Using the Java API

As Gaffer is written in Java there is native support to allow use of all its public classes. Using Gaffer via the Java interface does differ from the REST API and gafferpy but is fully featured with extensive Javadocs. However, you will need to be familiar with writing and running Java code in order to utilise this form of the API.

Querying a Graph

Using Java to query a graph, unlike the other APIs, requires a reference to a Graph object that essentially represents a graph.

With the other APIs you would connect directly to a running instance via the REST interface; however, to do this with Java you would need to configure a Graph object with a proxy store.

The following example uses the ProxyStore.Builder() to configure a Graph to connect to the required address (in this case http://localhost:8080/rest).

Graph graph = new Graph.Builder()
    .store(new ProxyStore.Builder()
            .graphId(uniqueNameOfYourGraph)
            .host("localhost")
            .port(8080)
            .contextRoot("rest")
            .build())
    .build();

Once the connection to a graph is made you can run queries and operations on it using the available classes and builders.

The following operation chain gets all the elements in the graph then will count them and store the result in a Long.

OperationChain<Long> countAllElements = new OperationChain.Builder()
    .first(new GetAllElements())
    .then(new Count<>())
    .build();

Long result = graph.execute(countAllElements, user);

If you're interested in learning more about the Graph class please see the developers guide on the subject.

Note

One other thing to note about the Java API is that the execute() method requires you to have a User. This is part of Gaffer's fine grain security, see the admin guide for more information.