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.event;
018    
019    import org.apache.camel.Exchange;
020    import org.apache.camel.Processor;
021    import org.apache.camel.Producer;
022    import org.apache.camel.RuntimeCamelException;
023    import org.apache.camel.impl.DefaultEndpoint;
024    import org.apache.camel.impl.DefaultExchange;
025    import org.apache.camel.impl.DefaultProducer;
026    import org.apache.camel.processor.loadbalancer.LoadBalancer;
027    import org.apache.camel.processor.loadbalancer.TopicLoadBalancer;
028    
029    import org.springframework.context.ApplicationContext;
030    import org.springframework.context.ApplicationEvent;
031    
032    /**
033     * An <a href="http://activemq.apache.org/camel/event.html">Event Endpoint</a>
034     * for working with Spring ApplicationEvents
035     * 
036     * @version $Revision: 630591 $
037     */
038    public class EventEndpoint extends DefaultEndpoint<Exchange> {
039        private final EventComponent component;
040        private LoadBalancer loadBalancer;
041    
042        public EventEndpoint(String endpointUri, EventComponent component) {
043            super(endpointUri, component);
044            this.component = component;
045        }
046    
047        @Override
048        public EventComponent getComponent() {
049            return component;
050        }
051    
052        public ApplicationContext getApplicationContext() {
053            return getComponent().getApplicationContext();
054        }
055    
056        public boolean isSingleton() {
057            return true;
058        }
059    
060        public Producer<Exchange> createProducer() throws Exception {
061            return new DefaultProducer<Exchange>(this) {
062                public void process(Exchange exchange) throws Exception {
063                    ApplicationEvent event = toApplicationEvent(exchange);
064                    getApplicationContext().publishEvent(event);
065                }
066            };
067        }
068    
069        public EventConsumer createConsumer(Processor processor) throws Exception {
070            return new EventConsumer(this, processor);
071        }
072    
073        public void onApplicationEvent(ApplicationEvent event) {
074            Exchange exchange = createExchange();
075            exchange.getIn().setBody(event);
076            try {
077                getLoadBalancer().process(exchange);
078            } catch (Exception e) {
079                throw new RuntimeCamelException(e);
080            }
081        }
082    
083        public LoadBalancer getLoadBalancer() {
084            if (loadBalancer == null) {
085                loadBalancer = createLoadBalancer();
086            }
087            return loadBalancer;
088        }
089    
090        public void setLoadBalancer(LoadBalancer loadBalancer) {
091            this.loadBalancer = loadBalancer;
092        }
093    
094        // Implementation methods
095        // -------------------------------------------------------------------------
096        public synchronized void consumerStarted(EventConsumer consumer) {
097            getLoadBalancer().addProcessor(consumer.getProcessor());
098        }
099    
100        public synchronized void consumerStopped(EventConsumer consumer) {
101            getLoadBalancer().removeProcessor(consumer.getProcessor());
102        }
103    
104        protected LoadBalancer createLoadBalancer() {
105            return new TopicLoadBalancer();
106        }
107    
108        protected ApplicationEvent toApplicationEvent(Exchange exchange) {
109            ApplicationEvent event = exchange.getIn().getBody(ApplicationEvent.class);
110            if (event == null) {
111                event = new CamelEvent(this, exchange);
112            }
113            return event;
114        }
115    }