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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();

    }



}
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