AGFederationRangeQueries.java

package com.franz.agbase.examples;

import com.franz.agbase.*;

public class AGFederationRangeQueries {

    /**
     * Demonstrates a range query on a federated store. 
     *
     * @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);
        }

        // Register your namespaces
        ags.registerNamespace("ex","http://example.org/");
        
        // Create triple stores
        AllegroGraph ts1 = ags.renew("store1", AGPaths.TRIPLE_STORES);
        AllegroGraph ts2 = ags.renew("store2", AGPaths.TRIPLE_STORES);

        // Create a federated store consisting of the first 2 open stores above 
        AllegroGraph[] parts = {ts1,ts2};
        AllegroGraph fed = ags.federate("federation", parts, true);
        
        // Populate the leaf stores
        // Encoded literals are necessary when performing range queries 
        ts1.addStatement("!ex:person1","!ex:age", ts1.createEncodedLiteral(28,"int"));
        ts1.addStatement("!ex:person2","!ex:age", ts1.createEncodedLiteral(30,"int"));
        ts1.addStatement("!ex:person3","!ex:age", ts1.createEncodedLiteral(32,"int"));
        ts2.addStatement("!ex:person4","!ex:age", ts2.createEncodedLiteral(40,"int"));
        ts2.addStatement("!ex:person5","!ex:age", ts2.createEncodedLiteral(42,"int"));
        
        // Retrieve triples by matching a range of objects
        EncodedLiteral low = fed.createEncodedLiteral(30,"int");
        EncodedLiteral high = fed.createEncodedLiteral(40,"int");
        System.out.println("Retrieving triples with range 30 <= ex:age <= 40");
        TriplesIterator it = fed.getStatements(null, "!ex:age", low, high, null, null);
        AGUtils.showTriples(it);

        // Close the triple store and disconnect from the server
        fed.closeTripleStore();
        ts2.closeTripleStore();
        ts1.closeTripleStore();
        ags.disable();
    }

}

Up | Next

Copyright © 2014 Franz Inc., All Rights Reserved | Privacy Statement
Delicious Google Buzz Twitter Google+