpwg.org/specs/rfc7231.html
+</a>
+</dd>
+<dt id="bib-rfc7252">
+[RFC7252]
+</dt>
+<dd>
+<a href="https://www.rfc-editor.org/rfc/rfc7252">
+<cite>
+The
+Constrained
+Application
+Protocol
+(CoAP)
+</cite>
+</a>.
+Z.
+Shelby;
+K.
+Hartke;
+C.
+Bormann.
+IETF.
+June
+2014.
+Proposed
+Standard.
+URL:
+<a href= "https://www.rfc-editor.org/rfc/rfc7252">
+https://www.rfc-editor.org/rfc/rfc7252
+</a>
+</dd>
+<dt id="bib-rfc7641">
+[RFC7641]
+</dt>
+<dd>
+<a href= "https://www.rfc-editor.org/rfc/rfc7641">
+<cite>
+Observing
+Resources
+in
+the
+Constrained
+Application
+Protocol
+(CoAP)
+</cite>
+</a>.
+K.
+Hartke.
+IETF.
+September
+2015.
+Proposed
+Standard.
+URL:
+<a href= "https://www.rfc-editor.org/rfc/rfc7641">
+https://www.rfc-editor.org/rfc/rfc7641
+</a>
+</dd>
+<dt id="bib-saref">
+[SAREF]
+</dt>
+<dd>
+<a href= "https://sites.google.com/site/smartappliancesproject/ontologies/reference-ontology">
+<cite>
+Smart
+Appliances
+REFerence
+(SAREF)
+ontology
+</cite>
+</a>.
+ETSI.
+November
+2015.
+URL:
+<a href= "https://sites.google.com/site/smartappliancesproject/ontologies/reference-ontology">
+https://sites.google.com/site/smartappliancesproject/ontologies/reference-ontology
+</a>
+</dd>
+<dt id="bib-solid">
+[SOLID]
+</dt>
+<dd>
+<a href="https://solidproject.org/TR/">
+<cite>
+Solid
+Technical
+Reports
+</cite>
+</a>.
+W3C
+Solid
+CG.
+April
+2021.
+URL:
+<a href= "https://solidproject.org/TR/">
+https://solidproject.org/TR/
+</a>
+</dd>
+<dt id="bib-vocab-ssn">
+[VOCAB-SSN]
+</dt>
+<dd>
+<a href="https://www.w3.org/TR/vocab-ssn/">
+<cite>
+Semantic
+Sensor
+Network
+Ontology
+</cite>
+</a>.
+Armin
+Haller;
+Krzysztof
+Janowicz;
+Simon
+Cox;
+Danh
+Le
+Phuoc;
+Kerry
+Taylor;
+Maxime
+Lefrançois.
+W3C.
+19
+October
+2017.
+W3C
+Recommendation.
+URL:
+<a href= "https://www.w3.org/TR/vocab-ssn/">
+https://www.w3.org/TR/vocab-ssn/
+</a>
+</dd>
+<dt id="bib-wcag22">
+[WCAG22]
+</dt>
+<dd>
+<a href="https://www.w3.org/TR/WCAG22/">
+<cite>
+Web
+Content
+Accessibility
+Guidelines
+(WCAG)
+2.2
+</cite>
+</a>.
+Michael
+Cooper;
+Andrew
+Kirkpatrick;
+Alastair
+Campbell;
+Rachael
+Bradley
+Montgomery;
+Charles
+Adams.
+W3C.
+5
+October
+2023.
+W3C
+Recommendation.
+URL:
+<a href= "https://www.w3.org/TR/WCAG22/">
+https://www.w3.org/TR/WCAG22/
+</a>
+</dd>
+<dt id="bib-wot-binding-templates">
+[WOT-BINDING-TEMPLATES]
+</dt>
+<dd>
+<a href= "https://www.w3.org/TR/wot-binding-templates/">
+<cite>
+Web
+of
+Things
+(WoT)
+Binding
+Templates
+</cite>
+</a>.
+Michael
+Koster;
+Ege
+Korkan.
+W3C.
+28
+September
+2023.
+W3C
+Working
+Group
+Note.
+URL:
+<a href= "https://www.w3.org/TR/wot-binding-templates/">
+https://www.w3.org/TR/wot-binding-templates/
+</a>
+</dd>
+<dt id="bib-wot-pioneers-1">
+[WOT-PIONEERS-1]
+</dt>
+<dd>
+<a href= "https://pdfs.semanticscholar.org/3ee3/a2e8ce93fbf9ba14ad54e12adaeb1f3ca392.pdf">
+<cite>
+Mobile
+Service
+Interaction
+with
+the
+Web
+of
+Things
+</cite>
+</a>.
+E.
+Rukzio,
+M.
+Paolucci;
+M.
+Wagner,
+H.
+Berndt;
+J.
+Hamard;
+A.
+Schmidt.
+Proceedings
+of
+13th
+International
+Conference
+on
+Telecommunications
+(ICT
+2006),
+Funchal,
+Madeira
+island,
+Portugal.
+May
+2006.
+URL:
+<a href= "https://pdfs.semanticscholar.org/3ee3/a2e8ce93fbf9ba14ad54e12adaeb1f3ca392.pdf">
+https://pdfs.semanticscholar.org/3ee3/a2e8ce93fbf9ba14ad54e12adaeb1f3ca392.pdf
+</a>
+</dd>
+<dt id="bib-wot-pioneers-2">
+[WOT-PIONEERS-2]
+</dt>
+<dd>
+<a href= "https://escholarship.org/uc/item/1786t1dm">
+<cite>
+Putting
+Things
+to
+REST
+</cite>
+</a>.
+Erik
+Wilde.
+UCB
+iSchool
+Report
+2007-015,
+UC
+Berkeley,
+Berkeley,
+CA,
+USA.
+November
+2007.
+URL:
+<a href= "https://escholarship.org/uc/item/1786t1dm">
+https://escholarship.org/uc/item/1786t1dm
+</a>
+</dd>
+<dt id="bib-wot-pioneers-3">
+[WOT-PIONEERS-3]
+</dt>
+<dd>
+<a href= "https://www.vs.inf.ethz.ch/publ/papers/ostermai-poster-2008.pdf">
+<cite>
+Poster
+Abstract:
+Dyser
+–
+Towards
+a
+Real-Time
+Search
+Engine
+for
+the
+Web
+of
+Things
+</cite>
+</a>.
+Benedikt
+Ostermaier;
+B.
+Maryam
+Elahi;
+Kay
+Römer;
+Michael
+Fahrmair;
+Wolfgang
+Kellerer.
+Proceedings
+of
+ACM
+SenSys
+2008,
+Raleigh,
+NC,
+USA.
+November
+2008.
+URL:
+<a href= "https://www.vs.inf.ethz.ch/publ/papers/ostermai-poster-2008.pdf">
+https://www.vs.inf.ethz.ch/publ/papers/ostermai-poster-2008.pdf
+</a>
+</dd>
+<dt id="bib-wot-pioneers-4">
+[WOT-PIONEERS-4]
+</dt>
+<dd>
+<a href= "https://ieeexplore.ieee.org/abstract/document/5678452">
+<cite>
+A
+Resource
+Oriented
+Architecture
+for
+the
+Web
+of
+Things
+</cite>
+</a>.
+Dominique
+Guinard;
+Vlad
+Trifa;
+Erik
+Wilde.
+Proceedings
+of
+Internet
+of
+Things
+2010
+International
+Conference
+(IoT
+2010).
+Tokyo,
+Japan.
+November
+2010.
+URL:
+<a href= "https://ieeexplore.ieee.org/abstract/document/5678452">
+https://ieeexplore.ieee.org/abstract/document/5678452
+</a>
+</dd>
+<dt id="bib-wot-scripting-api">
+[WOT-SCRIPTING-API]
+</dt>
+<dd>
+<a href="https://www.w3.org/TR/wot-scripting-api/">
+<cite>
+Web
+of
+Things
+(WoT)
+Scripting
+API
+</cite>
+</a>.
+Zoltan
+Kis;
+Daniel
+Peintner;
+Cristiano
+Aguzzi;
+Johannes
+Hund;
+Kazuaki
+Nimura.
+W3C.
+3
+October
+2023.
+W3C
+Working
+Group
+Note.
+URL:
+<a href= "https://www.w3.org/TR/wot-scripting-api/">
+https://www.w3.org/TR/wot-scripting-api/
+</a>
+</dd>
+<dt id="bib-wot-security">
+[WOT-SECURITY]
+</dt>
+<dd>
+<a href="https://www.w3.org/TR/wot-security/">
+<cite>
+Web
+of
+Things
+(WoT)
+Security
+and
+Privacy
+Guidelines
+</cite>
+</a>.
+;
+Michael
+McCool;
+Elena
+Reshetova.
+W3C.
+March
+2019.
+URL:
+<a href= "https://www.w3.org/TR/wot-security/">
+https://www.w3.org/TR/wot-security/
+</a>
+</dd>
+<dt id="bib-y.4409-y.2070">
+[Y.4409-Y.2070]
+</dt>
+<dd>
+<a href= "https://www.itu.int/rec/T-REC-Y.2070-201501-I">
+<cite>
+ITU-T
+Rec.
+Y.4409/Y.2070
+(01/2015)
+Requirements
+and
+architecture
+of
+the
+home
+energy
+management
+system
+and
+home
+network
+services
+</cite>
+</a>
+.
+ITU-T.
+January
+2015.
+Recommendation.
+URL:
+<a href= "https://www.itu.int/rec/T-REC-Y.2070-201501-I">
+https://www.itu.int/rec/T-REC-Y.2070-201501-I
+</a>
+</dd>
+</dl>
+</section>
+</section>
+<p role="navigation" id="back-to-top">
+<a href="#title">
+<abbr title= "Back to Top">
+↑
+</abbr>
+</a>
+</p>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-action" aria-label= "Links in this document to definition: Action">
+<div>
+<a class="self-link" href="#dfn-action" aria-label= "Permalink for definition: Action. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-action-1" title="§ 3. Terminology">
+§
+3.
+Terminology
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-action-2" title= "§ 6.1.1.2 Thing Models">
+§
+6.1.1.2
+Thing
+Models
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-action-3" title="§ 6.2 Affordances">
+§
+6.2
+Affordances
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-action-4" title= "§ 6.5 Interaction Model">
+§
+6.5
+Interaction
+Model
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-action-5" title="§ 6.5.2 Actions">
+§
+6.5.2
+Actions
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-action-6" title="§ 7.2 Thing Model">
+§
+7.2
+Thing
+Model
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-action-7" title= "§ 7.6 WoT Scripting API">
+§
+7.6
+WoT
+Scripting
+API
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-wot-anonymous-thing-description" aria-label= "Links in this document to definition: Anonymous TD">
+<div>
+<a class="self-link" href= "#dfn-wot-anonymous-thing-description" aria-label= "Permalink for definition: Anonymous TD. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+Not
+referenced
+in
+this
+document.
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-connected-device" aria-label= "Links in this document to definition: Connected Device">
+<div>
+<a class="self-link" href="#dfn-connected-device" aria-label= "Permalink for definition: Connected Device. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-connected-device-1" title= "§ 3. Terminology">
+§
+3.
+Terminology
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-wot-binding-templates" aria-label= "Links in this document to definition: Binding Templates">
+<div>
+<a class="self-link" href="#dfn-wot-binding-templates" aria-label= "Permalink for definition: Binding Templates. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-wot-binding-templates-1" title= "§ 7. WoT Building Blocks">
+§
+7.
+WoT
+Building
+Blocks
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-binding-templates-2" title= "§ 7.5 WoT Binding Templates">
+§
+7.5
+WoT
+Binding
+Templates
+</a>
+<a href="#ref-for-dfn-wot-binding-templates-3" title= "Reference 2">
+(2)
+</a>
+<a href= "#ref-for-dfn-wot-binding-templates-4" title="Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-wot-binding-templates-5" title= "Reference 4">
+(4)
+</a>
+<a href= "#ref-for-dfn-wot-binding-templates-6" title="Reference 5">
+(5)
+</a>
+<a href="#ref-for-dfn-wot-binding-templates-7" title= "Reference 6">
+(6)
+</a>
+<a href= "#ref-for-dfn-wot-binding-templates-8" title= "Reference 7">
+(7)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-binding-templates-9" title= "§ 10.1.2 Thing Description Communication Metadata Risk">
+§
+10.1.2
+Thing
+Description
+Communication
+Metadata
+Risk
+</a>
+<a href= "#ref-for-dfn-wot-binding-templates-10" title= "Reference 2">
+(2)
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-consumed-thing" aria-label= "Links in this document to definition: Consumed Thing">
+<div>
+<a class="self-link" href="#dfn-consumed-thing" aria-label= "Permalink for definition: Consumed Thing. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-consumed-thing-1" title= "§ 6.10 WoT System Components and their Interconnectivity">
+§
+6.10
+WoT
+System
+Components
+and
+their
+Interconnectivity
+</a>
+<a href= "#ref-for-dfn-consumed-thing-2" title="Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-consumed-thing-3" title= "Reference 3">
+(3)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumed-thing-4" title= "§ 6.10.1 Direct Communication">
+§
+6.10.1
+Direct
+Communication
+</a>
+<a href="#ref-for-dfn-consumed-thing-5" title="Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-consumed-thing-6" title= "Reference 3">
+(3)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumed-thing-7" title= "§ 6.10.2 Indirect Communication">
+§
+6.10.2
+Indirect
+Communication
+</a>
+<a href="#ref-for-dfn-consumed-thing-8" title= "Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-consumed-thing-9" title="Reference 3">
+(3)
+</a>
+<a href= "#ref-for-dfn-consumed-thing-10" title="Reference 4">
+(4)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumed-thing-11" title= "§ 8.4 Exposed Thing and Consumed Thing Abstractions">
+§
+8.4
+Exposed
+Thing
+and
+Consumed
+Thing
+Abstractions
+</a>
+<a href= "#ref-for-dfn-consumed-thing-12" title="Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-consumed-thing-13" title= "Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-consumed-thing-14" title="Reference 4">
+(4)
+</a>
+<a href= "#ref-for-dfn-consumed-thing-15" title="Reference 5">
+(5)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumed-thing-16" title= "§ 8.6 Protocol Stack Implementation">
+§
+8.6
+Protocol
+Stack
+Implementation
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumed-thing-17" title= "§ 8.7 System API">
+§
+8.7
+System
+API
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumed-thing-18" title= "§ 9. Example WoT Deployments">
+§
+9.
+Example
+WoT
+Deployments
+</a>
+<a href="#ref-for-dfn-consumed-thing-19" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumed-thing-20" title= "§ 9.1 Thing and Consumer Roles">
+§
+9.1
+Thing
+and
+Consumer
+Roles
+</a>
+<a href="#ref-for-dfn-consumed-thing-21" title= "Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-consumed-thing-22" title="Reference 3">
+(3)
+</a>
+<a href= "#ref-for-dfn-consumed-thing-23" title="Reference 4">
+(4)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumed-thing-24" title= "§ 9.2.2 Consumer and Thing Connected via Intermediaries">
+§
+9.2.2
+Consumer
+and
+Thing
+Connected
+via
+Intermediaries
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumed-thing-25" title= "§ 9.2.2.1 Intermediary Acting as a Proxy">
+§
+9.2.2.1
+Intermediary
+Acting
+as
+a
+Proxy
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-content-type" aria-label= "Links in this document to definition: Content Type">
+<div>
+<a class="self-link" href="#dfn-content-type" aria-label= "Permalink for definition: Content Type. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-content-type-1" title= "§ 7.5 WoT Binding Templates">
+§
+7.5
+WoT
+Binding
+Templates
+</a>
+<a href="#ref-for-dfn-content-type-2" title= "Reference 2">
+(2)
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-consuming-a-thing" aria-label= "Links in this document to definition: Consuming a Thing">
+<div>
+<a class="self-link" href="#dfn-consuming-a-thing" aria-label= "Permalink for definition: Consuming a Thing. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+Not
+referenced
+in
+this
+document.
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-consumer" aria-label= "Links in this document to definition: Consumer">
+<div>
+<a class="self-link" href="#dfn-consumer" aria-label= "Permalink for definition: Consumer. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-consumer-1" title="§ 3. Terminology">
+§
+3.
+Terminology
+</a>
+<a href="#ref-for-dfn-consumer-2" title= "Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-consumer-3" title= "Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-consumer-4" title= "Reference 4">
+(4)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumer-5" title="§ 5.1 Telemetry">
+§
+5.1
+Telemetry
+</a>
+<a href="#ref-for-dfn-consumer-6" title= "Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-consumer-7" title= "Reference 3">
+(3)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumer-8" title= "§ 5.9 Virtual Things">
+§
+5.9
+Virtual
+Things
+</a>
+<a href= "#ref-for-dfn-consumer-9" title="Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumer-10" title= "§ 6. Abstract WoT System Architecture">
+§
+6.
+Abstract
+WoT
+System
+Architecture
+</a>
+<a href="#ref-for-dfn-consumer-11" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumer-12" title= "§ 6.1 Fundamental Concepts">
+§
+6.1
+Fundamental
+Concepts
+</a>
+<a href="#ref-for-dfn-consumer-13" title="Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-consumer-14" title="Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-consumer-16" title="Reference 4">
+(4)
+</a>
+<a href="#ref-for-dfn-consumer-17" title="Reference 5">
+(5)
+</a>
+<a href="#ref-for-dfn-consumer-18" title="Reference 6">
+(6)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumer-15" title= "§ 6.1.1.1 Thing Descriptions">
+§
+6.1.1.1
+Thing
+Descriptions
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumer-19" title="§ 6.2 Affordances">
+§
+6.2
+Affordances
+</a>
+<a href="#ref-for-dfn-consumer-20" title= "Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-consumer-21" title= "Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-consumer-22" title= "Reference 4">
+(4)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumer-23" title="§ 6.3 Web Thing">
+§
+6.3
+Web
+Thing
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumer-24" title="§ 6.4 Lifecycle">
+§
+6.4
+Lifecycle
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumer-25" title= "§ 6.4.1 Simple System Lifecycle">
+§
+6.4.1
+Simple
+System
+Lifecycle
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumer-26" title= "§ 6.5 Interaction Model">
+§
+6.5
+Interaction
+Model
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumer-27" title="§ 6.5.3 Events">
+§
+6.5.3
+Events
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumer-28" title="§ 6.6.1 Links">
+§
+6.6.1
+Links
+</a>
+<a href="#ref-for-dfn-consumer-29" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumer-30" title="§ 6.6.2 Forms">
+§
+6.6.2
+Forms
+</a>
+<a href="#ref-for-dfn-consumer-31" title= "Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-consumer-32" title= "Reference 3">
+(3)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumer-33" title= "§ 6.7 Protocol Bindings">
+§
+6.7
+Protocol
+Bindings
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumer-34" title= "§ 6.7.1 Hypermedia-driven">
+§
+6.7.1
+Hypermedia-driven
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumer-35" title= "§ 6.10 WoT System Components and their Interconnectivity">
+§
+6.10
+WoT
+System
+Components
+and
+their
+Interconnectivity
+</a>
+<a href= "#ref-for-dfn-consumer-36" title="Reference 2">
+(2)
+</a>
+<a href= "#ref-for-dfn-consumer-37" title="Reference 3">
+(3)
+</a>
+<a href= "#ref-for-dfn-consumer-38" title="Reference 4">
+(4)
+</a>
+<a href= "#ref-for-dfn-consumer-39" title="Reference 5">
+(5)
+</a>
+<a href= "#ref-for-dfn-consumer-40" title="Reference 6">
+(6)
+</a>
+<a href= "#ref-for-dfn-consumer-41" title="Reference 7">
+(7)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumer-42" title= "§ 6.10.1 Direct Communication">
+§
+6.10.1
+Direct
+Communication
+</a>
+<a href="#ref-for-dfn-consumer-43" title="Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-consumer-44" title="Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-consumer-45" title="Reference 4">
+(4)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumer-46" title= "§ 6.10.2 Indirect Communication">
+§
+6.10.2
+Indirect
+Communication
+</a>
+<a href="#ref-for-dfn-consumer-47" title= "Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-consumer-48" title= "Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-consumer-49" title= "Reference 4">
+(4)
+</a>
+<a href="#ref-for-dfn-consumer-50" title= "Reference 5">
+(5)
+</a>
+<a href="#ref-for-dfn-consumer-51" title= "Reference 6">
+(6)
+</a>
+<a href="#ref-for-dfn-consumer-52" title= "Reference 7">
+(7)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumer-53" title= "§ 7.5 WoT Binding Templates">
+§
+7.5
+WoT
+Binding
+Templates
+</a>
+<a href="#ref-for-dfn-consumer-54" title="Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumer-55" title= "§ 7.6 WoT Scripting API">
+§
+7.6
+WoT
+Scripting
+API
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumer-56" title= "§ 8. Abstract Servient Architecture">
+§
+8.
+Abstract
+Servient
+Architecture
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumer-57" title= "§ 8.1 Behavior Implementation">
+§
+8.1
+Behavior
+Implementation
+</a>
+<a href="#ref-for-dfn-consumer-58" title="Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-consumer-59" title="Reference 3">
+(3)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumer-60" title= "§ 8.4 Exposed Thing and Consumed Thing Abstractions">
+§
+8.4
+Exposed
+Thing
+and
+Consumed
+Thing
+Abstractions
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumer-61" title= "§ 8.6 Protocol Stack Implementation">
+§
+8.6
+Protocol
+Stack
+Implementation
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumer-62" title= "§ 9. Example WoT Deployments">
+§
+9.
+Example
+WoT
+Deployments
+</a>
+<a href="#ref-for-dfn-consumer-63" title="Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-consumer-64" title="Reference 3">
+(3)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumer-65" title= "§ 9.1 Thing and Consumer Roles">
+§
+9.1
+Thing
+and
+Consumer
+Roles
+</a>
+<a href="#ref-for-dfn-consumer-66" title="Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-consumer-67" title="Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-consumer-68" title="Reference 4">
+(4)
+</a>
+<a href="#ref-for-dfn-consumer-69" title="Reference 5">
+(5)
+</a>
+<a href="#ref-for-dfn-consumer-70" title="Reference 6">
+(6)
+</a>
+<a href="#ref-for-dfn-consumer-71" title="Reference 7">
+(7)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumer-72" title= "§ 9.2.1 Consumer and Thing on the Same Network">
+§
+9.2.1
+Consumer
+and
+Thing
+on
+the
+Same
+Network
+</a>
+<a href= "#ref-for-dfn-consumer-73" title="Reference 2">
+(2)
+</a>
+<a href= "#ref-for-dfn-consumer-74" title="Reference 3">
+(3)
+</a>
+<a href= "#ref-for-dfn-consumer-75" title="Reference 4">
+(4)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumer-76" title= "§ 9.2.2 Consumer and Thing Connected via Intermediaries">
+§
+9.2.2
+Consumer
+and
+Thing
+Connected
+via
+Intermediaries
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumer-77" title= "§ 9.2.2.1 Intermediary Acting as a Proxy">
+§
+9.2.2.1
+Intermediary
+Acting
+as
+a
+Proxy
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumer-78" title= "§ 9.2.2.2 Intermediary Acting as a Digital Twin">
+§
+9.2.2.2
+Intermediary
+Acting
+as
+a
+Digital
+Twin
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumer-79" title= "§ 9.2.3 Devices in a Local Network Controlled from a Cloud Service">
+§
+9.2.3
+Devices
+in
+a
+Local
+Network
+Controlled
+from
+a
+Cloud
+Service
+</a>
+<a href="#ref-for-dfn-consumer-80" title= "Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-consumer-81" title= "Reference 3">
+(3)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumer-82" title= "§ 9.2.4 Discovery Using a Thing Description Directory">
+§
+9.2.4
+Discovery
+Using
+a
+Thing
+Description
+Directory
+</a>
+<a href= "#ref-for-dfn-consumer-83" title="Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumer-84" title= "§ 9.2.5 Service-to-Service Connections Across Multiple Domains">
+§
+9.2.5
+Service-to-Service
+Connections
+Across
+Multiple
+Domains
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-consumer-85" title= "§ 9.2.5.1 Connection Through Thing Description Directory Synchronization">
+§
+9.2.5.1
+Connection
+Through
+Thing
+Description
+Directory
+Synchronization
+</a>
+<a href="#ref-for-dfn-consumer-86" title= "Reference 2">
+(2)
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-data-schema" aria-label= "Links in this document to definition: Data Schema">
+<div>
+<a class="self-link" href="#dfn-data-schema" aria-label= "Permalink for definition: Data Schema. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-data-schema-1" title= "§ 6.5.1 Properties">
+§
+6.5.1
+Properties
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-data-schema-2" title="§ 6.5.2 Actions">
+§
+6.5.2
+Actions
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-data-schema-3" title="§ 6.5.3 Events">
+§
+6.5.3
+Events
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-data-schema-4" title= "§ 6.8 Media Types">
+§
+6.8
+Media
+Types
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-device" aria-label= "Links in this document to definition: Device">
+<div>
+<a class="self-link" href="#dfn-device" aria-label= "Permalink for definition: Device. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-device-1" title="§ 3. Terminology">
+§
+3.
+Terminology
+</a>
+<a href="#ref-for-dfn-device-2" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-device-3" title="§ 6.4 Lifecycle">
+§
+6.4
+Lifecycle
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-device-4" title= "§ 6.4.1 Simple System Lifecycle">
+§
+6.4.1
+Simple
+System
+Lifecycle
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-device-5" title="§ 7.2 Thing Model">
+§
+7.2
+Thing
+Model
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-digital-twin" aria-label= "Links in this document to definition: Digital Twin">
+<div>
+<a class="self-link" href="#dfn-digital-twin" aria-label= "Permalink for definition: Digital Twin. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-digital-twin-1" title= "§ 3. Terminology">
+§
+3.
+Terminology
+</a>
+<a href= "#ref-for-dfn-digital-twin-2" title="Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-digital-twin-3" title= "§ 5.9 Virtual Things">
+§
+5.9
+Virtual
+Things
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-digital-twin-4" title= "§ 9.2.2 Consumer and Thing Connected via Intermediaries">
+§
+9.2.2
+Consumer
+and
+Thing
+Connected
+via
+Intermediaries
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-digital-twin-5" title= "§ 9.2.2.2 Intermediary Acting as a Digital Twin">
+§
+9.2.2.2
+Intermediary
+Acting
+as
+a
+Digital
+Twin
+</a>
+<a href= "#ref-for-dfn-digital-twin-6" title="Reference 2">
+(2)
+</a>
+<a href= "#ref-for-dfn-digital-twin-7" title="Reference 3">
+(3)
+</a>
+<a href= "#ref-for-dfn-digital-twin-8" title="Reference 4">
+(4)
+</a>
+<a href= "#ref-for-dfn-digital-twin-9" title="Reference 5">
+(5)
+</a>
+<a href= "#ref-for-dfn-digital-twin-10" title="Reference 6">
+(6)
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-directory" aria-label= "Links in this document to definition: Directory">
+<div>
+<a class="self-link" href="#dfn-directory" aria-label= "Permalink for definition: Directory. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+Not
+referenced
+in
+this
+document.
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-wot-discovery" aria-label= "Links in this document to definition: Discovery">
+<div>
+<a class="self-link" href="#dfn-wot-discovery" aria-label= "Permalink for definition: Discovery. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-wot-discovery-1" title= "§ 3. Terminology">
+§
+3.
+Terminology
+</a>
+<a href= "#ref-for-dfn-wot-discovery-2" title="Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-discovery-3" title= "§ 6.4.3 Thing Lifecycle">
+§
+6.4.3
+Thing
+Lifecycle
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-discovery-4" title="§ 6.6.1 Links">
+§
+6.6.1
+Links
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-discovery-5" title= "§ 7. WoT Building Blocks">
+§
+7.
+WoT
+Building
+Blocks
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-discovery-6" title= "§ 7.4 WoT Discovery">
+§
+7.4
+WoT
+Discovery
+</a>
+<a href= "#ref-for-dfn-wot-discovery-7" title="Reference 2">
+(2)
+</a>
+<a href= "#ref-for-dfn-wot-discovery-8" title="Reference 3">
+(3)
+</a>
+<a href= "#ref-for-dfn-wot-discovery-9" title="Reference 4">
+(4)
+</a>
+<a href= "#ref-for-dfn-wot-discovery-10" title="Reference 5">
+(5)
+</a>
+<a href="#ref-for-dfn-wot-discovery-14" title= "Reference 6">
+(6)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-discovery-11" title= "§ 7.4.1 Introduction Mechanisms">
+§
+7.4.1
+Introduction
+Mechanisms
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-discovery-12" title= "§ 7.4.2 Exploration Mechanisms">
+§
+7.4.2
+Exploration
+Mechanisms
+</a>
+<a href="#ref-for-dfn-wot-discovery-13" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-discovery-15" title= "§ 9.1 Thing and Consumer Roles">
+§
+9.1
+Thing
+and
+Consumer
+Roles
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-discovery-16" title= "§ 11.1.1 Thing Description Personally Identifiable Information Risk">
+§
+11.1.1
+Thing
+Description
+Personally
+Identifiable
+Information
+Risk
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-wot-discoverer" aria-label= "Links in this document to definition: Discoverer">
+<div>
+<a class="self-link" href="#dfn-wot-discoverer" aria-label= "Permalink for definition: Discoverer. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+Not
+referenced
+in
+this
+document.
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-domain-specific-vocabulary" aria-label= "Links in this document to definition: Domain-specific Vocabulary">
+<div>
+<a class="self-link" href="#dfn-domain-specific-vocabulary" aria-label= "Permalink for definition: Domain-specific Vocabulary. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-domain-specific-vocabulary-1" title= "§ 7.1 WoT Thing Description">
+§
+7.1
+WoT
+Thing
+Description
+</a>
+<a href="#ref-for-dfn-domain-specific-vocabulary-2" title= "Reference 2">
+(2)
+</a>
+<a href= "#ref-for-dfn-domain-specific-vocabulary-3" title= "Reference 3">
+(3)
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-edge-device" aria-label= "Links in this document to definition: Edge Device">
+<div>
+<a class="self-link" href="#dfn-edge-device" aria-label= "Permalink for definition: Edge Device. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-edge-device-1" title= "§ 6.1 Fundamental Concepts">
+§
+6.1
+Fundamental
+Concepts
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-wot-enriched-thing-description" aria-label= "Links in this document to definition: Enriched TD">
+<div>
+<a class="self-link" href= "#dfn-wot-enriched-thing-description" aria-label= "Permalink for definition: Enriched TD. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+Not
+referenced
+in
+this
+document.
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-event" aria-label= "Links in this document to definition: Event">
+<div>
+<a class="self-link" href="#dfn-event" aria-label= "Permalink for definition: Event. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-event-1" title="§ 3. Terminology">
+§
+3.
+Terminology
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-event-2" title="§ 6.1.1.2 Thing Models">
+§
+6.1.1.2
+Thing
+Models
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-event-3" title="§ 6.2 Affordances">
+§
+6.2
+Affordances
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-event-4" title= "§ 6.5 Interaction Model">
+§
+6.5
+Interaction
+Model
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-event-5" title="§ 6.5.3 Events">
+§
+6.5.3
+Events
+</a>
+<a href="#ref-for-dfn-event-6" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-event-7" title="§ 7.2 Thing Model">
+§
+7.2
+Thing
+Model
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-event-8" title= "§ 7.6 WoT Scripting API">
+§
+7.6
+WoT
+Scripting
+API
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-event-9" title= "§ 9.2.2.2 Intermediary Acting as a Digital Twin">
+§
+9.2.2.2
+Intermediary
+Acting
+as
+a
+Digital
+Twin
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-wot-exploration" aria-label= "Links in this document to definition: Exploration">
+<div>
+<a class="self-link" href="#dfn-wot-exploration" aria-label= "Permalink for definition: Exploration. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-wot-exploration-1" title= "§ 7.4 WoT Discovery">
+§
+7.4
+WoT
+Discovery
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-exploration-2" title= "§ 7.4.2 Exploration Mechanisms">
+§
+7.4.2
+Exploration
+Mechanisms
+</a>
+<a href="#ref-for-dfn-wot-exploration-3" title= "Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-wot-exploration-4" title="Reference 3">
+(3)
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-exposed-thing" aria-label= "Links in this document to definition: Exposed Thing">
+<div>
+<a class="self-link" href="#dfn-exposed-thing" aria-label= "Permalink for definition: Exposed Thing. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-exposed-thing-1" title= "§ 3. Terminology">
+§
+3.
+Terminology
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-exposed-thing-2" title= "§ 6.10 WoT System Components and their Interconnectivity">
+§
+6.10
+WoT
+System
+Components
+and
+their
+Interconnectivity
+</a>
+<a href= "#ref-for-dfn-exposed-thing-3" title="Reference 2">
+(2)
+</a>
+<a href= "#ref-for-dfn-exposed-thing-4" title="Reference 3">
+(3)
+</a>
+<a href= "#ref-for-dfn-exposed-thing-5" title="Reference 4">
+(4)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-exposed-thing-6" title= "§ 6.10.1 Direct Communication">
+§
+6.10.1
+Direct
+Communication
+</a>
+<a href="#ref-for-dfn-exposed-thing-7" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-exposed-thing-8" title= "§ 6.10.2 Indirect Communication">
+§
+6.10.2
+Indirect
+Communication
+</a>
+<a href="#ref-for-dfn-exposed-thing-9" title= "Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-exposed-thing-10" title="Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-exposed-thing-11" title="Reference 4">
+(4)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-exposed-thing-12" title= "§ 8.4 Exposed Thing and Consumed Thing Abstractions">
+§
+8.4
+Exposed
+Thing
+and
+Consumed
+Thing
+Abstractions
+</a>
+<a href= "#ref-for-dfn-exposed-thing-13" title="Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-exposed-thing-14" title= "Reference 3">
+(3)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-exposed-thing-15" title= "§ 8.6 Protocol Stack Implementation">
+§
+8.6
+Protocol
+Stack
+Implementation
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-exposed-thing-16" title= "§ 9. Example WoT Deployments">
+§
+9.
+Example
+WoT
+Deployments
+</a>
+<a href="#ref-for-dfn-exposed-thing-17" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-exposed-thing-18" title= "§ 9.1 Thing and Consumer Roles">
+§
+9.1
+Thing
+and
+Consumer
+Roles
+</a>
+<a href="#ref-for-dfn-exposed-thing-19" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-exposed-thing-20" title= "§ 9.2.2 Consumer and Thing Connected via Intermediaries">
+§
+9.2.2
+Consumer
+and
+Thing
+Connected
+via
+Intermediaries
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-exposed-thing-21" title= "§ 9.2.2.1 Intermediary Acting as a Proxy">
+§
+9.2.2.1
+Intermediary
+Acting
+as
+a
+Proxy
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-exposed-thing-22" title= "§ 9.2.3 Devices in a Local Network Controlled from a Cloud Service">
+§
+9.2.3
+Devices
+in
+a
+Local
+Network
+Controlled
+from
+a
+Cloud
+Service
+</a>
+<a href="#ref-for-dfn-exposed-thing-23" title= "Reference 2">
+(2)
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-exposing-a-thing" aria-label= "Links in this document to definition: Exposing a Thing">
+<div>
+<a class="self-link" href="#dfn-exposing-a-thing" aria-label= "Permalink for definition: Exposing a Thing. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+Not
+referenced
+in
+this
+document.
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-hypermedia-control" aria-label= "Links in this document to definition: Hypermedia Control">
+<div>
+<a class="self-link" href="#dfn-hypermedia-control" aria-label="Permalink for definition: Hypermedia Control. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-hypermedia-control-1" title= "§ 3. Terminology">
+§
+3.
+Terminology
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-hypermedia-control-2" title= "§ 6.6 Hypermedia Controls">
+§
+6.6
+Hypermedia
+Controls
+</a>
+<a href= "#ref-for-dfn-hypermedia-control-3" title="Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-hypermedia-control-4" title= "Reference 3">
+(3)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-hypermedia-control-5" title= "§ 6.6.2 Forms">
+§
+6.6.2
+Forms
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-hypermedia-control-6" title= "§ 6.7.1 Hypermedia-driven">
+§
+6.7.1
+Hypermedia-driven
+</a>
+<a href= "#ref-for-dfn-hypermedia-control-7" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-hypermedia-control-8" title= "§ 7.1 WoT Thing Description">
+§
+7.1
+WoT
+Thing
+Description
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-interaction-affordance" aria-label= "Links in this document to definition: Interaction Affordance">
+<div>
+<a class="self-link" href="#dfn-interaction-affordance" aria-label= "Permalink for definition: Interaction Affordance. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-interaction-affordance-1" title= "§ 3. Terminology">
+§
+3.
+Terminology
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-interaction-affordance-2" title= "§ 6.2 Affordances">
+§
+6.2
+Affordances
+</a>
+<a href= "#ref-for-dfn-interaction-affordance-3" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-interaction-affordance-4" title= "§ 6.3 Web Thing">
+§
+6.3
+Web
+Thing
+</a>
+<a href= "#ref-for-dfn-interaction-affordance-5" title="Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-interaction-affordance-6" title= "Reference 3">
+(3)
+</a>
+<a href= "#ref-for-dfn-interaction-affordance-7" title="Reference 4">
+(4)
+</a>
+<a href="#ref-for-dfn-interaction-affordance-8" title= "Reference 5">
+(5)
+</a>
+<a href= "#ref-for-dfn-interaction-affordance-9" title= "Reference 6">
+(6)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-interaction-affordance-10" title= "§ 6.5 Interaction Model">
+§
+6.5
+Interaction
+Model
+</a>
+<a href= "#ref-for-dfn-interaction-affordance-11" title= "Reference 2">
+(2)
+</a>
+<a href= "#ref-for-dfn-interaction-affordance-12" title= "Reference 3">
+(3)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-interaction-affordance-13" title= "§ 6.5.1 Properties">
+§
+6.5.1
+Properties
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-interaction-affordance-14" title= "§ 6.5.2 Actions">
+§
+6.5.2
+Actions
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-interaction-affordance-15" title= "§ 6.5.3 Events">
+§
+6.5.3
+Events
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-interaction-affordance-16" title= "§ 6.7 Protocol Bindings">
+§
+6.7
+Protocol
+Bindings
+</a>
+<a href= "#ref-for-dfn-interaction-affordance-17" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-interaction-affordance-18" title= "§ 6.7.1 Hypermedia-driven">
+§
+6.7.1
+Hypermedia-driven
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-interaction-affordance-19" title= "§ 6.7.2 URIs">
+§
+6.7.2
+URIs
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-interaction-affordance-20" title= "§ 6.10.1 Direct Communication">
+§
+6.10.1
+Direct
+Communication
+</a>
+<a href="#ref-for-dfn-interaction-affordance-21" title= "Reference 2">
+(2)
+</a>
+<a href= "#ref-for-dfn-interaction-affordance-22" title= "Reference 3">
+(3)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-interaction-affordance-23" title= "§ 6.10.2 Indirect Communication">
+§
+6.10.2
+Indirect
+Communication
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-interaction-affordance-24" title= "§ 7.1 WoT Thing Description">
+§
+7.1
+WoT
+Thing
+Description
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-interaction-affordance-25" title= "§ 7.5 WoT Binding Templates">
+§
+7.5
+WoT
+Binding
+Templates
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-interaction-affordance-26" title= "§ 7.6 WoT Scripting API">
+§
+7.6
+WoT
+Scripting
+API
+</a>
+<a href= "#ref-for-dfn-interaction-affordance-27" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-interaction-affordance-28" title= "§ 8.1 Behavior Implementation">
+§
+8.1
+Behavior
+Implementation
+</a>
+<a href="#ref-for-dfn-interaction-affordance-29" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-interaction-affordance-30" title= "§ 8.4 Exposed Thing and Consumed Thing Abstractions">
+§
+8.4
+Exposed
+Thing
+and
+Consumed
+Thing
+Abstractions
+</a>
+<a href= "#ref-for-dfn-interaction-affordance-31" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-interaction-affordance-32" title= "§ 9.1 Thing and Consumer Roles">
+§
+9.1
+Thing
+and
+Consumer
+Roles
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-interaction-affordance-33" title= "§ 9.2.2.1 Intermediary Acting as a Proxy">
+§
+9.2.2.1
+Intermediary
+Acting
+as
+a
+Proxy
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-interaction-affordance-34" title= "§ 9.2.3 Devices in a Local Network Controlled from a Cloud Service">
+§
+9.2.3
+Devices
+in
+a
+Local
+Network
+Controlled
+from
+a
+Cloud
+Service
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-interaction-model" aria-label= "Links in this document to definition: Interaction Model">
+<div>
+<a class="self-link" href="#dfn-interaction-model" aria-label= "Permalink for definition: Interaction Model. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-interaction-model-1" title= "§ 6.5 Interaction Model">
+§
+6.5
+Interaction
+Model
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-interaction-model-2" title= "§ 6.6.2 Forms">
+§
+6.6.2
+Forms
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-interaction-model-3" title= "§ 8.2 WoT Runtime">
+§
+8.2
+WoT
+Runtime
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-intermediary" aria-label= "Links in this document to definition: Intermediary">
+<div>
+<a class="self-link" href="#dfn-intermediary" aria-label= "Permalink for definition: Intermediary. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-intermediary-1" title= "§ 3. Terminology">
+§
+3.
+Terminology
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-intermediary-2" title= "§ 5.9 Virtual Things">
+§
+5.9
+Virtual
+Things
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-intermediary-3" title= "§ 6. Abstract WoT System Architecture">
+§
+6.
+Abstract
+WoT
+System
+Architecture
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-intermediary-4" title= "§ 6.1 Fundamental Concepts">
+§
+6.1
+Fundamental
+Concepts
+</a>
+<a href="#ref-for-dfn-intermediary-5" title="Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-intermediary-6" title="Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-intermediary-7" title="Reference 4">
+(4)
+</a>
+<a href="#ref-for-dfn-intermediary-8" title="Reference 5">
+(5)
+</a>
+<a href="#ref-for-dfn-intermediary-9" title= "Reference 6">
+(6)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-intermediary-10" title= "§ 6.4 Lifecycle">
+§
+6.4
+Lifecycle
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-intermediary-11" title= "§ 6.10 WoT System Components and their Interconnectivity">
+§
+6.10
+WoT
+System
+Components
+and
+their
+Interconnectivity
+</a>
+<a href= "#ref-for-dfn-intermediary-12" title="Reference 2">
+(2)
+</a>
+<a href= "#ref-for-dfn-intermediary-13" title="Reference 3">
+(3)
+</a>
+<a href= "#ref-for-dfn-intermediary-14" title="Reference 4">
+(4)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-intermediary-15" title= "§ 6.10.2 Indirect Communication">
+§
+6.10.2
+Indirect
+Communication
+</a>
+<a href="#ref-for-dfn-intermediary-16" title= "Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-intermediary-17" title= "Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-intermediary-18" title= "Reference 4">
+(4)
+</a>
+<a href="#ref-for-dfn-intermediary-19" title= "Reference 5">
+(5)
+</a>
+<a href="#ref-for-dfn-intermediary-20" title= "Reference 6">
+(6)
+</a>
+<a href="#ref-for-dfn-intermediary-21" title= "Reference 7">
+(7)
+</a>
+<a href="#ref-for-dfn-intermediary-22" title= "Reference 8">
+(8)
+</a>
+<a href="#ref-for-dfn-intermediary-23" title= "Reference 9">
+(9)
+</a>
+<a href="#ref-for-dfn-intermediary-24" title= "Reference 10">
+(10)
+</a>
+<a href="#ref-for-dfn-intermediary-25" title="Reference 11">
+(11)
+</a>
+<a href= "#ref-for-dfn-intermediary-26" title="Reference 12">
+(12)
+</a>
+<a href="#ref-for-dfn-intermediary-27" title= "Reference 13">
+(13)
+</a>
+<a href="#ref-for-dfn-intermediary-28" title="Reference 14">
+(14)
+</a>
+<a href= "#ref-for-dfn-intermediary-29" title="Reference 15">
+(15)
+</a>
+<a href="#ref-for-dfn-intermediary-30" title= "Reference 16">
+(16)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-intermediary-31" title= "§ 7.6 WoT Scripting API">
+§
+7.6
+WoT
+Scripting
+API
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-intermediary-32" title= "§ 8.1 Behavior Implementation">
+§
+8.1
+Behavior
+Implementation
+</a>
+<a href="#ref-for-dfn-intermediary-33" title="Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-intermediary-34" title= "Reference 3">
+(3)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-intermediary-35" title= "§ 9.1 Thing and Consumer Roles">
+§
+9.1
+Thing
+and
+Consumer
+Roles
+</a>
+<a href="#ref-for-dfn-intermediary-36" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-intermediary-37" title= "§ 9.2.2 Consumer and Thing Connected via Intermediaries">
+§
+9.2.2
+Consumer
+and
+Thing
+Connected
+via
+Intermediaries
+</a>
+<a href= "#ref-for-dfn-intermediary-38" title="Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-intermediary-39" title= "§ 9.2.2.1 Intermediary Acting as a Proxy">
+§
+9.2.2.1
+Intermediary
+Acting
+as
+a
+Proxy
+</a>
+<a href="#ref-for-dfn-intermediary-40" title= "Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-intermediary-41" title= "Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-intermediary-42" title= "Reference 4">
+(4)
+</a>
+<a href="#ref-for-dfn-intermediary-43" title= "Reference 5">
+(5)
+</a>
+<a href="#ref-for-dfn-intermediary-44" title= "Reference 6">
+(6)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-intermediary-45" title= "§ 9.2.2.2 Intermediary Acting as a Digital Twin">
+§
+9.2.2.2
+Intermediary
+Acting
+as
+a
+Digital
+Twin
+</a>
+<a href= "#ref-for-dfn-intermediary-46" title="Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-intermediary-47" title= "§ 9.2.3 Devices in a Local Network Controlled from a Cloud Service">
+§
+9.2.3
+Devices
+in
+a
+Local
+Network
+Controlled
+from
+a
+Cloud
+Service
+</a>
+<a href="#ref-for-dfn-intermediary-48" title= "Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-intermediary-49" title= "Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-intermediary-50" title= "Reference 4">
+(4)
+</a>
+<a href="#ref-for-dfn-intermediary-51" title= "Reference 5">
+(5)
+</a>
+<a href="#ref-for-dfn-intermediary-52" title= "Reference 6">
+(6)
+</a>
+<a href="#ref-for-dfn-intermediary-53" title= "Reference 7">
+(7)
+</a>
+<a href="#ref-for-dfn-intermediary-54" title= "Reference 8">
+(8)
+</a>
+<a href="#ref-for-dfn-intermediary-55" title= "Reference 9">
+(9)
+</a>
+<a href="#ref-for-dfn-intermediary-56" title= "Reference 10">
+(10)
+</a>
+<a href="#ref-for-dfn-intermediary-57" title="Reference 11">
+(11)
+</a>
+<a href= "#ref-for-dfn-intermediary-58" title="Reference 12">
+(12)
+</a>
+<a href="#ref-for-dfn-intermediary-59" title= "Reference 13">
+(13)
+</a>
+<a href="#ref-for-dfn-intermediary-60" title="Reference 14">
+(14)
+</a>
+<a href= "#ref-for-dfn-intermediary-61" title="Reference 15">
+(15)
+</a>
+<a href="#ref-for-dfn-intermediary-62" title= "Reference 16">
+(16)
+</a>
+<a href="#ref-for-dfn-intermediary-63" title="Reference 17">
+(17)
+</a>
+<a href= "#ref-for-dfn-intermediary-64" title="Reference 18">
+(18)
+</a>
+<a href="#ref-for-dfn-intermediary-65" title= "Reference 19">
+(19)
+</a>
+<a href="#ref-for-dfn-intermediary-66" title="Reference 20">
+(20)
+</a>
+<a href= "#ref-for-dfn-intermediary-67" title="Reference 21">
+(21)
+</a>
+<a href="#ref-for-dfn-intermediary-68" title= "Reference 22">
+(22)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-intermediary-69" title= "§ 9.2.4 Discovery Using a Thing Description Directory">
+§
+9.2.4
+Discovery
+Using
+a
+Thing
+Description
+Directory
+</a>
+<a href= "#ref-for-dfn-intermediary-70" title="Reference 2">
+(2)
+</a>
+<a href= "#ref-for-dfn-intermediary-71" title="Reference 3">
+(3)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-intermediary-72" title= "§ 9.2.5.1 Connection Through Thing Description Directory Synchronization">
+§
+9.2.5.1
+Connection
+Through
+Thing
+Description
+Directory
+Synchronization
+</a>
+<a href="#ref-for-dfn-intermediary-73" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-intermediary-74" title= "§ 9.2.5.2 Connection Through Proxy Synchronization">
+§
+9.2.5.2
+Connection
+Through
+Proxy
+Synchronization
+</a>
+<a href= "#ref-for-dfn-intermediary-75" title="Reference 2">
+(2)
+</a>
+<a href= "#ref-for-dfn-intermediary-76" title="Reference 3">
+(3)
+</a>
+<a href= "#ref-for-dfn-intermediary-77" title="Reference 4">
+(4)
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-wot-introduction" aria-label= "Links in this document to definition: Introduction">
+<div>
+<a class="self-link" href="#dfn-wot-introduction" aria-label= "Permalink for definition: Introduction. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-wot-introduction-1" title= "§ 7.4 WoT Discovery">
+§
+7.4
+WoT
+Discovery
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-introduction-2" title= "§ 7.4.1 Introduction Mechanisms">
+§
+7.4.1
+Introduction
+Mechanisms
+</a>
+<a href="#ref-for-dfn-wot-introduction-3" title= "Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-wot-introduction-4" title="Reference 3">
+(3)
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-iot-platform" aria-label= "Links in this document to definition: IoT Platform">
+<div>
+<a class="self-link" href="#dfn-iot-platform" aria-label= "Permalink for definition: IoT Platform. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-iot-platform-1" title= "§ 6.1 Fundamental Concepts">
+§
+6.1
+Fundamental
+Concepts
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-iot-platform-2" title= "§ 6.6 Hypermedia Controls">
+§
+6.6
+Hypermedia
+Controls
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-iot-platform-3" title= "§ 7.5 WoT Binding Templates">
+§
+7.5
+WoT
+Binding
+Templates
+</a>
+<a href="#ref-for-dfn-iot-platform-4" title="Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-iot-platform-5" title="Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-iot-platform-6" title= "Reference 4">
+(4)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-iot-platform-7" title= "§ 8.6 Protocol Stack Implementation">
+§
+8.6
+Protocol
+Stack
+Implementation
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-iot-platform-8" title= "§ 10.1.2 Thing Description Communication Metadata Risk">
+§
+10.1.2
+Thing
+Description
+Communication
+Metadata
+Risk
+</a>
+<a href= "#ref-for-dfn-iot-platform-9" title="Reference 2">
+(2)
+</a>
+<a href= "#ref-for-dfn-iot-platform-10" title="Reference 3">
+(3)
+</a>
+<a href= "#ref-for-dfn-iot-platform-11" title="Reference 4">
+(4)
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-metadata" aria-label= "Links in this document to definition: Metadata">
+<div>
+<a class="self-link" href="#dfn-metadata" aria-label= "Permalink for definition: Metadata. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+Not
+referenced
+in
+this
+document.
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-personally-identifiable-information" aria-label= "Links in this document to definition: Personally Identifiable Information (PII)">
+<div>
+<a class="self-link" href= "#dfn-personally-identifiable-information" aria-label= "Permalink for definition: Personally Identifiable Information (PII). Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-personally-identifiable-information-1" title="§ 3. Terminology">
+§
+3.
+Terminology
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-personally-identifiable-information-2" title="§ 10.5 Secure Transport">
+§
+10.5
+Secure
+Transport
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-personally-identifiable-information-3" title="§ 11.1 WoT Thing Description Risks">
+§
+11.1
+WoT
+Thing
+Description
+Risks
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-personally-identifiable-information-4" title= "§ 11.1.1 Thing Description Personally Identifiable Information Risk">
+§
+11.1.1
+Thing
+Description
+Personally
+Identifiable
+Information
+Risk
+</a>
+<a href= "#ref-for-dfn-personally-identifiable-information-5" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-personally-identifiable-information-6" title="§ 11.2 Access to Personally Identifiable Information">
+§
+11.2
+Access
+to
+Personally
+Identifiable
+Information
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-orchestration" aria-label= "Links in this document to definition: Orchestration">
+<div>
+<a class="self-link" href="#dfn-orchestration" aria-label= "Permalink for definition: Orchestration. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+Not
+referenced
+in
+this
+document.
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-partial-td" aria-label= "Links in this document to definition: Partial TD">
+<div>
+<a class="self-link" href="#dfn-partial-td" aria-label= "Permalink for definition: Partial TD. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-partial-td-1" title="§ 3. Terminology">
+§
+3.
+Terminology
+</a>
+<a href="#ref-for-dfn-partial-td-2" title= "Reference 2">
+(2)
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-privacy" aria-label= "Links in this document to definition: Privacy">
+<div>
+<a class="self-link" href="#dfn-privacy" aria-label= "Permalink for definition: Privacy. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+Not
+referenced
+in
+this
+document.
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-private-security-data" aria-label= "Links in this document to definition: Private Security Data">
+<div>
+<a class="self-link" href="#dfn-private-security-data" aria-label= "Permalink for definition: Private Security Data. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-private-security-data-1" title= "§ 6.3 Web Thing">
+§
+6.3
+Web
+Thing
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-private-security-data-2" title= "§ 8.2 WoT Runtime">
+§
+8.2
+WoT
+Runtime
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-private-security-data-3" title= "§ 8.5 Private Security Data">
+§
+8.5
+Private
+Security
+Data
+</a>
+<a href="#ref-for-dfn-private-security-data-4" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-private-security-data-5" title= "§ 10.1.1 Thing Description Private Security Data Risk">
+§
+10.1.1
+Thing
+Description
+Private
+Security
+Data
+Risk
+</a>
+<a href= "#ref-for-dfn-private-security-data-6" title="Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-private-security-data-7" title= "Reference 3">
+(3)
+</a>
+<a href= "#ref-for-dfn-private-security-data-8" title= "Reference 4">
+(4)
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-producer" aria-label= "Links in this document to definition: Producer">
+<div>
+<a class="self-link" href="#dfn-producer" aria-label= "Permalink for definition: Producer. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-producer-1" title= "§ 10.1.1 Thing Description Private Security Data Risk">
+§
+10.1.1
+Thing
+Description
+Private
+Security
+Data
+Risk
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-profile" aria-label= "Links in this document to definition: Profile">
+<div>
+<a class="self-link" href="#dfn-profile" aria-label= "Permalink for definition: Profile. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-profile-1" title="§ 3. Terminology">
+§
+3.
+Terminology
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-property" aria-label= "Links in this document to definition: Property">
+<div>
+<a class="self-link" href="#dfn-property" aria-label= "Permalink for definition: Property. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-property-1" title="§ 3. Terminology">
+§
+3.
+Terminology
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-property-2" title= "§ 6.1.1.2 Thing Models">
+§
+6.1.1.2
+Thing
+Models
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-property-3" title="§ 6.2 Affordances">
+§
+6.2
+Affordances
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-property-4" title= "§ 6.5 Interaction Model">
+§
+6.5
+Interaction
+Model
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-property-5" title="§ 6.5.1 Properties">
+§
+6.5.1
+Properties
+</a>
+<a href="#ref-for-dfn-property-6" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-property-7" title="§ 7.2 Thing Model">
+§
+7.2
+Thing
+Model
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-property-8" title= "§ 7.6 WoT Scripting API">
+§
+7.6
+WoT
+Scripting
+API
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-wot-protocol-binding" aria-label= "Links in this document to definition: Protocol Binding">
+<div>
+<a class="self-link" href="#dfn-wot-protocol-binding" aria-label= "Permalink for definition: Protocol Binding. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-wot-protocol-binding-1" title= "§ 6.3 Web Thing">
+§
+6.3
+Web
+Thing
+</a>
+<a href= "#ref-for-dfn-wot-protocol-binding-2" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-protocol-binding-3" title= "§ 6.7 Protocol Bindings">
+§
+6.7
+Protocol
+Bindings
+</a>
+<a href= "#ref-for-dfn-wot-protocol-binding-4" title="Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-wot-protocol-binding-5" title= "Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-wot-protocol-binding-6" title="Reference 4">
+(4)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-protocol-binding-7" title= "§ 6.7.1 Hypermedia-driven">
+§
+6.7.1
+Hypermedia-driven
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-protocol-binding-8" title= "§ 6.10 WoT System Components and their Interconnectivity">
+§
+6.10
+WoT
+System
+Components
+and
+their
+Interconnectivity
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-protocol-binding-9" title= "§ 7.1 WoT Thing Description">
+§
+7.1
+WoT
+Thing
+Description
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-protocol-binding-10" title= "§ 7.5 WoT Binding Templates">
+§
+7.5
+WoT
+Binding
+Templates
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-protocol-binding-11" title= "§ 8. Abstract Servient Architecture">
+§
+8.
+Abstract
+Servient
+Architecture
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-protocol-binding-12" title= "§ 8.2 WoT Runtime">
+§
+8.2
+WoT
+Runtime
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-protocol-binding-13" title= "§ 8.5 Private Security Data">
+§
+8.5
+Private
+Security
+Data
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-protocol-binding-14" title= "§ 8.6 Protocol Stack Implementation">
+§
+8.6
+Protocol
+Stack
+Implementation
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-protocol-binding-15" title= "§ 8.8.2 Thing Description for Existing Devices">
+§
+8.8.2
+Thing
+Description
+for
+Existing
+Devices
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-protocol-binding-16" title= "§ 9.2.2.1 Intermediary Acting as a Proxy">
+§
+9.2.2.1
+Intermediary
+Acting
+as
+a
+Proxy
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-protocol-binding-17" title= "§ 9.2.4 Discovery Using a Thing Description Directory">
+§
+9.2.4
+Discovery
+Using
+a
+Thing
+Description
+Directory
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-public-security-metadata" aria-label= "Links in this document to definition: Public Security Metadata">
+<div>
+<a class="self-link" href="#dfn-public-security-metadata" aria-label= "Permalink for definition: Public Security Metadata. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-public-security-metadata-1" title= "§ 6.3 Web Thing">
+§
+6.3
+Web
+Thing
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-public-security-metadata-2" title= "§ 7.1 WoT Thing Description">
+§
+7.1
+WoT
+Thing
+Description
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-public-security-metadata-3" title= "§ 7.7 WoT Security and Privacy Guidelines">
+§
+7.7
+WoT
+Security
+and
+Privacy
+Guidelines
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-public-security-metadata-4" title= "§ 9.2.2.1 Intermediary Acting as a Proxy">
+§
+9.2.2.1
+Intermediary
+Acting
+as
+a
+Proxy
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-public-security-metadata-5" title= "§ 9.2.4 Discovery Using a Thing Description Directory">
+§
+9.2.4
+Discovery
+Using
+a
+Thing
+Description
+Directory
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-public-security-metadata-6" title= "§ 10.1.1 Thing Description Private Security Data Risk">
+§
+10.1.1
+Thing
+Description
+Private
+Security
+Data
+Risk
+</a>
+<a href= "#ref-for-dfn-public-security-metadata-7" title= "Reference 2">
+(2)
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-wot-registrant" aria-label= "Links in this document to definition: Registrant">
+<div>
+<a class="self-link" href="#dfn-wot-registrant" aria-label= "Permalink for definition: Registrant. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+Not
+referenced
+in
+this
+document.
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-security" aria-label= "Links in this document to definition: Security">
+<div>
+<a class="self-link" href="#dfn-security" aria-label= "Permalink for definition: Security. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-security-1" title="§ 3. Terminology">
+§
+3.
+Terminology
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-security-configuration" aria-label= "Links in this document to definition: Security Configuration">
+<div>
+<a class="self-link" href="#dfn-security-configuration" aria-label= "Permalink for definition: Security Configuration. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-security-configuration-1" title= "§ 3. Terminology">
+§
+3.
+Terminology
+</a>
+<a href= "#ref-for-dfn-security-configuration-2" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-security-configuration-3" title= "§ 6.3 Web Thing">
+§
+6.3
+Web
+Thing
+</a>
+<a href= "#ref-for-dfn-security-configuration-4" title= "Reference 2">
+(2)
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-service" aria-label= "Links in this document to definition: Service">
+<div>
+<a class="self-link" href="#dfn-service" aria-label= "Permalink for definition: Service. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-service-1" title="§ 3. Terminology">
+§
+3.
+Terminology
+</a>
+<a href="#ref-for-dfn-service-2" title= "Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-service-3" title= "Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-service-4" title= "Reference 4">
+(4)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-service-5" title="§ 5.9 Virtual Things">
+§
+5.9
+Virtual
+Things
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-servient" aria-label= "Links in this document to definition: Servient">
+<div>
+<a class="self-link" href="#dfn-servient" aria-label= "Permalink for definition: Servient. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-servient-1" title= "§ 6.10 WoT System Components and their Interconnectivity">
+§
+6.10
+WoT
+System
+Components
+and
+their
+Interconnectivity
+</a>
+<a href= "#ref-for-dfn-servient-2" title="Reference 2">
+(2)
+</a>
+<a href= "#ref-for-dfn-servient-3" title="Reference 3">
+(3)
+</a>
+<a href= "#ref-for-dfn-servient-4" title="Reference 4">
+(4)
+</a>
+<a href= "#ref-for-dfn-servient-5" title="Reference 5">
+(5)
+</a>
+<a href= "#ref-for-dfn-servient-6" title="Reference 6">
+(6)
+</a>
+<a href= "#ref-for-dfn-servient-7" title="Reference 7">
+(7)
+</a>
+<a href= "#ref-for-dfn-servient-8" title="Reference 8">
+(8)
+</a>
+<a href= "#ref-for-dfn-servient-9" title="Reference 9">
+(9)
+</a>
+<a href= "#ref-for-dfn-servient-10" title="Reference 10">
+(10)
+</a>
+<a href= "#ref-for-dfn-servient-11" title="Reference 11">
+(11)
+</a>
+<a href= "#ref-for-dfn-servient-12" title="Reference 12">
+(12)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-servient-13" title= "§ 6.10.1 Direct Communication">
+§
+6.10.1
+Direct
+Communication
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-servient-14" title= "§ 6.10.2 Indirect Communication">
+§
+6.10.2
+Indirect
+Communication
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-servient-15" title= "§ 8. Abstract Servient Architecture">
+§
+8.
+Abstract
+Servient
+Architecture
+</a>
+<a href="#ref-for-dfn-servient-16" title= "Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-servient-17" title= "Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-servient-18" title= "Reference 4">
+(4)
+</a>
+<a href="#ref-for-dfn-servient-19" title= "Reference 5">
+(5)
+</a>
+<a href="#ref-for-dfn-servient-20" title= "Reference 6">
+(6)
+</a>
+<a href="#ref-for-dfn-servient-21" title= "Reference 7">
+(7)
+</a>
+<a href="#ref-for-dfn-servient-22" title= "Reference 8">
+(8)
+</a>
+<a href="#ref-for-dfn-servient-23" title= "Reference 9">
+(9)
+</a>
+<a href="#ref-for-dfn-servient-24" title= "Reference 10">
+(10)
+</a>
+<a href="#ref-for-dfn-servient-25" title= "Reference 11">
+(11)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-servient-26" title= "§ 8.1 Behavior Implementation">
+§
+8.1
+Behavior
+Implementation
+</a>
+<a href="#ref-for-dfn-servient-27" title="Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-servient-28" title="Reference 3">
+(3)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-servient-29" title="§ 8.2 WoT Runtime">
+§
+8.2
+WoT
+Runtime
+</a>
+<a href="#ref-for-dfn-servient-30" title= "Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-servient-31" title= "Reference 3">
+(3)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-servient-32" title= "§ 8.4 Exposed Thing and Consumed Thing Abstractions">
+§
+8.4
+Exposed
+Thing
+and
+Consumed
+Thing
+Abstractions
+</a>
+<a href= "#ref-for-dfn-servient-33" title="Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-servient-34" title= "§ 8.6 Protocol Stack Implementation">
+§
+8.6
+Protocol
+Stack
+Implementation
+</a>
+<a href="#ref-for-dfn-servient-35" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-servient-36" title="§ 8.7 System API">
+§
+8.7
+System
+API
+</a>
+<a href="#ref-for-dfn-servient-37" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-servient-38" title= "§ 8.8 Alternative Servient and WoT Implementations">
+§
+8.8
+Alternative
+Servient
+and
+WoT
+Implementations
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-servient-39" title= "§ 8.8.1 Native WoT API">
+§
+8.8.1
+Native
+WoT
+API
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-servient-40" title= "§ 9. Example WoT Deployments">
+§
+9.
+Example
+WoT
+Deployments
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-servient-41" title= "§ 9.1 Thing and Consumer Roles">
+§
+9.1
+Thing
+and
+Consumer
+Roles
+</a>
+<a href="#ref-for-dfn-servient-42" title="Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-servient-43" title="Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-servient-44" title="Reference 4">
+(4)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-servient-45" title= "§ 10.2 WoT Scripting API Risks">
+§
+10.2
+WoT
+Scripting
+API
+Risks
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-shadow" aria-label= "Links in this document to definition: Shadow">
+<div>
+<a class="self-link" href="#dfn-shadow" aria-label= "Permalink for definition: Shadow. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-shadow-1" title="§ 3. Terminology">
+§
+3.
+Terminology
+</a>
+<a href="#ref-for-dfn-shadow-2" title= "Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-shadow-3" title= "Reference 3">
+(3)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-shadow-4" title="§ 5.9 Virtual Things">
+§
+5.9
+Virtual
+Things
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-subprotocol" aria-label= "Links in this document to definition: Subprotocol">
+<div>
+<a class="self-link" href="#dfn-subprotocol" aria-label= "Permalink for definition: Subprotocol. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-subprotocol-1" title= "§ 7.5 WoT Binding Templates">
+§
+7.5
+WoT
+Binding
+Templates
+</a>
+<a href="#ref-for-dfn-subprotocol-2" title= "Reference 2">
+(2)
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-system" aria-label= "Links in this document to definition: System">
+<div>
+<a class="self-link" href="#dfn-system" aria-label= "Permalink for definition: System. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+Not
+referenced
+in
+this
+document.
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-td" aria-label= "Links in this document to definition: TD">
+<div>
+<a class="self-link" href="#dfn-td" aria-label= "Permalink for definition: TD. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-td-1" title="§ 3. Terminology">
+§
+3.
+Terminology
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-td-2" title= "§ 6.1 Fundamental Concepts">
+§
+6.1
+Fundamental
+Concepts
+</a>
+<a href="#ref-for-dfn-td-3" title="Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-td-4" title= "§ 6.1.1.1 Thing Descriptions">
+§
+6.1.1.1
+Thing
+Descriptions
+</a>
+<a href="#ref-for-dfn-td-5" title="Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-td-6" title="§ 6.7.1 Hypermedia-driven">
+§
+6.7.1
+Hypermedia-driven
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-td-7" title= "§ 6.10.1 Direct Communication">
+§
+6.10.1
+Direct
+Communication
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-td-8" title= "§ 7.1 WoT Thing Description">
+§
+7.1
+WoT
+Thing
+Description
+</a>
+<a href="#ref-for-dfn-td-9" title="Reference 2">
+(2)
+</a>
+<a href= "#ref-for-dfn-td-10" title="Reference 3">
+(3)
+</a>
+<a href= "#ref-for-dfn-td-11" title="Reference 4">
+(4)
+</a>
+<a href= "#ref-for-dfn-td-12" title="Reference 5">
+(5)
+</a>
+<a href= "#ref-for-dfn-td-13" title="Reference 6">
+(6)
+</a>
+<a href= "#ref-for-dfn-td-14" title="Reference 7">
+(7)
+</a>
+<a href= "#ref-for-dfn-td-15" title="Reference 8">
+(8)
+</a>
+<a href= "#ref-for-dfn-td-16" title="Reference 9">
+(9)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-td-17" title="§ 7.4 WoT Discovery">
+§
+7.4
+WoT
+Discovery
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-td-18" title= "§ 7.4.2 Exploration Mechanisms">
+§
+7.4.2
+Exploration
+Mechanisms
+</a>
+<a href="#ref-for-dfn-td-19" title="Reference 2">
+(2)
+</a>
+<a href= "#ref-for-dfn-td-20" title="Reference 3">
+(3)
+</a>
+<a href= "#ref-for-dfn-td-21" title="Reference 4">
+(4)
+</a>
+<a href= "#ref-for-dfn-td-22" title="Reference 5">
+(5)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-td-23" title= "§ 7.5 WoT Binding Templates">
+§
+7.5
+WoT
+Binding
+Templates
+</a>
+<a href="#ref-for-dfn-td-24" title="Reference 2">
+(2)
+</a>
+<a href= "#ref-for-dfn-td-25" title="Reference 3">
+(3)
+</a>
+<a href= "#ref-for-dfn-td-26" title="Reference 4">
+(4)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-td-27" title= "§ 7.7 WoT Security and Privacy Guidelines">
+§
+7.7
+WoT
+Security
+and
+Privacy
+Guidelines
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-td-28" title= "§ 8.4 Exposed Thing and Consumed Thing Abstractions">
+§
+8.4
+Exposed
+Thing
+and
+Consumed
+Thing
+Abstractions
+</a>
+<a href= "#ref-for-dfn-td-29" title="Reference 2">
+(2)
+</a>
+<a href= "#ref-for-dfn-td-30" title="Reference 3">
+(3)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-td-31" title= "§ 8.8 Alternative Servient and WoT Implementations">
+§
+8.8
+Alternative
+Servient
+and
+WoT
+Implementations
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-td-32" title= "§ 10.1.1 Thing Description Private Security Data Risk">
+§
+10.1.1
+Thing
+Description
+Private
+Security
+Data
+Risk
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-tdd" aria-label= "Links in this document to definition: TDD">
+<div>
+<a class="self-link" href="#dfn-tdd" aria-label= "Permalink for definition: TDD. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-tdd-1" title= "§ 7.4.2 Exploration Mechanisms">
+§
+7.4.2
+Exploration
+Mechanisms
+</a>
+<a href="#ref-for-dfn-tdd-2" title="Reference 2">
+(2)
+</a>
+<a href= "#ref-for-dfn-tdd-3" title="Reference 3">
+(3)
+</a>
+<a href= "#ref-for-dfn-tdd-4" title="Reference 4">
+(4)
+</a>
+<a href= "#ref-for-dfn-tdd-5" title="Reference 5">
+(5)
+</a>
+<a href= "#ref-for-dfn-tdd-6" title="Reference 6">
+(6)
+</a>
+<a href= "#ref-for-dfn-tdd-7" title="Reference 7">
+(7)
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-td-vocabulary" aria-label= "Links in this document to definition: TD Vocabulary">
+<div>
+<a class="self-link" href="#dfn-td-vocabulary" aria-label= "Permalink for definition: TD Vocabulary. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+Not
+referenced
+in
+this
+document.
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-td-context-extension" aria-label= "Links in this document to definition: TD Context Extension">
+<div>
+<a class="self-link" href="#dfn-td-context-extension" aria-label= "Permalink for definition: TD Context Extension. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+Not
+referenced
+in
+this
+document.
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-td-server" aria-label= "Links in this document to definition: TD Server">
+<div>
+<a class="self-link" href="#dfn-td-server" aria-label= "Permalink for definition: TD Server. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+Not
+referenced
+in
+this
+document.
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-thing" aria-label= "Links in this document to definition: Thing">
+<div>
+<a class="self-link" href="#dfn-thing" aria-label= "Permalink for definition: Thing. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-thing-1" title="§ 3. Terminology">
+§
+3.
+Terminology
+</a>
+<a href="#ref-for-dfn-thing-2" title= "Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-thing-3" title= "Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-thing-4" title= "Reference 4">
+(4)
+</a>
+<a href="#ref-for-dfn-thing-5" title= "Reference 5">
+(5)
+</a>
+<a href="#ref-for-dfn-thing-6" title= "Reference 6">
+(6)
+</a>
+<a href="#ref-for-dfn-thing-7" title= "Reference 7">
+(7)
+</a>
+<a href="#ref-for-dfn-thing-8" title= "Reference 8">
+(8)
+</a>
+<a href="#ref-for-dfn-thing-9" title= "Reference 9">
+(9)
+</a>
+<a href="#ref-for-dfn-thing-10" title= "Reference 10">
+(10)
+</a>
+<a href="#ref-for-dfn-thing-11" title= "Reference 11">
+(11)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-12" title="§ 5.1 Telemetry">
+§
+5.1
+Telemetry
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-13" title="§ 5.9 Virtual Things">
+§
+5.9
+Virtual
+Things
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-14" title= "§ 6. Abstract WoT System Architecture">
+§
+6.
+Abstract
+WoT
+System
+Architecture
+</a>
+<a href="#ref-for-dfn-thing-15" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-16" title= "§ 6.1 Fundamental Concepts">
+§
+6.1
+Fundamental
+Concepts
+</a>
+<a href="#ref-for-dfn-thing-17" title="Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-thing-18" title="Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-thing-19" title="Reference 4">
+(4)
+</a>
+<a href="#ref-for-dfn-thing-20" title="Reference 5">
+(5)
+</a>
+<a href="#ref-for-dfn-thing-21" title="Reference 6">
+(6)
+</a>
+<a href="#ref-for-dfn-thing-22" title="Reference 7">
+(7)
+</a>
+<a href="#ref-for-dfn-thing-23" title="Reference 8">
+(8)
+</a>
+<a href="#ref-for-dfn-thing-24" title="Reference 9">
+(9)
+</a>
+<a href="#ref-for-dfn-thing-25" title="Reference 10">
+(10)
+</a>
+<a href="#ref-for-dfn-thing-41" title="Reference 11">
+(11)
+</a>
+<a href="#ref-for-dfn-thing-42" title="Reference 12">
+(12)
+</a>
+<a href="#ref-for-dfn-thing-43" title="Reference 13">
+(13)
+</a>
+<a href="#ref-for-dfn-thing-44" title="Reference 14">
+(14)
+</a>
+<a href="#ref-for-dfn-thing-45" title="Reference 15">
+(15)
+</a>
+<a href="#ref-for-dfn-thing-46" title="Reference 16">
+(16)
+</a>
+<a href="#ref-for-dfn-thing-47" title="Reference 17">
+(17)
+</a>
+<a href="#ref-for-dfn-thing-48" title="Reference 18">
+(18)
+</a>
+<a href="#ref-for-dfn-thing-49" title="Reference 19">
+(19)
+</a>
+<a href="#ref-for-dfn-thing-50" title="Reference 20">
+(20)
+</a>
+<a href="#ref-for-dfn-thing-51" title="Reference 21">
+(21)
+</a>
+<a href="#ref-for-dfn-thing-52" title="Reference 22">
+(22)
+</a>
+<a href="#ref-for-dfn-thing-53" title="Reference 23">
+(23)
+</a>
+<a href="#ref-for-dfn-thing-54" title="Reference 24">
+(24)
+</a>
+<a href="#ref-for-dfn-thing-55" title="Reference 25">
+(25)
+</a>
+<a href="#ref-for-dfn-thing-56" title="Reference 26">
+(26)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-26" title="§ 6.1.1 Metadata">
+§
+6.1.1
+Metadata
+</a>
+<a href="#ref-for-dfn-thing-27" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-28" title= "§ 6.1.1.1 Thing Descriptions">
+§
+6.1.1.1
+Thing
+Descriptions
+</a>
+<a href="#ref-for-dfn-thing-29" title="Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-thing-30" title="Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-thing-31" title="Reference 4">
+(4)
+</a>
+<a href="#ref-for-dfn-thing-32" title="Reference 5">
+(5)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-33" title= "§ 6.1.1.2 Thing Models">
+§
+6.1.1.2
+Thing
+Models
+</a>
+<a href= "#ref-for-dfn-thing-34" title="Reference 2">
+(2)
+</a>
+<a href= "#ref-for-dfn-thing-35" title="Reference 3">
+(3)
+</a>
+<a href= "#ref-for-dfn-thing-36" title="Reference 4">
+(4)
+</a>
+<a href= "#ref-for-dfn-thing-37" title="Reference 5">
+(5)
+</a>
+<a href= "#ref-for-dfn-thing-38" title="Reference 6">
+(6)
+</a>
+<a href= "#ref-for-dfn-thing-39" title="Reference 7">
+(7)
+</a>
+<a href= "#ref-for-dfn-thing-40" title="Reference 8">
+(8)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-57" title="§ 6.2 Affordances">
+§
+6.2
+Affordances
+</a>
+<a href="#ref-for-dfn-thing-58" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-59" title="§ 6.3 Web Thing">
+§
+6.3
+Web
+Thing
+</a>
+<a href="#ref-for-dfn-thing-60" title= "Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-thing-61" title= "Reference 3">
+(3)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-62" title="§ 6.4 Lifecycle">
+§
+6.4
+Lifecycle
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-63" title= "§ 6.5 Interaction Model">
+§
+6.5
+Interaction
+Model
+</a>
+<a href= "#ref-for-dfn-thing-64" title="Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-65" title="§ 6.5.1 Properties">
+§
+6.5.1
+Properties
+</a>
+<a href="#ref-for-dfn-thing-66" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-67" title="§ 6.5.2 Actions">
+§
+6.5.2
+Actions
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-68" title="§ 6.5.3 Events">
+§
+6.5.3
+Events
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-69" title="§ 6.6.1 Links">
+§
+6.6.1
+Links
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-70" title= "§ 6.7.1 Hypermedia-driven">
+§
+6.7.1
+Hypermedia-driven
+</a>
+<a href= "#ref-for-dfn-thing-71" title="Reference 2">
+(2)
+</a>
+<a href= "#ref-for-dfn-thing-72" title="Reference 3">
+(3)
+</a>
+<a href= "#ref-for-dfn-thing-73" title="Reference 4">
+(4)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-74" title="§ 6.8 Media Types">
+§
+6.8
+Media
+Types
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-75" title= "§ 6.10 WoT System Components and their Interconnectivity">
+§
+6.10
+WoT
+System
+Components
+and
+their
+Interconnectivity
+</a>
+<a href= "#ref-for-dfn-thing-76" title="Reference 2">
+(2)
+</a>
+<a href= "#ref-for-dfn-thing-77" title="Reference 3">
+(3)
+</a>
+<a href= "#ref-for-dfn-thing-78" title="Reference 4">
+(4)
+</a>
+<a href= "#ref-for-dfn-thing-79" title="Reference 5">
+(5)
+</a>
+<a href= "#ref-for-dfn-thing-80" title="Reference 6">
+(6)
+</a>
+<a href= "#ref-for-dfn-thing-81" title="Reference 7">
+(7)
+</a>
+<a href= "#ref-for-dfn-thing-82" title="Reference 8">
+(8)
+</a>
+<a href= "#ref-for-dfn-thing-83" title="Reference 9">
+(9)
+</a>
+<a href= "#ref-for-dfn-thing-84" title="Reference 10">
+(10)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-85" title= "§ 6.10.1 Direct Communication">
+§
+6.10.1
+Direct
+Communication
+</a>
+<a href="#ref-for-dfn-thing-86" title="Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-thing-87" title="Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-thing-88" title="Reference 4">
+(4)
+</a>
+<a href="#ref-for-dfn-thing-89" title="Reference 5">
+(5)
+</a>
+<a href="#ref-for-dfn-thing-90" title="Reference 6">
+(6)
+</a>
+<a href="#ref-for-dfn-thing-91" title="Reference 7">
+(7)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-92" title= "§ 6.10.2 Indirect Communication">
+§
+6.10.2
+Indirect
+Communication
+</a>
+<a href="#ref-for-dfn-thing-93" title= "Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-thing-94" title= "Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-thing-95" title= "Reference 4">
+(4)
+</a>
+<a href="#ref-for-dfn-thing-96" title= "Reference 5">
+(5)
+</a>
+<a href="#ref-for-dfn-thing-97" title= "Reference 6">
+(6)
+</a>
+<a href="#ref-for-dfn-thing-98" title= "Reference 7">
+(7)
+</a>
+<a href="#ref-for-dfn-thing-99" title= "Reference 8">
+(8)
+</a>
+<a href="#ref-for-dfn-thing-100" title= "Reference 9">
+(9)
+</a>
+<a href="#ref-for-dfn-thing-101" title= "Reference 10">
+(10)
+</a>
+<a href="#ref-for-dfn-thing-102" title= "Reference 11">
+(11)
+</a>
+<a href="#ref-for-dfn-thing-103" title= "Reference 12">
+(12)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-104" title= "§ 7. WoT Building Blocks">
+§
+7.
+WoT
+Building
+Blocks
+</a>
+<a href= "#ref-for-dfn-thing-105" title="Reference 2">
+(2)
+</a>
+<a href= "#ref-for-dfn-thing-106" title="Reference 3">
+(3)
+</a>
+<a href= "#ref-for-dfn-thing-107" title="Reference 4">
+(4)
+</a>
+<a href= "#ref-for-dfn-thing-108" title="Reference 5">
+(5)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-109" title= "§ 7.1 WoT Thing Description">
+§
+7.1
+WoT
+Thing
+Description
+</a>
+<a href="#ref-for-dfn-thing-110" title="Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-thing-111" title="Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-thing-112" title="Reference 4">
+(4)
+</a>
+<a href="#ref-for-dfn-thing-113" title="Reference 5">
+(5)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-114" title="§ 7.4 WoT Discovery">
+§
+7.4
+WoT
+Discovery
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-115" title= "§ 7.4.2 Exploration Mechanisms">
+§
+7.4.2
+Exploration
+Mechanisms
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-116" title= "§ 7.5 WoT Binding Templates">
+§
+7.5
+WoT
+Binding
+Templates
+</a>
+<a href="#ref-for-dfn-thing-117" title="Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-118" title= "§ 7.6 WoT Scripting API">
+§
+7.6
+WoT
+Scripting
+API
+</a>
+<a href= "#ref-for-dfn-thing-119" title="Reference 2">
+(2)
+</a>
+<a href= "#ref-for-dfn-thing-120" title="Reference 3">
+(3)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-121" title= "§ 8. Abstract Servient Architecture">
+§
+8.
+Abstract
+Servient
+Architecture
+</a>
+<a href="#ref-for-dfn-thing-122" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-123" title= "§ 8.1 Behavior Implementation">
+§
+8.1
+Behavior
+Implementation
+</a>
+<a href="#ref-for-dfn-thing-124" title="Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-thing-125" title="Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-thing-126" title="Reference 4">
+(4)
+</a>
+<a href="#ref-for-dfn-thing-127" title="Reference 5">
+(5)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-128" title="§ 8.2 WoT Runtime">
+§
+8.2
+WoT
+Runtime
+</a>
+<a href="#ref-for-dfn-thing-129" title= "Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-thing-130" title= "Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-thing-131" title= "Reference 4">
+(4)
+</a>
+<a href="#ref-for-dfn-thing-132" title= "Reference 5">
+(5)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-133" title= "§ 8.4 Exposed Thing and Consumed Thing Abstractions">
+§
+8.4
+Exposed
+Thing
+and
+Consumed
+Thing
+Abstractions
+</a>
+<a href= "#ref-for-dfn-thing-134" title="Reference 2">
+(2)
+</a>
+<a href= "#ref-for-dfn-thing-135" title="Reference 3">
+(3)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-136" title= "§ 8.6 Protocol Stack Implementation">
+§
+8.6
+Protocol
+Stack
+Implementation
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-137" title="§ 8.7 System API">
+§
+8.7
+System
+API
+</a>
+<a href="#ref-for-dfn-thing-138" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-139" title= "§ 8.8 Alternative Servient and WoT Implementations">
+§
+8.8
+Alternative
+Servient
+and
+WoT
+Implementations
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-140" title= "§ 8.8.2 Thing Description for Existing Devices">
+§
+8.8.2
+Thing
+Description
+for
+Existing
+Devices
+</a>
+<a href= "#ref-for-dfn-thing-141" title="Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-142" title= "§ 9. Example WoT Deployments">
+§
+9.
+Example
+WoT
+Deployments
+</a>
+<a href="#ref-for-dfn-thing-143" title="Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-thing-144" title="Reference 3">
+(3)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-145" title= "§ 9.1 Thing and Consumer Roles">
+§
+9.1
+Thing
+and
+Consumer
+Roles
+</a>
+<a href="#ref-for-dfn-thing-146" title="Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-thing-147" title="Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-thing-148" title="Reference 4">
+(4)
+</a>
+<a href="#ref-for-dfn-thing-149" title="Reference 5">
+(5)
+</a>
+<a href="#ref-for-dfn-thing-150" title="Reference 6">
+(6)
+</a>
+<a href="#ref-for-dfn-thing-151" title="Reference 7">
+(7)
+</a>
+<a href="#ref-for-dfn-thing-152" title="Reference 8">
+(8)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-153" title= "§ 9.2.1 Consumer and Thing on the Same Network">
+§
+9.2.1
+Consumer
+and
+Thing
+on
+the
+Same
+Network
+</a>
+<a href="#ref-for-dfn-thing-154" title="Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-thing-155" title= "Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-thing-156" title= "Reference 4">
+(4)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-157" title= "§ 9.2.2 Consumer and Thing Connected via Intermediaries">
+§
+9.2.2
+Consumer
+and
+Thing
+Connected
+via
+Intermediaries
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-158" title= "§ 9.2.2.1 Intermediary Acting as a Proxy">
+§
+9.2.2.1
+Intermediary
+Acting
+as
+a
+Proxy
+</a>
+<a href="#ref-for-dfn-thing-159" title= "Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-thing-160" title= "Reference 3">
+(3)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-161" title= "§ 9.2.2.2 Intermediary Acting as a Digital Twin">
+§
+9.2.2.2
+Intermediary
+Acting
+as
+a
+Digital
+Twin
+</a>
+<a href= "#ref-for-dfn-thing-162" title="Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-163" title= "§ 9.2.3 Devices in a Local Network Controlled from a Cloud Service">
+§
+9.2.3
+Devices
+in
+a
+Local
+Network
+Controlled
+from
+a
+Cloud
+Service
+</a>
+<a href="#ref-for-dfn-thing-164" title= "Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-thing-165" title= "Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-thing-166" title= "Reference 4">
+(4)
+</a>
+<a href="#ref-for-dfn-thing-167" title= "Reference 5">
+(5)
+</a>
+<a href="#ref-for-dfn-thing-168" title= "Reference 6">
+(6)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-169" title= "§ 9.2.4 Discovery Using a Thing Description Directory">
+§
+9.2.4
+Discovery
+Using
+a
+Thing
+Description
+Directory
+</a>
+<a href= "#ref-for-dfn-thing-170" title="Reference 2">
+(2)
+</a>
+<a href= "#ref-for-dfn-thing-171" title="Reference 3">
+(3)
+</a>
+<a href= "#ref-for-dfn-thing-172" title="Reference 4">
+(4)
+</a>
+<a href= "#ref-for-dfn-thing-173" title="Reference 5">
+(5)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-174" title= "§ 9.2.5 Service-to-Service Connections Across Multiple Domains">
+§
+9.2.5
+Service-to-Service
+Connections
+Across
+Multiple
+Domains
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-175" title= "§ 9.2.5.1 Connection Through Thing Description Directory Synchronization">
+§
+9.2.5.1
+Connection
+Through
+Thing
+Description
+Directory
+Synchronization
+</a>
+<a href="#ref-for-dfn-thing-176" title= "Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-thing-177" title= "Reference 3">
+(3)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-178" title= "§ 9.2.5.2 Connection Through Proxy Synchronization">
+§
+9.2.5.2
+Connection
+Through
+Proxy
+Synchronization
+</a>
+<a href= "#ref-for-dfn-thing-179" title="Reference 2">
+(2)
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-web-thing" aria-label= "Links in this document to definition: Web Thing">
+<div>
+<a class="self-link" href="#dfn-web-thing" aria-label= "Permalink for definition: Web Thing. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-web-thing-1" title= "§ 6. Abstract WoT System Architecture">
+§
+6.
+Abstract
+WoT
+System
+Architecture
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-web-thing-2" title="§ 6.3 Web Thing">
+§
+6.3
+Web
+Thing
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-wot-thing-description-directory" aria-label= "Links in this document to definition: Thing Description Directory">
+<div>
+<a class="self-link" href= "#dfn-wot-thing-description-directory" aria-label= "Permalink for definition: Thing Description Directory. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-wot-thing-description-directory-1" title= "§ 3. Terminology">
+§
+3.
+Terminology
+</a>
+<a href= "#ref-for-dfn-wot-thing-description-directory-2" title= "Reference 2">
+(2)
+</a>
+<a href= "#ref-for-dfn-wot-thing-description-directory-3" title= "Reference 3">
+(3)
+</a>
+<a href= "#ref-for-dfn-wot-thing-description-directory-4" title= "Reference 4">
+(4)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-thing-description-directory-5" title= "§ 6.1 Fundamental Concepts">
+§
+6.1
+Fundamental
+Concepts
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-thing-description-directory-6" title= "§ 6.4.3 Thing Lifecycle">
+§
+6.4.3
+Thing
+Lifecycle
+</a>
+<a href= "#ref-for-dfn-wot-thing-description-directory-7" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-thing-description-directory-8" title= "§ 7. WoT Building Blocks">
+§
+7.
+WoT
+Building
+Blocks
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-thing-description-directory-9" title= "§ 7.4.2 Exploration Mechanisms">
+§
+7.4.2
+Exploration
+Mechanisms
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-thing-description-directory-10" title="§ 9.1 Thing and Consumer Roles">
+§
+9.1
+Thing
+and
+Consumer
+Roles
+</a>
+<a href="#ref-for-dfn-wot-thing-description-directory-11" title="Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-thing-description-directory-12" title="§ 9.2.4 Discovery Using a Thing Description Directory">
+§
+9.2.4
+Discovery
+Using
+a
+Thing
+Description
+Directory
+</a>
+<a href= "#ref-for-dfn-wot-thing-description-directory-13" title= "Reference 2">
+(2)
+</a>
+<a href= "#ref-for-dfn-wot-thing-description-directory-14" title= "Reference 3">
+(3)
+</a>
+<a href= "#ref-for-dfn-wot-thing-description-directory-15" title= "Reference 4">
+(4)
+</a>
+<a href= "#ref-for-dfn-wot-thing-description-directory-16" title= "Reference 5">
+(5)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-thing-description-directory-17" title="§ 9.2.5.1 Connection Through Thing Description Directory Synchronization">
+§
+9.2.5.1
+Connection
+Through
+Thing
+Description
+Directory
+Synchronization
+</a>
+<a href= "#ref-for-dfn-wot-thing-description-directory-18" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-thing-description-directory-19" title="§ 9.2.5.2 Connection Through Proxy Synchronization">
+§
+9.2.5.2
+Connection
+Through
+Proxy
+Synchronization
+</a>
+<a href= "#ref-for-dfn-wot-thing-description-directory-20" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-thing-description-directory-21" title="§ 11.2 Access to Personally Identifiable Information">
+§
+11.2
+Access
+to
+Personally
+Identifiable
+Information
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-td-fragment" aria-label= "Links in this document to definition: TD Fragment">
+<div>
+<a class="self-link" href="#dfn-td-fragment" aria-label= "Permalink for definition: TD Fragment. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-td-fragment-1" title="§ 3. Terminology">
+§
+3.
+Terminology
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-wot-thing-description-server" aria-label= "Links in this document to definition: Thing Description Server">
+<div>
+<a class="self-link" href="#dfn-wot-thing-description-server" aria-label= "Permalink for definition: Thing Description Server. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-wot-thing-description-server-1" title= "§ 3. Terminology">
+§
+3.
+Terminology
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-wot-thing-model" aria-label= "Links in this document to definition: Thing Model">
+<div>
+<a class="self-link" href="#dfn-wot-thing-model" aria-label= "Permalink for definition: Thing Model. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-wot-thing-model-1" title= "§ 3. Terminology">
+§
+3.
+Terminology
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-thing-model-2" title= "§ 6.1 Fundamental Concepts">
+§
+6.1
+Fundamental
+Concepts
+</a>
+<a href="#ref-for-dfn-wot-thing-model-3" title= "Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-wot-thing-model-17" title="Reference 3">
+(3)
+</a>
+<a href= "#ref-for-dfn-wot-thing-model-18" title="Reference 4">
+(4)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-thing-model-4" title= "§ 6.1.1 Metadata">
+§
+6.1.1
+Metadata
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-thing-model-5" title= "§ 6.1.1.2 Thing Models">
+§
+6.1.1.2
+Thing
+Models
+</a>
+<a href= "#ref-for-dfn-wot-thing-model-6" title="Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-wot-thing-model-7" title= "Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-wot-thing-model-8" title="Reference 4">
+(4)
+</a>
+<a href= "#ref-for-dfn-wot-thing-model-9" title="Reference 5">
+(5)
+</a>
+<a href="#ref-for-dfn-wot-thing-model-10" title= "Reference 6">
+(6)
+</a>
+<a href="#ref-for-dfn-wot-thing-model-11" title="Reference 7">
+(7)
+</a>
+<a href= "#ref-for-dfn-wot-thing-model-12" title="Reference 8">
+(8)
+</a>
+<a href="#ref-for-dfn-wot-thing-model-13" title= "Reference 9">
+(9)
+</a>
+<a href="#ref-for-dfn-wot-thing-model-14" title="Reference 10">
+(10)
+</a>
+<a href= "#ref-for-dfn-wot-thing-model-15" title="Reference 11">
+(11)
+</a>
+<a href="#ref-for-dfn-wot-thing-model-16" title= "Reference 12">
+(12)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-thing-model-19" title= "§ 7.2 Thing Model">
+§
+7.2
+Thing
+Model
+</a>
+<a href= "#ref-for-dfn-wot-thing-model-20" title="Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-wot-thing-model-21" title= "Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-wot-thing-model-22" title="Reference 4">
+(4)
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-transport-protocol" aria-label= "Links in this document to definition: Transport Protocol">
+<div>
+<a class="self-link" href="#dfn-transport-protocol" aria-label="Permalink for definition: Transport Protocol. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-transport-protocol-1" title= "§ 6.7.2 URIs">
+§
+6.7.2
+URIs
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-transport-protocol-2" title= "§ 7.5 WoT Binding Templates">
+§
+7.5
+WoT
+Binding
+Templates
+</a>
+<a href="#ref-for-dfn-transport-protocol-3" title= "Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-transport-protocol-4" title="Reference 3">
+(3)
+</a>
+<a href= "#ref-for-dfn-transport-protocol-5" title="Reference 4">
+(4)
+</a>
+<a href="#ref-for-dfn-transport-protocol-6" title= "Reference 5">
+(5)
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-trusted-environment" aria-label= "Links in this document to definition: Trusted Environment">
+<div>
+<a class="self-link" href="#dfn-trusted-environment" aria-label= "Permalink for definition: Trusted Environment. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-trusted-environment-1" title= "§ 5. Common Deployment Patterns">
+§
+5.
+Common
+Deployment
+Patterns
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-trusted-environment-2" title= "§ 10.4 Trusted Environment Risks">
+§
+10.4
+Trusted
+Environment
+Risks
+</a>
+<a href="#ref-for-dfn-trusted-environment-3" title= "Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-trusted-environment-4" title="Reference 3">
+(3)
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-virtual-thing" aria-label= "Links in this document to definition: Virtual Thing">
+<div>
+<a class="self-link" href="#dfn-virtual-thing" aria-label= "Permalink for definition: Virtual Thing. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-virtual-thing-1" title= "§ 3. Terminology">
+§
+3.
+Terminology
+</a>
+<a href= "#ref-for-dfn-virtual-thing-2" title="Reference 2">
+(2)
+</a>
+<a href= "#ref-for-dfn-virtual-thing-3" title="Reference 3">
+(3)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-virtual-thing-4" title= "§ 5.9 Virtual Things">
+§
+5.9
+Virtual
+Things
+</a>
+<a href= "#ref-for-dfn-virtual-thing-5" title="Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-virtual-thing-6" title= "§ 6.1 Fundamental Concepts">
+§
+6.1
+Fundamental
+Concepts
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-vocabulary" aria-label= "Links in this document to definition: Vocabulary">
+<div>
+<a class="self-link" href="#dfn-vocabulary" aria-label= "Permalink for definition: Vocabulary. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-vocabulary-1" title="§ 3. Terminology">
+§
+3.
+Terminology
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-term" aria-label= "Links in this document to definition: Term">
+<div>
+<a class="self-link" href="#dfn-term" aria-label= "Permalink for definition: Term. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-term-1" title="§ 3. Terminology">
+§
+3.
+Terminology
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-vocabulary-term" aria-label= "Links in this document to definition: Vocabulary Term">
+<div>
+<a class="self-link" href="#dfn-vocabulary-term" aria-label= "Permalink for definition: Vocabulary Term. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-vocabulary-term-1" title= "§ 3. Terminology">
+§
+3.
+Terminology
+</a>
+<a href= "#ref-for-dfn-vocabulary-term-2" title="Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-vocabulary-term-3" title= "Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-vocabulary-term-4" title="Reference 4">
+(4)
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-wot-interface" aria-label= "Links in this document to definition: WoT Interface">
+<div>
+<a class="self-link" href="#dfn-wot-interface" aria-label= "Permalink for definition: WoT Interface. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-wot-interface-1" title= "§ 6.1 Fundamental Concepts">
+§
+6.1
+Fundamental
+Concepts
+</a>
+<a href="#ref-for-dfn-wot-interface-2" title="Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-wot-interface-3" title="Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-wot-interface-4" title= "Reference 4">
+(4)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-interface-5" title= "§ 6.10 WoT System Components and their Interconnectivity">
+§
+6.10
+WoT
+System
+Components
+and
+their
+Interconnectivity
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-interface-6" title= "§ 6.10.1 Direct Communication">
+§
+6.10.1
+Direct
+Communication
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-interface-7" title= "§ 8.1 Behavior Implementation">
+§
+8.1
+Behavior
+Implementation
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-interface-8" title= "§ 8.6 Protocol Stack Implementation">
+§
+8.6
+Protocol
+Stack
+Implementation
+</a>
+<a href="#ref-for-dfn-wot-interface-9" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-interface-10" title= "§ 8.7 System API">
+§
+8.7
+System
+API
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-interface-11" title= "§ 8.8 Alternative Servient and WoT Implementations">
+§
+8.8
+Alternative
+Servient
+and
+WoT
+Implementations
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-wot-profile" aria-label= "Links in this document to definition: WoT Profile">
+<div>
+<a class="self-link" href="#dfn-wot-profile" aria-label= "Permalink for definition: WoT Profile. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-wot-profile-1" title="§ 7.3 Profiles">
+§
+7.3
+Profiles
+</a>
+<a href="#ref-for-dfn-wot-profile-2" title= "Reference 2">
+(2)
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-wot-runtime" aria-label= "Links in this document to definition: WoT Runtime">
+<div>
+<a class="self-link" href="#dfn-wot-runtime" aria-label= "Permalink for definition: WoT Runtime. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-wot-runtime-1" title= "§ 7.6 WoT Scripting API">
+§
+7.6
+WoT
+Scripting
+API
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-runtime-2" title= "§ 8. Abstract Servient Architecture">
+§
+8.
+Abstract
+Servient
+Architecture
+</a>
+<a href="#ref-for-dfn-wot-runtime-3" title= "Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-wot-runtime-4" title= "Reference 3">
+(3)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-runtime-5" title= "§ 8.1 Behavior Implementation">
+§
+8.1
+Behavior
+Implementation
+</a>
+<a href="#ref-for-dfn-wot-runtime-6" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-runtime-7" title= "§ 8.2 WoT Runtime">
+§
+8.2
+WoT
+Runtime
+</a>
+<a href= "#ref-for-dfn-wot-runtime-8" title="Reference 2">
+(2)
+</a>
+<a href= "#ref-for-dfn-wot-runtime-9" title="Reference 3">
+(3)
+</a>
+<a href= "#ref-for-dfn-wot-runtime-10" title="Reference 4">
+(4)
+</a>
+<a href= "#ref-for-dfn-wot-runtime-11" title="Reference 5">
+(5)
+</a>
+<a href= "#ref-for-dfn-wot-runtime-12" title="Reference 6">
+(6)
+</a>
+<a href= "#ref-for-dfn-wot-runtime-13" title="Reference 7">
+(7)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-runtime-14" title= "§ 8.3 WoT Scripting API">
+§
+8.3
+WoT
+Scripting
+API
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-runtime-15" title= "§ 8.4 Exposed Thing and Consumed Thing Abstractions">
+§
+8.4
+Exposed
+Thing
+and
+Consumed
+Thing
+Abstractions
+</a>
+<a href= "#ref-for-dfn-wot-runtime-16" title="Reference 2">
+(2)
+</a>
+<a href= "#ref-for-dfn-wot-runtime-17" title="Reference 3">
+(3)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-runtime-18" title= "§ 8.5 Private Security Data">
+§
+8.5
+Private
+Security
+Data
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-runtime-19" title= "§ 8.7 System API">
+§
+8.7
+System
+API
+</a>
+<a href= "#ref-for-dfn-wot-runtime-20" title="Reference 2">
+(2)
+</a>
+<a href= "#ref-for-dfn-wot-runtime-21" title="Reference 3">
+(3)
+</a>
+<a href= "#ref-for-dfn-wot-runtime-22" title="Reference 4">
+(4)
+</a>
+<a href= "#ref-for-dfn-wot-runtime-23" title="Reference 5">
+(5)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-runtime-24" title= "§ 8.8 Alternative Servient and WoT Implementations">
+§
+8.8
+Alternative
+Servient
+and
+WoT
+Implementations
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-runtime-25" title= "§ 8.8.1 Native WoT API">
+§
+8.8.1
+Native
+WoT
+API
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-runtime-26" title= "§ 9.1 Thing and Consumer Roles">
+§
+9.1
+Thing
+and
+Consumer
+Roles
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-runtime-27" title= "§ 9.2.2 Consumer and Thing Connected via Intermediaries">
+§
+9.2.2
+Consumer
+and
+Thing
+Connected
+via
+Intermediaries
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-runtime-28" title= "§ 10.2 WoT Scripting API Risks">
+§
+10.2
+WoT
+Scripting
+API
+Risks
+</a>
+<a href="#ref-for-dfn-wot-runtime-29" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-runtime-30" title= "§ 10.2.1 Cross-Script Security Risk">
+§
+10.2.1
+Cross-Script
+Security
+Risk
+</a>
+<a href="#ref-for-dfn-wot-runtime-31" title= "Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-wot-runtime-32" title= "Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-wot-runtime-33" title= "Reference 4">
+(4)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-runtime-34" title= "§ 10.2.2 Physical Device Direct Access Risk">
+§
+10.2.2
+Physical
+Device
+Direct
+Access
+Risk
+</a>
+<a href="#ref-for-dfn-wot-runtime-35" title="Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-runtime-36" title= "§ 10.3.1 Provisioning and Update Security Risk">
+§
+10.3.1
+Provisioning
+and
+Update
+Security
+Risk
+</a>
+<a href= "#ref-for-dfn-wot-runtime-37" title="Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-runtime-38" title= "§ 10.3.2 Security Credentials Storage Risk">
+§
+10.3.2
+Security
+Credentials
+Storage
+Risk
+</a>
+<a href="#ref-for-dfn-wot-runtime-39" title="Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-wot-runtime-40" title="Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-wot-runtime-41" title="Reference 4">
+(4)
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-wot-scripting-api" aria-label= "Links in this document to definition: WoT Scripting API">
+<div>
+<a class="self-link" href="#dfn-wot-scripting-api" aria-label= "Permalink for definition: WoT Scripting API. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-wot-scripting-api-1" title= "§ 3. Terminology">
+§
+3.
+Terminology
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-scripting-api-2" title= "§ 7. WoT Building Blocks">
+§
+7.
+WoT
+Building
+Blocks
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-scripting-api-3" title= "§ 7.6 WoT Scripting API">
+§
+7.6
+WoT
+Scripting
+API
+</a>
+<a href= "#ref-for-dfn-wot-scripting-api-4" title="Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-wot-scripting-api-5" title= "Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-wot-scripting-api-6" title="Reference 4">
+(4)
+</a>
+<a href= "#ref-for-dfn-wot-scripting-api-7" title="Reference 5">
+(5)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-scripting-api-8" title= "§ 7.7 WoT Security and Privacy Guidelines">
+§
+7.7
+WoT
+Security
+and
+Privacy
+Guidelines
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-scripting-api-9" title= "§ 8. Abstract Servient Architecture">
+§
+8.
+Abstract
+Servient
+Architecture
+</a>
+<a href="#ref-for-dfn-wot-scripting-api-10" title= "Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-wot-scripting-api-11" title="Reference 3">
+(3)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-scripting-api-12" title= "§ 8.1 Behavior Implementation">
+§
+8.1
+Behavior
+Implementation
+</a>
+<a href="#ref-for-dfn-wot-scripting-api-13" title= "Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-wot-scripting-api-14" title="Reference 3">
+(3)
+</a>
+<a href= "#ref-for-dfn-wot-scripting-api-15" title= "Reference 4">
+(4)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-scripting-api-16" title= "§ 8.2 WoT Runtime">
+§
+8.2
+WoT
+Runtime
+</a>
+<a href= "#ref-for-dfn-wot-scripting-api-17" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-scripting-api-18" title= "§ 8.3 WoT Scripting API">
+§
+8.3
+WoT
+Scripting
+API
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-scripting-api-19" title= "§ 8.4 Exposed Thing and Consumed Thing Abstractions">
+§
+8.4
+Exposed
+Thing
+and
+Consumed
+Thing
+Abstractions
+</a>
+<a href= "#ref-for-dfn-wot-scripting-api-20" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-scripting-api-21" title= "§ 8.8 Alternative Servient and WoT Implementations">
+§
+8.8
+Alternative
+Servient
+and
+WoT
+Implementations
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-scripting-api-22" title= "§ 8.8.1 Native WoT API">
+§
+8.8.1
+Native
+WoT
+API
+</a>
+<a href= "#ref-for-dfn-wot-scripting-api-23" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-scripting-api-24" title= "§ 9.1 Thing and Consumer Roles">
+§
+9.1
+Thing
+and
+Consumer
+Roles
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-scripting-api-25" title= "§ 10.2 WoT Scripting API Risks">
+§
+10.2
+WoT
+Scripting
+API
+Risks
+</a>
+<a href="#ref-for-dfn-wot-scripting-api-26" title= "Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-wot-scripting-api-27" title="Reference 3">
+(3)
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-wot-servient" aria-label= "Links in this document to definition: WoT Servient">
+<div>
+<a class="self-link" href="#dfn-wot-servient" aria-label= "Permalink for definition: WoT Servient. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+Not
+referenced
+in
+this
+document.
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-wot-thing-description" aria-label= "Links in this document to definition: WoT Thing Description">
+<div>
+<a class="self-link" href="#dfn-wot-thing-description" aria-label= "Permalink for definition: WoT Thing Description. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-wot-thing-description-1" title= "§ 3. Terminology">
+§
+3.
+Terminology
+</a>
+<a href= "#ref-for-dfn-wot-thing-description-2" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-thing-description-3" title= "§ 6.1 Fundamental Concepts">
+§
+6.1
+Fundamental
+Concepts
+</a>
+<a href="#ref-for-dfn-wot-thing-description-4" title= "Reference 2">
+(2)
+</a>
+<a href= "#ref-for-dfn-wot-thing-description-6" title="Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-wot-thing-description-7" title= "Reference 4">
+(4)
+</a>
+<a href= "#ref-for-dfn-wot-thing-description-8" title= "Reference 5">
+(5)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-thing-description-5" title= "§ 6.1.1.1 Thing Descriptions">
+§
+6.1.1.1
+Thing
+Descriptions
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-thing-description-9" title= "§ 6.2 Affordances">
+§
+6.2
+Affordances
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-thing-description-10" title= "§ 6.8 Media Types">
+§
+6.8
+Media
+Types
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-thing-description-11" title= "§ 7. WoT Building Blocks">
+§
+7.
+WoT
+Building
+Blocks
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-thing-description-12" title= "§ 7.1 WoT Thing Description">
+§
+7.1
+WoT
+Thing
+Description
+</a>
+<a href="#ref-for-dfn-wot-thing-description-13" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-thing-description-14" title= "§ 7.3.1 Profiling Methodology">
+§
+7.3.1
+Profiling
+Methodology
+</a>
+<a href="#ref-for-dfn-wot-thing-description-15" title= "Reference 2">
+(2)
+</a>
+<a href= "#ref-for-dfn-wot-thing-description-16" title= "Reference 3">
+(3)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-thing-description-17" title= "§ 7.4 WoT Discovery">
+§
+7.4
+WoT
+Discovery
+</a>
+<a href= "#ref-for-dfn-wot-thing-description-18" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-thing-description-19" title= "§ 7.6 WoT Scripting API">
+§
+7.6
+WoT
+Scripting
+API
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-thing-description-20" title= "§ 8.2 WoT Runtime">
+§
+8.2
+WoT
+Runtime
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-thing-description-21" title= "§ 8.3 WoT Scripting API">
+§
+8.3
+WoT
+Scripting
+API
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-thing-description-22" title= "§ 8.7 System API">
+§
+8.7
+System
+API
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-thing-description-23" title= "§ 8.8 Alternative Servient and WoT Implementations">
+§
+8.8
+Alternative
+Servient
+and
+WoT
+Implementations
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-thing-description-24" title= "§ 10.1 WoT Thing Description Risks">
+§
+10.1
+WoT
+Thing
+Description
+Risks
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-wot-thing-description-25" title= "§ 11.1 WoT Thing Description Risks">
+§
+11.1
+WoT
+Thing
+Description
+Risks
+</a>
+</li>
+</ul>
+</div>
+<div class="dfn-panel" hidden="" role="dialog" aria-modal="true" id="dfn-panel-for-dfn-thing-description" aria-label= "Links in this document to definition: Thing Description">
+<div>
+<a class="self-link" href="#dfn-thing-description" aria-label= "Permalink for definition: Thing Description. Activate to close this dialog.">
+Permalink
+</a>
+</div>
+<p>
+<b>
+Referenced
+in:
+</b>
+</p>
+<ul>
+<li>
+<a href="#ref-for-dfn-thing-description-1" title= "§ 1. Introduction">
+§
+1.
+Introduction
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-description-2" title= "§ 3. Terminology">
+§
+3.
+Terminology
+</a>
+<a href= "#ref-for-dfn-thing-description-3" title="Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-thing-description-4" title= "Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-thing-description-5" title="Reference 4">
+(4)
+</a>
+<a href= "#ref-for-dfn-thing-description-6" title="Reference 5">
+(5)
+</a>
+<a href="#ref-for-dfn-thing-description-7" title= "Reference 6">
+(6)
+</a>
+<a href="#ref-for-dfn-thing-description-8" title="Reference 7">
+(7)
+</a>
+<a href= "#ref-for-dfn-thing-description-9" title="Reference 8">
+(8)
+</a>
+<a href="#ref-for-dfn-thing-description-10" title= "Reference 9">
+(9)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-description-11" title= "§ 6.1 Fundamental Concepts">
+§
+6.1
+Fundamental
+Concepts
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-description-12" title= "§ 6.1.1 Metadata">
+§
+6.1.1
+Metadata
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-description-13" title= "§ 6.1.1.2 Thing Models">
+§
+6.1.1.2
+Thing
+Models
+</a>
+<a href= "#ref-for-dfn-thing-description-14" title="Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-thing-description-15" title= "Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-thing-description-16" title="Reference 4">
+(4)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-description-17" title= "§ 6.4.2 System Lifecycle with Registration">
+§
+6.4.2
+System
+Lifecycle
+with
+Registration
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-description-18" title= "§ 6.4.3 Thing Lifecycle">
+§
+6.4.3
+Thing
+Lifecycle
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-description-19" title= "§ 6.10 WoT System Components and their Interconnectivity">
+§
+6.10
+WoT
+System
+Components
+and
+their
+Interconnectivity
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-description-20" title= "§ 6.10.1 Direct Communication">
+§
+6.10.1
+Direct
+Communication
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-description-21" title= "§ 6.10.2 Indirect Communication">
+§
+6.10.2
+Indirect
+Communication
+</a>
+<a href="#ref-for-dfn-thing-description-22" title="Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-description-23" title= "§ 7. WoT Building Blocks">
+§
+7.
+WoT
+Building
+Blocks
+</a>
+<a href= "#ref-for-dfn-thing-description-24" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-description-25" title= "§ 7.1 WoT Thing Description">
+§
+7.1
+WoT
+Thing
+Description
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-description-26" title= "§ 7.2 Thing Model">
+§
+7.2
+Thing
+Model
+</a>
+<a href= "#ref-for-dfn-thing-description-27" title="Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-thing-description-28" title= "Reference 3">
+(3)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-description-29" title= "§ 7.5 WoT Binding Templates">
+§
+7.5
+WoT
+Binding
+Templates
+</a>
+<a href="#ref-for-dfn-thing-description-30" title= "Reference 2">
+(2)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-description-31" title= "§ 7.6 WoT Scripting API">
+§
+7.6
+WoT
+Scripting
+API
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-description-32" title= "§ 8.6 Protocol Stack Implementation">
+§
+8.6
+Protocol
+Stack
+Implementation
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-description-33" title= "§ 8.8.2 Thing Description for Existing Devices">
+§
+8.8.2
+Thing
+Description
+for
+Existing
+Devices
+</a>
+<a href= "#ref-for-dfn-thing-description-34" title="Reference 2">
+(2)
+</a>
+<a href="#ref-for-dfn-thing-description-35" title= "Reference 3">
+(3)
+</a>
+<a href="#ref-for-dfn-thing-description-36" title="Reference 4">
+(4)
+</a>
+</li>
+<li>
+<a href="#ref-for-dfn-thing-description-37" title= "§ 9.1 Thing and Consumer Roles">
+§
+9.1
+Thing
+and
+Consumer
+Roles
+</a>
+</li>
+</ul>
+</div>
+<script id="respec-dfn-panel">
+<![CDATA[ (() =>
+{
+//
+@ts-check
+if
+(document.respec)
+{
+document.respec.ready.then(setupPanel);
+}
+else
+{
+setupPanel();
+}
+function
+setupPanel()
+{
+const
+listener
+=
+panelListener();
+document.body.addEventListener("keydown",
+listener);
+document.body.addEventListener("click",
+listener);
+}
+function
+panelListener()
+{
+/**
+@type
+{HTMLElement}
+*/
+let
+panel
+=
+null;
+return
+event
+=>
+{
+const
+{
+target,
+type
+}
+=
+event;
+if
+(!(target
+instanceof
+HTMLElement))
+return;
+//
+For
+keys,
+we
+only
+care
+about
+Enter
+key
+to
+activate
+the
+panel
+//
+otherwise
+it's
+activated
+via
+a
+click.
+if
+(type
+===
+"keydown"
+&&
+event.key
+!==
+"Enter")
+return;
+const
+action
+=
+deriveAction(event);
+switch
+(action)
+{
+case
+"show":
+{
+hidePanel(panel);
+/**
+@type
+{HTMLElement}
+*/
+const
+dfn
+=
+target.closest("dfn,
+.index-term");
+panel
+=
+document.getElementById(`dfn-panel-for-${dfn.id}`);
+const
+coords
+=
+deriveCoordinates(event);
+displayPanel(dfn,
+panel,
+coords);
+break;
+}
+case
+"dock":
+{
+panel.style.left
+=
+null;
+panel.style.top
+=
+null;
+panel.classList.add("docked");
+break;
+}
+case
+"hide":
+{
+hidePanel(panel);
+panel
+=
+null;
+break;
+}
+}
+};
+}
+/**
+*
+@param
+{MouseEvent|KeyboardEvent}
+event
+*/
+function
+deriveCoordinates(event)
+{
+const
+target
+=
+/**
+@type
+HTMLElement
+*/
+(event.target);
+//
+We
+prevent
+synthetic
+AT
+clicks
+from
+putting
+//
+the
+dialog
+in
+a
+weird
+place.
+The
+AT
+events
+sometimes
+//
+lack
+coordinates,
+so
+they
+have
+clientX/Y
+=
+0
+const
+rect
+=
+target.getBoundingClientRect();
+if
+(
+event
+instanceof
+MouseEvent
+&&
+event.clientX
+>
+=
+rect.left
+&&
+event.clientY
+>
+=
+rect.top
+)
+{
+//
+The
+event
+probably
+happened
+inside
+the
+bounding
+rect...
+return
+{
+x:
+event.clientX,
+y:
+event.clientY
+};
+}
+//
+Offset
+to
+the
+middle
+of
+the
+element
+const
+x
+=
+rect.x
++
+rect.width
+/
+2;
+//
+Placed
+at
+the
+bottom
+of
+the
+element
+const
+y
+=
+rect.y
++
+rect.height;
+return
+{
+x,
+y
+};
+}
+/**
+*
+@param
+{Event}
+event
+*/
+function
+deriveAction(event)
+{
+const
+target
+=
+/**
+@type
+{HTMLElement}
+*/
+(event.target);
+const
+hitALink
+=
+!!target.closest("a");
+if
+(target.closest("dfn:not([data-cite]),
+.index-term"))
+{
+return
+hitALink
+?
+"none"
+:
+"show";
+}
+if
+(target.closest(".dfn-panel"))
+{
+if
+(hitALink)
+{
+return
+target.classList.contains("self-link")
+?
+"hide"
+:
+"dock";
+}
+const
+panel
+=
+target.closest(".dfn-panel");
+return
+panel.classList.contains("docked")
+?
+"hide"
+:
+"none";
+}
+if
+(document.querySelector(".dfn-panel:not([hidden])"))
+{
+return
+"hide";
+}
+return
+"none";
+}
+/**
+*
+@param
+{HTMLElement}
+dfn
+*
+@param
+{HTMLElement}
+panel
+*
+@param
+{{
+x:
+number,
+y:
+number
+}}
+clickPosition
+*/
+function
+displayPanel(dfn,
+panel,
+{
+x,
+y
+})
+{
+panel.hidden
+=
+false;
+//
+distance
+(px)
+between
+edge
+of
+panel
+and
+the
+pointing
+triangle
+(caret)
+const
+MARGIN
+=
+20;
+const
+dfnRects
+=
+dfn.getClientRects();
+//
+Find
+the
+`top`
+offset
+when
+the
+`dfn`
+can
+be
+spread
+across
+multiple
+lines
+let
+closestTop
+=
+0;
+let
+minDiff
+=
+Infinity;
+for
+(const
+rect
+of
+dfnRects)
+{
+const
+{
+top,
+bottom
+}
+=
+rect;
+const
+diffFromClickY
+=
+Math.abs((top
++
+bottom)
+/
+2
+-
+y);
+if
+(diffFromClickY
+< minDiff) { minDiff = diffFromClickY; closestTop = top; } } const top = window.scrollY + closestTop + dfnRects[0].height; const left = x - MARGIN; panel.style.left = `${left}px`; panel.style.top = `${top}px`; // Find if the panel is flowing out of the window const panelRect = panel.getBoundingClientRect(); const SCREEN_WIDTH = Math.min(window.innerWidth, window.screen.width); if (panelRect.right >
+SCREEN_WIDTH)
+{
+const
+newLeft
+=
+Math.max(MARGIN,
+x
++
+MARGIN
+-
+panelRect.width);
+const
+newCaretOffset
+=
+left
+-
+newLeft;
+panel.style.left
+=
+`${newLeft}px`;
+/**
+@type
+{HTMLElement}
+*/
+const
+caret
+=
+panel.querySelector(".caret");
+caret.style.left
+=
+`${newCaretOffset}px`;
+}
+//
+As
+it's
+a
+dialog,
+we
+trap
+focus.
+//
+TODO:
+when
+<dialog>
+becomes
+a
+implemented,
+we
+should
+really
+//
+use
+that.
+trapFocus(panel,
+dfn);
+}
+/**
+*
+@param
+{HTMLElement}
+panel
+*
+@param
+{HTMLElement}
+dfn
+*
+@returns
+*/
+function
+trapFocus(panel,
+dfn)
+{
+/**
+@type
+NodeListOf
+<HTMLAnchorElement>
+elements
+*/
+const
+anchors
+=
+panel.querySelectorAll("a[href]");
+//
+No
+need
+to
+trap
+focus
+if
+(!anchors.length)
+return;
+//
+Move
+focus
+to
+first
+anchor
+element
+const
+first
+=
+anchors.item(0);
+first.focus();
+const
+trapListener
+=
+createTrapListener(anchors,
+panel,
+dfn);
+panel.addEventListener("keydown",
+trapListener);
+//
+Hiding
+the
+panel
+releases
+the
+trap
+const
+mo
+=
+new
+MutationObserver(records
+=>
+{
+const
+[record]
+=
+records;
+const
+target
+=
+/**
+@type
+HTMLElement
+*/
+(record.target);
+if
+(target.hidden)
+{
+panel.removeEventListener("keydown",
+trapListener);
+mo.disconnect();
+}
+});
+mo.observe(panel,
+{
+attributes:
+true,
+attributeFilter:
+["hidden"]
+});
+}
+/**
+*
+*
+@param
+{NodeListOf
+<HTMLAnchorElement>
+}
+anchors
+*
+@param
+{HTMLElement}
+panel
+*
+@param
+{HTMLElement}
+dfn
+*
+@returns
+*/
+function
+createTrapListener(anchors,
+panel,
+dfn)
+{
+const
+lastIndex
+=
+anchors.length
+-
+1;
+let
+currentIndex
+=
+0;
+return
+event
+=>
+{
+switch
+(event.key)
+{
+//
+Hitting
+"Tab"
+traps
+us
+in
+a
+nice
+loop
+around
+elements.
+case
+"Tab":
+{
+event.preventDefault();
+currentIndex
++=
+event.shiftKey
+?
+-1
+:
++1;
+if
+(currentIndex
+< 0) { currentIndex = lastIndex; } else if (currentIndex >
+lastIndex)
+{
+currentIndex
+=
+0;
+}
+anchors.item(currentIndex).focus();
+break;
+}
+//
+Hitting
+"Enter"
+on
+an
+anchor
+releases
+the
+trap.
+case
+"Enter":
+hidePanel(panel);
+break;
+//
+Hitting
+"Escape"
+returns
+focus
+to
+dfn.
+case
+"Escape":
+hidePanel(panel);
+dfn.focus();
+return;
+}
+};
+}
+/**
+@param
+{HTMLElement}
+panel
+*/
+function
+hidePanel(panel)
+{
+if
+(!panel)
+return;
+panel.hidden
+=
+true;
+panel.classList.remove("docked");
+}
+})()
+]]>
+</script>
+<script src="https://www.w3.org/scripts/TR/2021/fixup.js">
+</script>
+</body>
+</html>
diff --git a/publication/ver11/5-rec/index.html b/publication/ver11/5-rec/index.html
index daf06176..7e4e6de0 100644
--- a/publication/ver11/5-rec/index.html
+++ b/publication/ver11/5-rec/index.html
@@ -18,7 +18,7 @@
       noIDLIn:        true,
       group: "wg/wot",
       specStatus: "REC",
-      publishDate: "2023-11-30",
+      publishDate: "2023-12-05",
       shortName: "wot-architecture11",
       copyrightStart: 2017,
       wgPublicList: "public-wot-wg",
diff --git a/publication/ver11/5-rec/static.html b/publication/ver11/5-rec/static.html
index dc6e27ce..c32f514f 100644
--- a/publication/ver11/5-rec/static.html
+++ b/publication/ver11/5-rec/static.html
@@ -152,7 +152,7 @@
   "name": "Web of Things (WoT) Architecture 1.1",
   "inLanguage": "en-US",
   "license": "https://www.w3.org/copyright/software-license-2023/",
-  "datePublished": "2023-11-30",
+  "datePublished": "2023-12-05",
   "copyrightHolder": {
     "name": "World Wide Web Consortium",
     "url": "https://www.w3.org/"
@@ -1128,7 +1128,7 @@
   "noIDLIn": true,
   "group": "wg/wot",
   "specStatus": "REC",
-  "publishDate": "2023-11-30",
+  "publishDate": "2023-12-05",
   "shortName": "wot-architecture11",
   "copyrightStart": 2017,
   "wgPublicList": "public-wot-wg",
@@ -1453,8 +1453,8 @@
       "id": "wot-security"
     }
   },
-  "publishISODate": "2023-11-30T00:00:00.000Z",
-  "generatedSubtitle": "W3C Recommendation 30 November 2023"
+  "publishISODate": "2023-12-05T00:00:00.000Z",
+  "generatedSubtitle": "W3C Recommendation 05 December 2023"
 }</script>
 <link rel="stylesheet" href="https://www.w3.org/StyleSheets/TR/2021/W3C-REC"></head>
 
@@ -1462,12 +1462,12 @@
     <p class="logos"><a class="logo" href="https://www.w3.org/"><img crossorigin="" alt="W3C" height="48" src="https://www.w3.org/StyleSheets/TR/2021/logos/W3C" width="72">
   </a></p>
     <h1 id="title" class="title">Web of Things (WoT) Architecture 1.1</h1> 
-    <p id="w3c-state"><a href="https://www.w3.org/standards/types#REC">W3C Recommendation</a> <time class="dt-published" datetime="2023-11-30">30 November 2023</time></p>
+    <p id="w3c-state"><a href="https://www.w3.org/standards/types#REC">W3C Recommendation</a> <time class="dt-published" datetime="2023-12-05">05 December 2023</time></p>
     <details open="">
       <summary>More details about this document</summary>
       <dl>
         <dt>This version:</dt><dd>
-                <a class="u-url" href="https://www.w3.org/TR/2023/REC-wot-architecture11-20231130/">https://www.w3.org/TR/2023/REC-wot-architecture11-20231130/</a>
+                <a class="u-url" href="https://www.w3.org/TR/2023/REC-wot-architecture11-20231205/">https://www.w3.org/TR/2023/REC-wot-architecture11-20231205/</a>
               </dd>
         <dt>Latest published version:</dt><dd>
                 <a href="https://www.w3.org/TR/wot-architecture11/">https://www.w3.org/TR/wot-architecture11/</a>