HBase can be run as a standalone database on the same local host as JanusGraph and the end-user application. In this model, JanusGraph and HBase communicate with one another via a localhost socket. Running JanusGraph over HBase requires the following setup steps:

$ ./bin/start-hbase.sh
starting master, logging to ../logs/hbase-master-machine-name.local.out

Now, you can create an HBase JanusGraph as follows:

JanusGraph graph = JanusGraphFactory.build()
	.set("storage.backend", "hbase")
	.open();

Note, that you do not need to specify a hostname since a localhost connection is attempted by default. Also, in the Gremlin Console, you can not define the type of the variables conf and g. Therefore, simply leave off the type declaration.

When the graph needs to scale beyond the confines of a single machine, then HBase and JanusGraph are logically separated into different machines. In this model, the HBase cluster maintains the graph representation and any number of JanusGraph instances maintain socket-based read/write access to the HBase cluster. The end-user application can directly interact with JanusGraph within the same JVM as JanusGraph.

For example, suppose we have a running HBase cluster with a ZooKeeper quorum composed of three machines at IP address 77.77.77.77, 77.77.77.78, and 77.77.77.79, then connecting JanusGraph with the cluster is accomplished as follows:

JanusGraph g = JanusGraphFactory.build()
	.set("storage.backend", "hbase")
	.set("storage.hostname", "77.77.77.77, 77.77.77.78, 77.77.77.79")
	.open();

storage.hostname accepts a comma separated list of IP addresses and hostname for any subset of machines in the HBase cluster JanusGraph should connect to. Also, in the Gremlin Console, you can not define the type of the variables conf and g. Therefore, simply leave off the type declaration.

Finally, Gremlin Server can be wrapped around each JanusGraph instance defined in the previous subsection. In this way, the end-user application need not be a Java-based application as it can communicate with Gremlin Server as a client. This type of deployment is great for polyglot architectures where various components written in different languages need to reference and compute on the graph.

http://gremlin-server.janusgraph.machine1/mygraph/vertices/1
http://gremlin-server.janusgraph.machine2/mygraph/tp/gremlin?script=g.v(1).out('follows').out('created')

In this case, each Gremlin Server would be configured to connect to the HBase cluster. The following shows the graph specific fragment of the Gremlin Server configuration. Refer to Chapter 7, JanusGraph Server for a complete example and more information on how to configure the server.

...
graphs: {
  g: conf/janusgraph-hbase.properties}
plugins:
  - janusgraph.imports
...