Profiling Mechanism
+Profiling Mechanism
- This section describes a generic mechanism to define a - profile of the WoT Thing Description in a unambiguous way. + In order to conform with a profile, a + Web Thing + MUST conform with all the normative statements in the profile's specification.
- The W3C WoT Thing Description specification defines a
- formal language, i.e. a set of vocabulary terms (keywords),
- a set of classes that are built from these keywords, and a
- set of additional rules, that define constraints on
- permitted values and keyword presence (mandatory / optional)
- dependent on the context where the keyword is used. In
- addition the WoT Thing Description specification defines relationships and
- corresponding cardinalities between these classes.
+ In order to denote that a given
+ Web Thing
+ conforms to one or more profiles, its Thing Description MUST include a
+
+ profile member [[wot-thing-description]]. The value of
+ the profile member MUST be set to either a valid URI
+ [[RFC3986]] identifying a single profile, or an array of valid URIs
+ identifying multiple profiles.
- The WoT Thing Description specification already has some constraints, - but there is a wide variety of variations that are left to - the interpretation or the discretion of an implementer. The - rationale for the Core Profile is not to forbid - complex things, rather to enable statements like: -
- --
-
- If you constrain your TD to the Core - Profile, all other devices that conform the Core - Profile can interoperate with it out of the box. - -
- If you have additional needs your - device is free to implement other profiles or - add-ons at your own choice, but other devices that - only implement the Core Profile will most - likely not be able to use these additions.” - -
Methodology
- -- A profile is a set of constraints and rules, which - provide additional semantic guarantees that are applied - to the WoT Thing Description specification. These constraints define a - subset of valid WoT Thing Descriptions by defining - additional rules on various aspects of the WoT Thing - Description specification. -
- -| Constraints on | -Rationale | -Example | -
|---|---|---|
| vocabulary of Thing Description classes | -guaranteed set of metadata fields | -Make specific vocabulary terms mandatory, - remove others | -
| class relationships | -unambiguous structure | -limited cardinality, e.g. only one form per - operation per interaction affordance. | -
| values of vocabulary terms | -simplified processing | -Limit the length of characters per string. - Always use arrays, where the spec permits a - string or an array of strings. | -
| data schemas | -simplified processing | -No arbitrary nested objects or arrays of - arrays | -
| security | -reduced implementation effort | -Only a restricted set of security - mechanisms | -
| protocol binding | -guaranteed protocol semantics | -limited protocol(s) and protocol features, - Example: predefined mapping of http verbs (GET/PUT) to - operation verbs, similar constraints for other protocols. | -
These constraints and rules fall into two categories:
--
-
- constraints for the data model. -
- constraints for the protocol binding. -
These two categories are orthogonal to each other, - i.e. a data model that conforms to a profile can be - mapped to different protocols. - - The protocol binding for - each protocol may contain additional (protocol-specific) - constraints. - -
- -- - 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 the core profile.
-- This specification does not put any requirements on the - scope and contents of other profiles. -
- -
- - In the present document, we define a Core Profile - by defining a Core Data Model and a set of Protocol Binding Rules - for selected protocols. - -
-
+ {
+ "@context": "https://www.w3.org/2019/wot/td/v1",
+ "id": "urn:dev:ops:32473-WoTLamp-1234",
+ "profile": "https://www.w3.org/2021/wot/profile/core",
+ "title": "My Lamp",
+ "description": "A web connected lamp",
+ ...
+ }
+
+
+ {
+ "@context": "https://www.w3.org/2019/wot/td/v1",
+ "id": "urn:dev:ops:32473-WoTLamp-1234",
+ "profile": [
+ "https://www.w3.org/2021/wot/profile/core",
+ "https://www.w3.org/2021/wot/profile/constrained"
+ ],
+ "title": "My Lamp",
+ "description": "A web connected lamp",
+ ...
+ }
+