/**
*
* Copyright 2004 Protique Ltd
*
* 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.activemq.service.impl;
import org.activemq.broker.BrokerClient;
import org.activemq.filter.DestinationFilter;
import org.activemq.message.ActiveMQDestination;
import org.activemq.message.ActiveMQMessage;
import org.activemq.message.ConsumerInfo;
import org.activemq.service.DeadLetterPolicy;
import org.activemq.service.MessageContainerManager;
import javax.jms.Destination;
import javax.jms.JMSException;
import java.util.Iterator;
import java.util.Map;
/**
* Implements an initial image service where on subscription
* the client will recieve the last image that was previously cached.
* This is very useful in financial market data and in rapidly changing
* transient event models where you don't want to persist messages
* when you are away, but wish to cache the last image, per destination
* around so that when a new reliable consumer subscribes you receive the
* latest value you may have missed.
* <p/>
* This is especially true in finance with slow moving markets where you may
* have to wait a while for an update (or times when you subscribe after
* market close etc).
*
* @version $Revision: 1.1.1.1 $
*/
public class InitialImageMessageContainerManager extends ProxyMessageContainerManager {
private Map cache;
private boolean topic;
private DestinationFilter destinationFilter;
/**
* Creates a topic based initial image message container manager using the given destination filter
*
* @param delegate
* @param cache
* @param destinationFilter
*/
public InitialImageMessageContainerManager(MessageContainerManager delegate, Map cache, DestinationFilter destinationFilter) {
this(delegate, cache, true, destinationFilter);
}
public InitialImageMessageContainerManager(MessageContainerManager delegate, Map cache, boolean topic, DestinationFilter destinationFilter) {
super(delegate);
this.cache = cache;
this.topic = topic;
this.destinationFilter = destinationFilter;
}
public void addMessageConsumer(BrokerClient client, ConsumerInfo info) throws JMSException {
super.addMessageConsumer(client, info);
// lookup message for destination
ActiveMQDestination destination = info.getDestination();
if (isValid(destination)) {
if (destination.isWildcard()) {
DestinationFilter filter = DestinationFilter.parseFilter(destination);
sendMatchingInitialImages(client, info, filter);
}
else {
ActiveMQMessage message = null;
synchronized (cache) {
message = (ActiveMQMessage) cache.get(destination);
}
if (message != null) {
sendMessage(client, message);
}
}
}
}
public void sendMessage(BrokerClient client, ActiveMQMessage message) throws JMSException {
ActiveMQDestination destination = message.getJMSActiveMQDestination();
if (isValid(destination)) {
cache.put(destination, message);
}
super.sendMessage(client, message);
}
// Implementation methods
//-------------------------------------------------------------------------
protected void sendMatchingInitialImages(BrokerClient client, ConsumerInfo info, DestinationFilter filter) throws JMSException {
synchronized (cache) {
for (Iterator iter = cache.entrySet().iterator(); iter.hasNext();) {
Map.Entry entry = (Map.Entry) iter.next();
Destination destination = (Destination) entry.getKey();
if (filter.matches(destination)) {
ActiveMQMessage message = (ActiveMQMessage) entry.getValue();
sendMessage(client, message);
}
}
}
}
/**
* Does this message match the destinations on which initial image caching should be used
*
* @param destination
* @return true if the given destination should use initial image caching
* which is typically true if the message is a topic which may match
* an optional DestinationFilter
*/
protected boolean isValid(ActiveMQDestination destination) {
return destination.isTopic() == topic && (destinationFilter == null || destinationFilter.matches(destination));
}
}