AGSparqlAsk.java

package com.franz.agbase.examples;

import com.franz.agbase.*;

public class AGSparqlAsk {

    /**
     * Demonstrates some basics of using ASK 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);
        
        // The briefest possible SPARQL query:
        String query = "ASK {}";
        
        // Query the store and show the result
        SPARQLQuery sq = new SPARQLQuery();
        boolean result = sq.ask(ts, query);
        System.out.println("Query: " + query);
        System.out.println("Result: " + result);
            
        // 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/>");

        query =
        "PREFIX foaf:    <http://xmlns.com/foaf/0.1/> " +
        "ASK  { ?x foaf:name  'Alice' }";
        
        // Query the store and show the result
        sq = new SPARQLQuery();
        result = sq.ask(ts, query);
        System.out.println("Query: " + query);
        System.out.println("Result: " + result);
        
        query =
        "PREFIX foaf:    <http://xmlns.com/foaf/0.1/> " +
        "ASK  { ?x foaf:name  'Fred' }";
            
        // Query the store and show the result
        sq = new SPARQLQuery();
        result = sq.ask(ts, query);
        System.out.println("Query: " + query);
        System.out.println("Result: " + result);
            
        // Close the triple store and disconnect from the server.
        ts.closeTripleStore();
        ags.disable();
    }

}

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