/**
*
* Copyright 2005 LogicBlaze, Inc. http://www.logicblaze.com
*
* 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.servicemix.components.cache;
import org.servicemix.components.util.TransformComponentSupport;
import org.servicemix.components.util.MessageTransformer;
import org.servicemix.components.util.CopyTransformer;
import org.servicemix.expression.Expression;
import org.servicemix.expression.PropertyExpression;
import org.servicemix.jbi.NoOutMessageAvailableException;
import javax.jbi.JBIException;
import javax.jbi.messaging.Fault;
import javax.jbi.messaging.InOut;
import javax.jbi.messaging.MessageExchange;
import javax.jbi.messaging.MessagingException;
import javax.jbi.messaging.NormalizedMessage;
import java.util.Map;
/**
* Implements a caching layer on top of a service invocation to avoid calling an expensive remote service too often.
* The cache can be a simple Map based cache or a full <a href="http://www.jcp.org/en/jsr/detail?id=107">JCache</a> instance.
*
* @version $Revision: 496 $
*/
public class CacheComponent extends TransformComponentSupport {
public static final PropertyExpression KEY_PROPERTY_EXPRESSION = new PropertyExpression("org.servicemix.key");
private Map cache;
private Expression keyExpression = KEY_PROPERTY_EXPRESSION;
public Map getCache() {
return cache;
}
public void setCache(Map cache) {
this.cache = cache;
}
public Expression getKeyExpression() {
return keyExpression;
}
public void setKeyExpression(Expression keyExpression) {
this.keyExpression = keyExpression;
}
// Implementation methods
//-------------------------------------------------------------------------
protected void init() throws JBIException {
super.init();
if (cache == null) {
throw new JBIException("You must specify a cache property");
}
}
protected boolean transform(MessageExchange exchange, NormalizedMessage in, NormalizedMessage out) throws MessagingException {
Object key = keyExpression.evaluate(exchange, in);
if (key != null) {
NormalizedMessage message = (NormalizedMessage) cache.get(key);
if (message != null) {
getMessageTransformer().transform(exchange, message, out);
return true;
}
}
InOut inOut = getExchangeFactory().createInOutExchange();
NormalizedMessage request = inOut.createMessage();
getMessageTransformer().transform(exchange, in, request);
inOut.setInMessage(request);
getDeliveryChannel().sendSync(inOut);
NormalizedMessage response = inOut.getOutMessage();
Fault fault = inOut.getFault();
Exception error = inOut.getError();
if (fault != null) {
fail(exchange, fault);
}
else if (error != null) {
fail(exchange, error);
}
else if (response != null) {
getMessageTransformer().transform(exchange, response, out);
if (key != null) {
cache.put(key, response);
}
}
else {
throw new NoOutMessageAvailableException(exchange);
}
return true;
}
}