001 /**
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017 package org.apache.camel.component.vm;
018
019 import java.util.HashMap;
020 import java.util.Map;
021 import java.util.concurrent.BlockingQueue;
022 import java.util.concurrent.atomic.AtomicInteger;
023
024 import org.apache.camel.Endpoint;
025 import org.apache.camel.Exchange;
026 import org.apache.camel.component.seda.SedaComponent;
027 import org.apache.camel.component.seda.SedaEndpoint;
028
029 /**
030 * An implementation of the <a href="http://camel.apache.org/vm.html">VM components</a>
031 * for asynchronous SEDA exchanges on a {@link BlockingQueue} within the classloader tree containing
032 * the camel-core.jar. i.e. to handle communicating across CamelContext instances and possibly across
033 * web application contexts, providing that camel-core.jar is on the system classpath.
034 *
035 * @version $Revision: 747062 $
036 */
037 public class VmComponent extends SedaComponent {
038 protected static final Map<String, BlockingQueue> QUEUES = new HashMap<String, BlockingQueue>();
039 private static final AtomicInteger START_COUNTER = new AtomicInteger();
040
041 @Override
042 protected Endpoint createEndpoint(String uri, String remaining, Map parameters) throws Exception {
043 BlockingQueue<Exchange> blockingQueue = getBlockingQueue(uri, parameters);
044 return new SedaEndpoint(uri, this, blockingQueue);
045 }
046
047 @SuppressWarnings("unchecked")
048 protected BlockingQueue<Exchange> getBlockingQueue(String uri, Map parameters) {
049 synchronized (QUEUES) {
050 BlockingQueue<Exchange> answer = QUEUES.get(uri);
051 if (answer == null) {
052 answer = createQueue(uri, parameters);
053 QUEUES.put(uri, answer);
054 }
055 return answer;
056 }
057 }
058
059 @Override
060 protected void doStart() throws Exception {
061 super.doStart();
062 START_COUNTER.incrementAndGet();
063 }
064
065 @Override
066 protected void doStop() throws Exception {
067 super.doStop();
068 if (START_COUNTER.decrementAndGet() == 0) {
069 synchronized (QUEUES) {
070 for (BlockingQueue q : QUEUES.values()) {
071 q.clear();
072 }
073 QUEUES.clear();
074 }
075 }
076 }
077
078 }