/*
* $Id: ChainingRouter.java 19739 2010-09-27 14:28:40Z tcarlson $
* --------------------------------------------------------------------------------------
* Copyright (c) MuleSoft, Inc. All rights reserved. http://www.mulesoft.com
*
* The software in this package is published under the terms of the CPAL v1.0
* license, a copy of which has been included with this distribution in the
* LICENSE.txt file.
*/
package org.mule.routing.outbound;
import org.mule.DefaultMuleEvent;
import org.mule.api.MuleEvent;
import org.mule.api.MuleException;
import org.mule.api.MuleMessage;
import org.mule.api.lifecycle.InitialisationException;
import org.mule.api.processor.MessageProcessor;
import org.mule.api.routing.CouldNotRouteOutboundMessageException;
import org.mule.api.routing.RoutePathNotFoundException;
import org.mule.api.routing.RoutingException;
import org.mule.config.i18n.CoreMessages;
import org.mule.transport.NullPayload;
/**
* <code>ChainingRouter</code> is used to pass a Mule event through multiple
* targets using the result of the first as the input for the second.
*/
public class ChainingRouter extends FilteringOutboundRouter
{
@Override
public void initialise() throws InitialisationException
{
super.initialise();
if (routes == null || routes.size() == 0)
{
throw new InitialisationException(CoreMessages.objectIsNull("targets"), this);
}
}
@Override
public MuleEvent route(MuleEvent event) throws RoutingException
{
MuleEvent resultToReturn = null;
if (routes == null || routes.size() == 0)
{
throw new RoutePathNotFoundException(CoreMessages.noEndpointsForRouter(), event, null);
}
final int endpointsCount = routes.size();
if (logger.isDebugEnabled())
{
logger.debug("About to chain " + endpointsCount + " targets.");
}
// need that ref for an error message
MessageProcessor endpoint = null;
try
{
MuleMessage intermediaryResult = event.getMessage();
for (int i = 0; i < endpointsCount; i++)
{
endpoint = getRoute(i, event);
// if it's not the last endpoint in the chain,
// enforce the synchronous call, otherwise we lose response
boolean lastEndpointInChain = (i == endpointsCount - 1);
if (logger.isDebugEnabled())
{
logger.debug("Sending Chained message '" + i + "': "
+ (intermediaryResult == null ? "null" : intermediaryResult.toString()));
}
if (!lastEndpointInChain)
{
MuleEvent event1 = sendRequest(event, intermediaryResult, endpoint, true);
MuleMessage localResult = event1 == null ? null : event1.getMessage();
// Need to propagate correlation info and replyTo, because there
// is no guarantee that an external system will preserve headers
// (in fact most will not)
if (localResult != null &&
// null result can be wrapped in a NullPayload
localResult.getPayload() != NullPayload.getInstance() &&
intermediaryResult != null)
{
processIntermediaryResult(localResult, intermediaryResult);
}
intermediaryResult = localResult;
if (logger.isDebugEnabled())
{
logger.debug("Received Chain result '" + i + "': "
+ (intermediaryResult != null ? intermediaryResult.toString() : "null"));
}
if (intermediaryResult == null || intermediaryResult.getPayload() == NullPayload.getInstance())
{
// if there was an error in the first link of the chain, make sure we propagate back
// any exception payloads alongside the NullPayload
resultToReturn = intermediaryResult == null ? null : new DefaultMuleEvent(intermediaryResult, event);
logger.warn("Chaining router cannot process any further targets. "
+ "There was no result returned from endpoint invocation: " + endpoint);
break;
}
}
else
{
// ok, the last call,
// use the 'sync/async' method parameter
resultToReturn = sendRequest(event, intermediaryResult, endpoint, true);
if (logger.isDebugEnabled())
{
MuleMessage resultMessage = resultToReturn == null ? null : resultToReturn.getMessage();
logger.debug("Received final Chain result '" + i + "': "
+ (resultMessage == null ? "null" : resultMessage.toString()));
}
}
}
}
catch (MuleException e)
{
throw new CouldNotRouteOutboundMessageException(event, endpoint, e);
}
return resultToReturn;
}
/**
* Process intermediary result of invocation. The method will be invoked
* <strong>only</strong> if both local and intermediary results are available
* (not null).
* <p/>
* Overriding methods must call <code>super(localResult, intermediaryResult)</code>,
* unless they are modifying the correlation workflow (if you know what that means,
* you know what you are doing and when to do it).
* <p/>
* Default implementation propagates
* the following properties:
* <ul>
* <li>correlationId
* <li>correlationSequence
* <li>correlationGroupSize
* <li>replyTo
* </ul>
* @param localResult result of the last endpoint invocation
* @param intermediaryResult the message travelling across the targets
*/
protected void processIntermediaryResult(MuleMessage localResult, MuleMessage intermediaryResult)
{
localResult.setCorrelationId(intermediaryResult.getCorrelationId());
localResult.setCorrelationSequence(intermediaryResult.getCorrelationSequence());
localResult.setCorrelationGroupSize(intermediaryResult.getCorrelationGroupSize());
localResult.setReplyTo(intermediaryResult.getReplyTo());
}
}