How to create and retrieve a graph database using java api in cassandra database

Question

I am trying to create a graph having nodes and edges with some weights in Cassandra database using Titan Graph api . so how to retrieve this graph so that I could visualize it.

rexster or gremlin is the solution for it.. ?? If it so.. Please tell me the process.

Answer 1

First note that TitanGraph uses the Blueprints API, thus the Titan API is the Blueprints API. As you are using Blueprints you can use Gremlin, Rexster or any part of the TinkerPop stack to process your graph.

How you visualize your graph once in Titan is dependent on the graph visualization tools you choose. If I assume you are using Gephi or similar tool that can consume GraphML, then the easiest way to get the data from Titan would be to open a Gremlin REPL, get a reference to the graph and just do:

g = TitanFactory.open(...)
g.saveGraphML('/tmp/my-graph.xml')

From there you could import my-graph.xml into Gephi and visualize it.

Answer 2

I have a 4 cluster cassandra setup. I run titan on top of it. I made this program which creates two nodes and then create an edge between them and finally queries and prints it.

    public static void main(String args[])
    {
        BaseConfiguration baseConfiguration = new BaseConfiguration();
        baseConfiguration.setProperty("storage.backend", "cassandra");
        baseConfiguration.setProperty("storage.hostname", "192.168.1.10");

        TitanGraph titanGraph = TitanFactory.open(baseConfiguration);

        Vertex rash = titanGraph.addVertex(null);
        rash.setProperty("userId", 1);
        rash.setProperty("username", "rash");
        rash.setProperty("firstName", "Rahul");
        rash.setProperty("lastName", "Chaudhary");
        rash.setProperty("birthday", 101);

        Vertex honey = titanGraph.addVertex(null);
        honey.setProperty("userId", 2);
        honey.setProperty("username", "honey");
        honey.setProperty("firstName", "Honey");
        honey.setProperty("lastName", "Anant");
        honey.setProperty("birthday", 201);

        Edge frnd = titanGraph.addEdge(null, rash, honey, "FRIEND");
        frnd.setProperty("since", 2011);

        titanGraph.commit();

        Iterable<Vertex> results = rash.query().labels("FRIEND").has("since", 2011).vertices();

        for(Vertex result : results)
        {
            System.out.println("Id: " + result.getProperty("userId"));
            System.out.println("Username: " + result.getProperty("username"));
            System.out.println("Name: " + result.getProperty("firstName") + " " + result.getProperty("lastName"));
        }
    }

My pom.xml, I just have this dependency:

<dependency>
    <groupId>com.thinkaurelius.titan</groupId>
    <artifactId>titan-cassandra</artifactId>
    <version>0.5.4</version>
</dependency>

I am running Cassandra 2.1.2.

I don’t know much on gremlin, but I believe Gremlin is the shell that you can use to query your database from the command line. Rexter is an API that you can use on top of any other API that uses Blueprints (like Titan), to make your query/code accessible to others via REST API. Since you want to use embedded Java with titan, you don’t need gremlin. With the dependency that I have stated, blueprint API comes with it and using that API (like I have done in my code), you can do everything with your graph.

You might find this cheatsheet useful. http://www.fromdev.com/2013/09/Gremlin-Example-Query-Snippets-Graph-DB.html