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.DefaultProducer;
025    import org.apache.camel.processor.loadbalancer.LoadBalancer;
026    import org.apache.camel.processor.loadbalancer.TopicLoadBalancer;
027    import org.springframework.beans.BeansException;
028    import org.springframework.context.ApplicationContext;
029    import org.springframework.context.ApplicationContextAware;
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: 41334 $
037     */
038    public class EventEndpoint extends DefaultEndpoint<Exchange> implements ApplicationContextAware {
039        private LoadBalancer loadBalancer;
040        private ApplicationContext applicationContext;
041    
042        public EventEndpoint(String endpointUri, EventComponent component) {
043            super(endpointUri, component);
044            this.applicationContext = component.getApplicationContext();
045        }
046    
047        public EventEndpoint(String endpointUri) {
048            super(endpointUri);
049        }
050    
051        public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
052            this.applicationContext = applicationContext;
053        }
054    
055        public ApplicationContext getApplicationContext() {
056            return applicationContext;
057        }
058    
059        public boolean isSingleton() {
060            return true;
061        }
062    
063        public Producer<Exchange> createProducer() throws Exception {
064            return new DefaultProducer<Exchange>(this) {
065                public void process(Exchange exchange) throws Exception {
066                    ApplicationEvent event = toApplicationEvent(exchange);
067                    getApplicationContext().publishEvent(event);
068                }
069            };
070        }
071    
072        public EventConsumer createConsumer(Processor processor) throws Exception {
073            return new EventConsumer(this, processor);
074        }
075    
076        public void onApplicationEvent(ApplicationEvent event) {
077            Exchange exchange = createExchange();
078            exchange.getIn().setBody(event);
079            try {
080                getLoadBalancer().process(exchange);
081            } catch (Exception e) {
082                throw new RuntimeCamelException(e);
083            }
084        }
085    
086        public LoadBalancer getLoadBalancer() {
087            if (loadBalancer == null) {
088                loadBalancer = createLoadBalancer();
089            }
090            return loadBalancer;
091        }
092    
093        public void setLoadBalancer(LoadBalancer loadBalancer) {
094            this.loadBalancer = loadBalancer;
095        }
096    
097        // Implementation methods
098        // -------------------------------------------------------------------------
099        public synchronized void consumerStarted(EventConsumer consumer) {
100            getLoadBalancer().addProcessor(consumer.getProcessor());
101        }
102    
103        public synchronized void consumerStopped(EventConsumer consumer) {
104            getLoadBalancer().removeProcessor(consumer.getProcessor());
105        }
106    
107        protected LoadBalancer createLoadBalancer() {
108            return new TopicLoadBalancer();
109        }
110    
111        protected ApplicationEvent toApplicationEvent(Exchange exchange) {
112            ApplicationEvent event = exchange.getIn().getBody(ApplicationEvent.class);
113            if (event == null) {
114                event = new CamelEvent(this, exchange);
115            }
116            return event;
117        }
118    
119    }