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Connecting from Java

While it is possible to embed JanusGraph as a library inside a Java application and then directly connect to the backend, this section assumes that the application connects to JanusGraph Server. For information on how to embed JanusGraph, see the JanusGraph Examples projects.

This section only covers how applications can connect to JanusGraph Server using the GraphBinary serialization. Refer to Gremlin Query Language for an introduction to Gremlin and pointers to further resources.

Getting Started with JanusGraph and Gremlin-Java

To get started with JanusGraph in Java:

  1. Create an application with Maven:

    mvn archetype:generate -DgroupId=com.mycompany.project
    -DartifactId=gremlin-example
    -DarchetypeArtifactId=maven-archetype-quickstart
    -DinteractiveMode=false

  2. Add dependencies on janusgraph-driver and gremlin-driver to the dependency manager:

    <dependency>
    <groupId>org.janusgraph</groupId>
    <artifactId>janusgraph-driver</artifactId>
    <version>1.1.0</version>
</dependency>
<dependency>
    <groupId>org.apache.tinkerpop</groupId>
    <artifactId>gremlin-driver</artifactId>
    <version>3.7.3</version>
</dependency>

    implementation "org.janusgraph:janusgraph-driver:1.1.0"
implementation "org.apache.tinkerpop:gremlin-driver:3.7.3"

  3. Add two configuration files, conf/remote-graph.properties and conf/remote-objects.yaml:

    gremlin.remote.remoteConnectionClass=org.apache.tinkerpop.gremlin.driver.remote.DriverRemoteConnection
gremlin.remote.driver.clusterFile=conf/remote-objects.yaml
gremlin.remote.driver.sourceName=g

    hosts: [localhost]
port: 8182
serializer: { 
    className: org.apache.tinkerpop.gremlin.util.ser.GraphBinaryMessageSerializerV1,
    config: { ioRegistries: [org.janusgraph.graphdb.tinkerpop.JanusGraphIoRegistry] }}

  4. Create a GraphTraversalSource which is the basis for all Gremlin traversals:

    import static org.apache.tinkerpop.gremlin.process.traversal.AnonymousTraversalSource.traversal;

GraphTraversalSource g = traversal().withRemote("conf/remote-graph.properties");
// Reuse 'g' across the application
// and close it on shut-down to close open connections with g.close()

  5. Execute a simple traversal:

    Object herculesAge = g.V().has("name", "hercules").values("age").next();
System.out.println("Hercules is " + herculesAge + " years old.");

    next() is a terminal step that submits the traversal to the Gremlin Server and returns a single result.

JanusGraph Specific Types and Predicates

JanusGraph specific types and predicates can be used directly from a Java application through the dependency janusgraph-driver.

Consideration for Accessing the Management API

Note

We are working to replace the Management API with a language agnostic solution, see Management System

The described connection uses GraphBinary and the janusgraph-driver which doesn't allow accessing the internal JanusGraph components such as ManagementSystem. To access the ManagementSystem, you have to submit java-based scripts, see Submitting Scripts, or directly accessing JanusGraph by local opening a JanusGraph instance.