/*=============================================================================*
* Copyright 2004 The Apache Software Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*=============================================================================*/
package org.apache.ws.resource.properties.query.impl;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.ws.resource.JndiConstants;
import org.apache.ws.resource.i18n.Keys;
import org.apache.ws.resource.i18n.MessagesImpl;
import org.apache.ws.resource.properties.ResourcePropertySet;
import org.apache.ws.resource.properties.query.ExpressionEvaluator;
import org.apache.ws.resource.properties.query.InvalidQueryExpressionException;
import org.apache.ws.resource.properties.query.QueryConstants;
import org.apache.ws.resource.properties.query.QueryEngine;
import org.apache.ws.resource.properties.query.QueryEvaluationErrorException;
import org.apache.ws.resource.properties.query.QueryExpression;
import org.apache.ws.resource.properties.query.UnknownQueryExpressionDialectException;
import org.apache.ws.resource.properties.query.xpath.impl.XalanXPathExpressionEvaluator;
import org.apache.ws.util.i18n.Messages;
import org.apache.ws.util.jndi.XmlBeanJndiUtils;
import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NameClassPair;
import javax.naming.NamingEnumeration;
import javax.naming.NamingException;
import java.net.URI;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
/**
* Executes queries on resource property sets. The engine looks for evaluators under the "wsrf/query/eval" JNDI
* context.
*
* @see ResourcePropertySet
*/
public class QueryEngineImpl
implements QueryEngine
{
/**
* DOCUMENT_ME
*/
private static final Log LOG =
LogFactory.getLog( QueryEngineImpl.class.getName( ) );
private static final Messages MSG = MessagesImpl.getInstance( );
private static String COTEXT_NAME_QUERY_EVALUATOR = JndiConstants.CONTEXT_NAME_WSRF + "/query/eval";
private Map m_evaluators = Collections.synchronizedMap( new HashMap( ) );
/**
* Creates a new {@link QueryEngineImpl} object.
*/
public QueryEngineImpl( )
{
refresh( );
}
/**
* @param dialect
*
* @return
*/
public ExpressionEvaluator getEvaluator( URI dialect )
{
return (ExpressionEvaluator) m_evaluators.get( dialect );
}
/**
* @see QueryEngine#executeQuery(org.apache.ws.resource.properties.query.QueryExpression,
* org.apache.ws.resource.properties.ResourcePropertySet)
*/
public Object executeQuery( QueryExpression queryExpr,
ResourcePropertySet resourcePropertySet )
throws UnknownQueryExpressionDialectException,
QueryEvaluationErrorException,
InvalidQueryExpressionException
{
if ( LOG.isDebugEnabled( ) )
{
LOG.debug( MSG.getMessage( Keys.EXEC_QUERY ) + ": " + queryExpr + MSG.getMessage( Keys.ON_RP_SET )
+ resourcePropertySet.getMetaData( ).getName( ).toString( ) );
}
return getEvaluator( queryExpr ).evaluate( queryExpr, resourcePropertySet );
}
/**
* @see QueryEngine#executeQuery(org.apache.ws.resource.properties.query.QueryExpression, Object)}
*/
public Object executeQuery( QueryExpression queryExpr,
Object evalContext )
throws UnknownQueryExpressionDialectException,
QueryEvaluationErrorException,
InvalidQueryExpressionException
{
return getEvaluator( queryExpr ).evaluate( queryExpr, evalContext );
}
/**
* Reinitializes the evaluators list from JNDI context. If any evaluators were added using {@link
* #registerEvaluator(ExpressionEvaluator) registerEvaluator()} function they will be lost.
*/
public synchronized void refresh( )
{
m_evaluators.clear( );
NamingEnumeration list = null;
try
{
Context initialContext = new InitialContext( );
try
{
list = initialContext.list( COTEXT_NAME_QUERY_EVALUATOR );
}
catch ( NamingException ne )
{
// ignore
}
if ( ( list != null ) && list.hasMore( ) )
{
while ( list.hasMore( ) )
{
NameClassPair pair = (NameClassPair) list.next( );
ExpressionEvaluator evaluator =
(ExpressionEvaluator) XmlBeanJndiUtils.lookup( initialContext,
COTEXT_NAME_QUERY_EVALUATOR + "/"
+ pair.getName( ), ExpressionEvaluator.class );
registerEvaluator( evaluator );
}
}
else
{
// nothing in JNDI - register a default evaluator for XPath 1.0...
registerEvaluator( QueryConstants.DIALECT_URI__XPATH1_0,
new XalanXPathExpressionEvaluator( ) );
}
}
catch ( Exception e )
{
LOG.error( MSG.getMessage( Keys.QUERY_ENG_INIT_ERROR, e ) );
}
finally
{
if ( list != null )
{
try
{
list.close( );
}
catch ( NamingException ne )
{
// intentionally ignored
}
}
}
}
/**
* DOCUMENT_ME
*
* @param evaluator DOCUMENT_ME
*/
public synchronized void registerEvaluator( ExpressionEvaluator evaluator )
{
URI[] dialects = evaluator.getSupportedDialects( );
for ( int i = 0; i < dialects.length; i++ )
{
m_evaluators.put( dialects[i], evaluator );
}
}
/**
* @param dialect
* @param evaluator
*
* @throws UnknownQueryExpressionDialectException
*
*/
public void registerEvaluator( URI dialect,
ExpressionEvaluator evaluator )
throws UnknownQueryExpressionDialectException
{
URI[] supportedDialects = evaluator.getSupportedDialects( );
boolean isSupportedDialect = false;
for ( int i = 0; i < supportedDialects.length; i++ )
{
if ( supportedDialects[i].equals( dialect ) )
{
isSupportedDialect = true;
}
}
if ( isSupportedDialect )
{
m_evaluators.put( dialect, evaluator );
}
else
{
throw new UnknownQueryExpressionDialectException( dialect );
}
}
private ExpressionEvaluator getEvaluator( QueryExpression queryExpr )
throws UnknownQueryExpressionDialectException
{
ExpressionEvaluator evaluator = getEvaluator( queryExpr.getDialect( ) );
if ( evaluator == null )
{
throw new UnknownQueryExpressionDialectException( queryExpr.getDialect( ) );
}
return evaluator;
}
}