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AGSparqlDescribe.java

package com.franz.ag.examples;



import com.franz.ag.*;



public class AGSparqlDescribe {



    /**

     * Demonstrates some basics of using DESCRIBE in SPARQL

     * 

     * @param args unused

     * @throws AllegroGraphException 

     */

    public static void main(String[] args) throws AllegroGraphException {

        

        // Connect to server, which must already be running.

        AllegroGraphConnection ags = new AllegroGraphConnection();

        try {

            ags.enable();

        } catch (Exception e) {

            throw new AllegroGraphException("Server connection problem", e);

        }

        

        // Create fresh triple-store for this example.

        AllegroGraph ts = ags.renew("sparql", AGPaths.TRIPLE_STORES);

                

        // Register any namespaces

        ts.registerNamespace("foaf", "http://xmlns.com/foaf/0.1/");



        // Define blank nodes

        BlankNode a = (BlankNode)ts.createBNode("_:a");

        BlankNode b = (BlankNode)ts.createBNode("_:b");

        

        // Add some data to the store

        ts.addStatement(a,"!rdf:type","!foaf:Person");

        ts.addStatement(a,"!foaf:name",ts.createLiteral("Alice"));

        ts.addStatement(a,"!foaf:mbox","<mailto:alice@example.com>");

        ts.addStatement(a,"!foaf:mbox","<mailto:alice@work.example>");

        ts.addStatement(b,"!rdf:type","!foaf:Person");

        ts.addStatement(b,"!foaf:name",ts.createLiteral("Bob"));

        ts.addStatement(b,"!foaf:homepage","<http://work.example.org/alice/>");



        // This query requests that an RDF graph be returned containing

        // data describing resources that have the specified foaf:mbox.

        String query = 

        "PREFIX foaf:   <http://xmlns.com/foaf/0.1/> " +

        "DESCRIBE ?x " +

        "WHERE    { ?x foaf:mbox <mailto:alice@example.com> } ";

        

        // Query the store and show the resulting graph

        SPARQLQuery sq = new SPARQLQuery();

        Cursor cc = sq.describe(ts,query);

        AGUtils.showTriples(cc);

        

        // Close the triple store and disconnect from the server.

        ts.closeTripleStore();

        ags.disable();

    }



}
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