AGSparqlBasicGraphPatterns.java
package com.franz.agbase.examples;
import com.franz.agbase.*;
public class AGSparqlBasicGraphPatterns {
/**
* Demonstrates matching of basic graph patterns 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);
// Add data to the store
ts.addStatement("<http://example.org/book/book1>",
"<http://purl.org/dc/elements/1.1/title>",
ts.createLiteral("SPARQL Tutorial"));
// Define the query string: a query with a single select variable
// and a single triple pattern in the graph pattern
String query =
"SELECT ?title " +
"WHERE {" +
"<http://example.org/book/book1> <http://purl.org/dc/elements/1.1/title> ?title ." +
"}";
// Query the store and show the results
SPARQLQuery sq = new SPARQLQuery();
sq.setTripleStore(ts);
sq.setQuery(query);
AGSparqlSelect.doSparqlSelect(sq);
// Register the foaf namespace
ts.registerNamespace("foaf", "http://xmlns.com/foaf/0.1/");
// Define any blank nodes you want to reuse
BlankNode a = (BlankNode)ts.createBNode("_:a");
BlankNode b = (BlankNode)ts.createBNode("_:b");
BlankNode c = (BlankNode)ts.createBNode("_:c");
// Add some more data to the store
ts.addStatement(a,"!foaf:name",ts.createLiteral("Johnny Lee Outlaw"));
ts.addStatement(a,"!foaf:mbox","<mailto:[email protected]>");
ts.addStatement(b,"!foaf:name",ts.createLiteral("Peter Goodguy"));
ts.addStatement(b,"!foaf:mbox","<mailto:[email protected]>");
ts.addStatement(c,"!foaf:mbox","<mailto:[email protected]>");
// A query with a namespace, multiple select variables, and
// multiple triple patterns in the graph pattern
query =
"PREFIX foaf: <http://xmlns.com/foaf/0.1/> " +
"SELECT ?name ?mbox " +
"WHERE " +
" { ?x foaf:name ?name . " +
" ?x foaf:mbox ?mbox }";
// Query the store and show the results
sq.setQuery(query);
AGSparqlSelect.doSparqlSelect(sq);
// Close the triple store and disconnect from the server.
ts.closeTripleStore();
ags.disable();
}
}
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