Ogre is a Clojure Gremlin Language Variant of the Gremlin graph traversal language from Apache Tinkerpop. Like Gremlin, it can be used to query any graphs that are TinkerPop-enabled.
- Provide an API that enhances the expressivity of Gremlin when working in Clojure.
- Expose the features of TinkerPop as it makes sense in Clojure.
- Don't introduce any significant amount of performance overhead.
Questions related to Ogre can be asked on the clojure-titanium mailing list.
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Despite being first released in 2014, Orge is a relatively young project that regained active development in 2016. Most of Ogre's features are driven by changes to Apache TinkerPop (specifically the Traversal API) which has largely stabilized itself in over the course of the 3.2.x line of code. As a result, Ogre tends to be fairly stable with its implementation of that API. Ogre also implements the TinkerPop Process Test Suite, which helps validate that Ogre is compliant with Gremlin.
Ogre currently targets TinkerPop 3.4.x.
Orge artifacts are released to Clojars. Maven users should add the following
repository definition to your pom.xml:
<repository>
<id>clojars.org</id>
<url>http://clojars.org/repo</url>
</repository>With Leiningen:
[clojurewerkz/ogre "3.4.11.0"]
With Maven:
<dependency>
<groupId>clojurewerkz</groupId>
<artifactId>ogre</artifactId>
<version>3.4.11.0</version>
</dependency>
You'll need to choose a TinkerPop-enabled graph database and add that to your project's dependencies. Here we use the
in-memory graph database implementation provided by org.apache.tinkerpop/tinkergraph-gremlin, e.g.:
With Leiningen:
[org.apache.tinkerpop/tinkergraph-gremlin "3.4.11"]
With Maven:
<dependency>
<groupId>org.apache.tinkerpop</groupId>
<artifactId>tinkergraph-gremlin</artifactId>
<version>3.4.11</version>
</dependency>
REPL examples:
user=> (load "clojurewerkz/ogre/core")
nil
user=> (in-ns 'clojurewerkz.ogre.core)
#object[clojure.lang.Namespace 0x2bcfe59c "clojurewerkz.ogre.core"]
clojurewerkz.ogre.core=> (def graph (open-graph {(Graph/GRAPH) (.getName org.apache.tinkerpop.gremlin.tinkergraph.structure.TinkerGraph)}))
#'clojurewerkz.ogre.core/graph
clojurewerkz.ogre.core=> (def g (traversal graph))
#'clojurewerkz.ogre.core/g
clojurewerkz.ogre.core=> (org.apache.tinkerpop.gremlin.tinkergraph.structure.TinkerFactory/generateModern graph)
nil
clojurewerkz.ogre.core=> (traverse g V (match
#_=> (__ (as :a) (out :created) (as :b))
#_=> (__ (as :b) (has :name "lop"))
#_=> (__ (as :b) (in :created) (as :c))
#_=> (__ (as :c) (has :age 29)))
#_=> (select :a :c) (by :name)
#_=> (into-seq!))
({"a" "marko", "c" "marko"} {"a" "josh", "c" "marko"} {"a" "peter", "c" "marko"})
As an alternative to embedded graph databases like TinkerGraph, you might also choose to utilize a remote graph (e.g.
one hosted in Gremlin Server or
a Remote Gremlin Provider). In such case, you
would first need org.apache.tinkerpop/gremlin-driver to connect to the remote graph:
With Leiningen:
[org.apache.tinkerpop/gremlin-driver "3.4.11"]
With Maven:
<dependency>
<groupId>org.apache.tinkerpop</groupId>
<artifactId>gremlin-driver</artifactId>
<version>3.4.11</version>
</dependency>
From the driver, you create a DriverRemoteConnection and pass that to the traversal function (rather than the
Graph instance as demonstrated in the last example):
clojurewerkz.ogre.core=> (def conn (org.apache.tinkerpop.gremlin.driver.remote.DriverRemoteConnection/using "localhost" 8182 "g"))
#'clojurewerkz.ogre.core/conn
clojurewerkz.ogre.core=> (def g (traversal conn))
#'clojurewerkz.ogre.core/g
clojurewerkz.ogre.core=> (traverse g V (has :name "josh") (values :age) (into-seq!))
(32)
In short, to connect to a remote graph simply use Java interop to construct a DriverRemoteConnection instance in the
ways specified by the TinkerPop Reference Documentation
and then give that object to the traversal function to create g.
Ogre has more complete documentation here.
Orge requires Clojure 1.8+. The most recent stable release is always recommended.
Orge uses Leiningen 2. Once installed and run tests using:
lein test
Copyright (C) 2014-2017 Zack Maril, and the ClojureWerkz team. Copyright (C) 2017-2021 Stephen Mallette, Zack Maril, and the ClojureWerkz team.
Licensed under the Eclipse Public License (the same as Clojure).
Joe Lee illustrated the "Gremlin Ogre" image based on the original Clojurewerkz Ogre logo and Apache TinkerPop's Gremlin character developed Ketrina Yim.