com.marklogic.semantics.jena.overview.html Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of marklogic-jena Show documentation
Adapter for using MarkLogic with the jena RDF Framework
There is a newer version: 4.0.0

MarkLogic Java API Overview

MarkLogic Jena

    marklogic-jena enables applications based on Apache Jena 2.13 to use
    MarkLogic as a persistence layer for triples, and as a source for SPARQL
    queries.  In addition to basic support for graph CRUD and SPARQL query and update, 
    marklogic-jena also exposes the following MarkLogic capabilities to the Jena
    framework:
    

        Transactions
        Variable bindings
        Inference (ruleset configuration)
        Combination of SPARQL with MarkLogic document query
        Optimized pagination of SPARQL result sets
    


Before Starting

    Ensure that you have the following information available for a MarkLogic instance:
    

        hostname
        port of an application server
        credentials to read/write/administer the database as needed
    
    If you need something to help you configure and deploy MarkLogic
    application servers, try 
    ml-gradle.

    Note: If you are starting with 8.0-4 MarkLogic installation on your local
    machine, the configuration of ml-gradle out of the box will set up a test
    server for you.

The API

Jena uses a {@link com.hp.hpl.jena.sparql.core.DatasetGraph} to model a set of RDF graphs.  To create a DatasetGraph that accesses MarkLogic, use {@link com.marklogic.semantics.jena.MarkLogicDatasetGraph}.  You may make a DatasetGraph instance from a Java Client API Database Client, or directly from the five-argument factory method.

import com.hp.hpl.jena.sparql.core.DatasetGraph;
import com.marklogic.client.DatabaseClient;
import com.marklogic.client.DatabaseClientFactory;
import com.marklogic.client.DatabaseClientFactory.Authentication;
import com.marklogic.semantics.jena.MarkLogicDatasetGraph;
import com.marklogic.semantics.jena.MarkLogicDatasetGraphFactory;
...

String host = "localhost";
String port = 9999;
String username = "username";
String password = "password";

// either make a DatabaseClient first
DatabseClient client = DatabaseClientFactory.newClient(
    host, port, username, password, Authentication.DIGEST);
    
DatasetGraph dsg;
dsg = MarkLogicDatasetGraphFactory.createDatasetGraph(client);

// or create dsg directly
dsg = MarkLogicDatasetGraphFactory.createDatasetGraph(
    host, port, username, password, Authentication.DIGEST);

// Do things with your DatasetGraph


Graph operations
Use Jena's CRUD operations to store, retrieve, merge or delete Graphs on the
MarkLogicDatasetGraph.
Node graphNode = NodeFactory.createURI("http://example.org/graphs/charles");

String turtle = "@prefix foaf:  ."
        + "@prefix :  ."
        +":charles a foaf:Person ; "
        + "        foaf:name \"Charles\" ;"
        + "        foaf:knows :jim ."
        + ":jim    a foaf:Person ;"
        + "        foaf:name \"Jim\" ;"
        + "        foaf:knows :charles .";

// make grpah locally
Graph graph = GraphFactory.createDefaultGraph();
RDFDataMgr.read(graph,  new StringReader(turtle), "", Lang.TURTLE);

// store in MarkLogic
dsg.addGraph(graphNode,  graph);

// Make a triple by hand
Graph moreTriples = GraphFactory.createDefaultGraph();
moreTriples.add(new Triple(
        NodeFactory.createURI("http://example.org/charles"),
        NodeFactory.createURI("http://example.org/hasDog"),
        NodeFactory.createURI("http://example.org/vashko")));

// merge it with the graph in MarkLogic
dsg.mergeGraph(graphNode, moreTriples);

// get the merged graph
Graph retrievedGraph = dsg.getGraph(graphNode);

// remove the graph
dsg.removeGraph(graphNode);

// remove all graphs
dsg.clear();



SPARQL Queries

QueryExecution execution = QueryExecutionFactory.create(
                "PREFIX foaf:  "
                +"select ?aname ?bname where { ?a foaf:knows ?b ."
                + "                    ?a foaf:name ?aname ."
                + "                    ?b foaf:name ?bname }", dsg.toDataset());
int n = 1;
for (ResultSet results = execution.execSelect();
        results.hasNext();
        n++) {
    QuerySolution solution = results.next();
    System.out.println("Solution #" + n ": "
            + solution.get("aname").asLiteral().getString()
            +" knows " 
            + solution.get("bname").asLiteral().getString());
}
dsg.close();


SPARQL Update

String insertData = "PREFIX foaf:  "
        + "PREFIX :  "
        +"INSERT DATA {GRAPH :g1 {"
        + ":charles a foaf:Person ; "
        + "        foaf:name \"Charles\" ;"
        + "        foaf:knows :jim ."
        + ":jim    a foaf:Person ;"
        + "        foaf:name \"Jim\" ;"
        + "        foaf:knows :charles ."
        + "} }";

UpdateRequest update = UpdateFactory.create(insertData);
UpdateProcessor processor = UpdateExecutionFactory.create(update, dsg);
processor.execute();

update = UpdateFactory.create("PREFIX :  DROP GRAPH :g1");
processor = UpdateExecutionFactory.create(update, dsg);
processor.execute();
dsg.close();