AGSparqlGraphs.java
package com.franz.agbase.examples;
import com.franz.agbase.*;
public class AGSparqlGraphs {
/**
* Demonstrates how to perform named graph queries 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.
AllegroGraph ts = ags.renew("sparqlnamedgraphs", AGPaths.TRIPLE_STORES);
// Load N-Triples data into a named graph
URINode g = ts.createURI("http://example.org/kennedy/");
long n = ts.loadNTriples(AGPaths.dataSources("kennedy.ntriples"), g);
System.out.println("Loaded " + n + " triples.");
// Get some triples from a given graph g and show them.
TriplesIterator it = ts.getStatements(null, null, ts.createLiteral("Arnold"), g);
AGUtils.showTriples(it);
// Query for the first 20 place names ordered by name
String query =
"PREFIX ex: <http://example.org/kennedy/> " +
"SELECT ?name " +
"FROM NAMED <http://example.org/kennedy/> " +
"WHERE { GRAPH ex: { " +
"?place ex:name ?name " +
"}} " +
"ORDER BY ?name " +
"LIMIT 20";
// Query the store and show the results
SPARQLQuery sq = new SPARQLQuery();
sq.setTripleStore(ts);
sq.setQuery(query);
AGSparqlSelect.doSparqlSelect(sq);
// Close the store and disconnect from the server.
ts.closeTripleStore();
ags.disable();
}
}
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