de.fuberlin.wiwiss.wiqa.engine
Class WIQAQueryEngine

java.lang.Object
  com.hp.hpl.jena.query.engine1.QueryEngine
      de.fuberlin.wiwiss.wiqa.engine.WIQAQueryEngine

All Implemented Interfaces:

QueryExecution

public class WIQAQueryEngine

extends QueryEngine

A customized QueryEngine that adds those processing stages that cannot be expressed as an ARQ query. This is done by modifying the ARQ query engine's query plan. The following stages are added into the plan:

• PlanExplain
• TODO: Count, explainable functions, explainable extensions

When the modified plan is executed, ARQ will automatically instantiate and execute the query iterators corresponding to these plan elements (for example, QueryIterExplain). These iterators implement the actual functionality of generating explanations, rejecting bindings that don't satisfy count constraints etc.

Version:

$Id: WIQAQueryEngine.java,v 1.5 2006/06/12 21:06:25 cyganiak Exp $

Author:

Richard Cyganiak (richard@cyganiak.de)

Field Summary

static Symbol	CONTEXT_VARIABLES Internal key used in the ExecutionContext for ARQ
static Symbol	EXPLANATION Internal key used in the ExecutionContext for ARQ
static Symbol	EXPLANATION_STORE Internal key used in the ExecutionContext for ARQ

Constructor Summary

WIQAQueryEngine(Dataset dataset, Policy policy, QuerySolution binding, ExplanationCache cache)

Method Summary

protected PlanElement	makePlanForQueryPattern(Plan plan) Use CustomQueryCompiler instead of ARQ's QueryCompilerVisitor to generate the query plan
protected PlanElement	queryPlanHook(Plan plan, PlanElement planElt) Add count and explain stages to end of query plan

Methods inherited from class com.hp.hpl.jena.query.engine1.QueryEngine

abort, close, execAsk, execConstruct, execDescribe, execSelect, getContext, getDataset, getPlan, getQuery, init, setDataset, setFileManager, setInitialBinding

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

EXPLANATION_STORE

public static final Symbol EXPLANATION_STORE

Internal key used in the ExecutionContext for ARQ

EXPLANATION

public static final Symbol EXPLANATION

Internal key used in the ExecutionContext for ARQ

CONTEXT_VARIABLES

public static final Symbol CONTEXT_VARIABLES

Internal key used in the ExecutionContext for ARQ

Constructor Detail

WIQAQueryEngine

public WIQAQueryEngine(Dataset dataset,
                       Policy policy,
                       QuerySolution binding,
                       ExplanationCache cache)

Method Detail

makePlanForQueryPattern

protected PlanElement makePlanForQueryPattern(Plan plan)

Use CustomQueryCompiler instead of ARQ's QueryCompilerVisitor to generate the query plan

queryPlanHook

protected PlanElement queryPlanHook(Plan plan,
                                    PlanElement planElt)

Add count and explain stages to end of query plan