`/*
* (c) Copyright 2007, 2008 Hewlett-Packard Development Company, LP
* All rights reserved.
* [See end of file]
*/
package arq.examples.bgpmatching;
import com.hp.hpl.jena.rdf.model.Model;
import com.hp.hpl.jena.rdf.model.ModelFactory;
import com.hp.hpl.jena.rdf.model.Property;
import com.hp.hpl.jena.rdf.model.Resource;
import com.hp.hpl.jena.sparql.engine.main.StageGenerator;
import com.hp.hpl.jena.sparql.util.QueryExecUtils;
import com.hp.hpl.jena.sparql.util.StringUtils;
import com.hp.hpl.jena.query.*;
/** Example to execute a query but handle the
* basic graph patterns in the query in some special way.
* Stages are one step in executing a basic graph pattern (BGP).
* A StageGenerator builds a StageList and the stage list
* is executes with the output (a QueryIterator) of the previous
* stage fed int the current stage.
*/
public class StageAltMain
{
static String NS = "http://example/" ;
public static void main(String[] argv)
{
String[] queryString =
{
"PREFIX ns: <"+NS+">" ,
"SELECT ?v ",
"{ ?s ns:p1 'xyz' ;",
" ns:p2 ?v }"
} ;
// The stage generator to be used for a query execution
// is read from the context. There is a global context, which
// is cloned when a query execution object (query engine) is
// created.
// Normally, StageGenerators are chained - a new one inspects the
// execution request and sees if it handles it. If it does not,
// it sends the request to the stage generator that was already registered.
// The normal stage generator is registerd in the global context.
// This can be replaced, so that every query execution uses the
// alternative stage generator, or the cloned context can be
// alter so that just one query execution is affected.
// Change the stage generator for all queries ...
if ( false )
{
StageGenerator origStageGen = (StageGenerator)ARQ.getContext().get(ARQ.stageGenerator) ;
StageGenerator stageGenAlt = new StageGeneratorAlt(origStageGen) ;
ARQ.getContext().set(ARQ.stageGenerator, stageGenAlt) ;
}
Query query = QueryFactory.create( StringUtils.join("\n", queryString)) ;
QueryExecution engine = QueryExecutionFactory.create(query, makeData()) ;
// ... or set on a per-execution basis.
if ( true )
{
StageGenerator origStageGen = (StageGenerator)engine.getContext().get(ARQ.stageGenerator) ;
StageGenerator stageGenAlt = new StageGeneratorAlt(origStageGen) ;
engine.getContext().set(ARQ.stageGenerator, stageGenAlt) ;
}
QueryExecUtils.executeQuery(query, engine) ;
}
private static Model makeData()
{
Model model = ModelFactory.createDefaultModel() ;
Resource r = model.createResource(NS+"r") ;
Property p1 = model.createProperty(NS+"p1") ;
Property p2 = model.createProperty(NS+"p2") ;
model.add(r, p1, "xyz") ;
model.add(r, p2, "abc") ;
return model ;
}
}
/*
* (c) Copyright 2007, 2008 Hewlett-Packard Development Company, LP
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/`