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 */
017package org.apache.camel.component.vm;
018
019import java.util.HashMap;
020import java.util.Map;
021import java.util.concurrent.BlockingQueue;
022import java.util.concurrent.atomic.AtomicInteger;
023
024import org.apache.camel.Component;
025import org.apache.camel.Endpoint;
026import org.apache.camel.Exchange;
027import org.apache.camel.component.seda.BlockingQueueFactory;
028import org.apache.camel.component.seda.QueueReference;
029import org.apache.camel.component.seda.SedaComponent;
030
031/**
032 * The <a href="http://camel.apache.org/vm.html">VM component</a> is for asynchronous SEDA exchanges on a {@link BlockingQueue} 
033 * within the classloader tree containing the camel-core.jar.
034 *
035 * i.e. to handle communicating across CamelContext instances and possibly across web application contexts, providing that camel-core.jar is on the system classpath.
036 * 
037 * @version
038 */
039public class VmComponent extends SedaComponent {
040    protected static final Map<String, QueueReference> QUEUES = new HashMap<String, QueueReference>();
041    protected static final Map<String, VmEndpoint> ENDPOINTS = new HashMap<String, VmEndpoint>();
042    private static final AtomicInteger START_COUNTER = new AtomicInteger();
043
044    public VmComponent() {
045        super(VmEndpoint.class);
046    }
047
048    public VmComponent(Class<? extends Endpoint> endpointClass) {
049        super(endpointClass);
050    }
051
052    @Override
053    public Map<String, QueueReference> getQueues() {
054        return QUEUES;
055    }
056    
057    @Override
058    public QueueReference getQueueReference(String key) {
059        return QUEUES.get(key);
060    }
061
062    @Override
063    protected void doStart() throws Exception {
064        super.doStart();
065        START_COUNTER.incrementAndGet();
066    }
067
068    @Override
069    protected void doStop() throws Exception {
070        if (START_COUNTER.decrementAndGet() <= 0) {
071            // clear queues when no more vm components in use
072            getQueues().clear();
073            // also clear endpoints
074            ENDPOINTS.clear();
075        }
076    }
077
078    @Override
079    protected Endpoint createEndpoint(String uri, String remaining, Map<String, Object> parameters) throws Exception {
080        if (ENDPOINTS.containsKey(uri)) {
081            return ENDPOINTS.get(uri);
082        }
083
084        VmEndpoint answer = (VmEndpoint) super.createEndpoint(uri, remaining, parameters);
085
086        ENDPOINTS.put(uri, answer);
087        return answer;
088    }
089
090    @Override
091    protected VmEndpoint createEndpoint(String endpointUri, Component component, BlockingQueueFactory<Exchange> queueFactory, int concurrentConsumers) {
092        return new VmEndpoint(endpointUri, component, queueFactory, concurrentConsumers);
093    }
094
095    @Override
096    protected VmEndpoint createEndpoint(String endpointUri, Component component, BlockingQueue<Exchange> queue, int concurrentConsumers) {
097        return new VmEndpoint(endpointUri, component, queue, concurrentConsumers);
098    }
099}