gremlin-node

Implementation of Gremlin for node.js. Gremlin-node is a javascript wrapper around the Gremlin API. The node-java module provides the bridge between node and Java.

var Gremlin = require('gremlin');
var gremlin = new Gremlin({
  classpath: [ ... ],
  options: [ ... ]
});

var TinkerGraphFactory = gremlin.java.import('com.tinkerpop.blueprints.impls.tg.TinkerGraphFactory');
var graph = TinkerGraphFactory.createTinkerGraphSync();
var g = gremlin.wrap(graph);

g.V('name', 'marko').next(function (err, v) {
  v.getProperty('name', function (err, value) {
    console.log(value);
  });
});

Dependencies

node-java

Bridge API to connect with existing Java APIs. Please read the node-java installation notes, as it outlines how to install the node-java module on specific platforms and its dependencies.

maven

Maven enables the installation of the base jar files.

Installation

$ npm install gremlin

Gremlin-node includes the required .jar files for Gremlin and the TinkerPop stack. It doesn't include any backend specific jars for databases such as Titan or OrientDB.

Configuration

The Gremlin constructor takes in an object with two properties; classpath which allows you to load in jar files from your own project and options which allows you to supply parameters to the Java runtime.

var Gremlin = require('gremlin');
var gremlin = new Gremlin({
  classpath: [
    path.join(__dirname, '..', 'target', '**', '*.jar')
  ],
  options: [
    '-XX:+UseThreadPriorities',
    '-XX:ThreadPriorityPolicy=42',
    '-XX:+UseParNewGC',
    '-XX:+UseConcMarkSweepGC',
    '-XX:+CMSParallelRemarkEnabled',
    '-XX:SurvivorRatio=8',
    '-XX:MaxTenuringThreshold=1',
    '-XX:CMSInitiatingOccupancyFraction=75',
    '-XX:+UseCMSInitiatingOccupancyOnly',
    '-XX:+UseTLAB',
    '-XX:+UseCondCardMark'
  ]
});

Connecting to a Graph

As mentioned above, gremlin-node only includes jars for the reference Blueprints implementation, TinkerGraph.

To use another database implementing the Blueprints property graph interfaces (e.g. Titan or OrientDB), the Gremlin constructor must point to a location with the databases compiled jars. A quickstart project for using Titan with gremlin-node is up at titan-node.

Once the dependent jars are properly loaded into the Java runtime, a graph instance must be created and passed to gremlin.wrap.

TinkerGraph

var TinkerGraphFactory = gremlin.java.import('com.tinkerpop.blueprints.impls.tg.TinkerGraphFactory');
var graph = TinkerGraphFactory.createTinkerGraphSync();
var g = gremlin.wrap(graph);

Titan

var TitanFactory = gremlin.java.import('com.thinkaurelius.titan.core.TitanFactory');
var graph = TitanFactory.openSync('local:/path/to/config');
var g = gremlin.wrap(graph);

OrientGraph

var OrientGraph = g.java.import('com.tinkerpop.blueprints.impls.orient.OrientGraph');
var graph = new OrientGraph('local:/path/to/database/files', 'admin', 'admin');
var g = gremlin.wrap(graph);

Working with the Database

Once you have connected to the database, you are able to call all implementation specific database methods. For example here's how you would add two Vertices and an Edge and associate them in an OrientDB graph.

var luca = graph.addVertexSync(null);
luca.setPropertySync( 'name', 'Luca' );

var marko = graph.addVertexSync(null);
marko.setPropertySync( 'name', 'Marko' );

var lucaKnowsMarko = graph.addEdgeSync(null, luca, marko, 'knows');

graph.commitSync();

Examples

NOTE: These examples are currently out of date. The best reference for now is in the unit tests.

A good resource to understand the Gremlin API is GremlinDocs. Below are examples of gremlin and it's equivalent gremlin-node syntax.

Example 1: Basic Transforms

gremlin>  g.V('name', 'marko').out

node>     g.V('name', 'marko').out();

node>     g.V({name: 'marko'}).out();

gremlin>  g.v(1, 4).out('knows', 'created').in

node>     g.v(1, 4).out('knows', 'created').in();

node>     g.v([1, 4]).out(['knows', 'created']).in(); 

Example 2: [i]

gremlin>  g.V[0].name

node>     g.V().index(0).property('name');

Example 3: [i..j]

gremlin>  g.V[0..<2].name

node>     g.V().range(0,1).property('name');

Example 4: has

gremlin>    g.E.has('weight', T.gt, 0.5f).outV.transform{[it.id,it.age]}

node>       g.E().has('weight', T.gt, '0.5f').outV().transform('{[it.id,it.age]}');

Example 5: and & or

gremlin>  g.V.and(_().both('knows'), _().both('created'))

node>     g.V().and(g._().both('knows'), g._().both('created'));

gremlin>  g.v(1).outE.or(_().has('id', T.eq, '9'), _().has('weight', T.lt, 0.6f))

node>     g.v(1).outE().or(g._().has('id', T.eq, 9), g._().has('weight', T.lt, '0.6f')); 

Example 6: groupBy

gremlin>    g.V.out.groupBy{it.name}{it.in}{it.unique().findAll{i -> i.age > 30}.name}.cap

node>       g.V().out().groupBy('{it.name}{it.in}{it.unique().findAll{i -> i.age > 30}.name}').cap();

Example 7: retain

gremlin>  g.V.retain([g.v(1), g.v(2), g.v(3)])

node>     g.V().retain([g.v(1), g.v(2), g.v(3)]);

Example 8: groupBy with map

gremlin>    m = [:]

gremlin>    g.V.groupBy(m){it}{it.out}.iterate();null;

node>       var map = new g.HashMap();

node>       g.V().groupBy(map, '{it}{it.out}').iterate();

Example 9: aggregate

gremlin>    x = []

gremlin>    g.v(1).out.aggregate(x).out.retain(x)

node>       var x = new g.ArrayList();

node>       g.v(1).out().aggregate(x).out().retain(x);

Example 10: accessing returned values

node>       g.v(1).out().iterator().toListSync();

node>       g.v(1).out().toList();

node>       g.v(1).out().toJSON();

Example 11: Adding Vertices and Edge

node>       var luca = graphDB.addVertexSync(null);
node>       luca.setPropertySync( 'name', 'Luca' );

node>       var marko = graphDB.addVertexSync(null);
node>       marko.setPropertySync( 'name', 'Marko' );

node>       var lucaKnowsMarko = graphDB.addEdgeSync(null, luca, marko, 'knows');

node>       graphDB.commitSync();

Example 12: Updating Vertices

node>       var marko = g.V('name', 'Marko').iterator().nextSync();
node>       marko.setPropertySync('name', 'Frank');

node>       var luca = g.v('8:27').iterator().nextSync();
node>       luca.setPropertySync('name', 'John');

node>       graphDB.commitSync();

Example 13: Removing a Vertex

node>       var marko = g.v(1).iterator().nextSync();
node>		marko.removeSync();
node>		graphDB.commitSync();

Example 14: Removing Vertices

node>       var vertices = g.V().iterator();
node>		var element;
node>		while(vertices.hasNextSync()){
				element = vertices.nextSync();
				element.removeSync();
			};
node>		graphDB.commitSync();

Example 15: linkBoth/linkIn/linkOut

gremlin>  marko = g.v(1)
gremlin>  g.V.except([marko]).linkBoth('connected', marko)

// This type of operation, retrieving the underlying vertex using nextSync()
// cannot be done on a JS variable
node>     g.V().except(g.v(1)).linkBoth('connected', g.v(1).iterator().nextSync());

Authors

Frank Panetta - Follow @entrendipity

Anthony Pesch - inolen

Contributors

Jared Camins-Esakov

##License ###The MIT License (MIT)

Copyright (c) 2013 entrendipity pty ltd Parts copyright (c) 2013 C & P Bibliography Services, LLC

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.