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.NoTypeConversionAvailableException;
021    import org.apache.camel.Processor;
022    import org.apache.camel.Producer;
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.apache.camel.util.ObjectHelper;
028    import org.springframework.beans.BeansException;
029    import org.springframework.context.ApplicationContext;
030    import org.springframework.context.ApplicationContextAware;
031    import org.springframework.context.ApplicationEvent;
032    
033    import static org.apache.camel.util.ObjectHelper.wrapRuntimeCamelException;
034    
035    
036    /**
037     * An <a href="http://activemq.apache.org/camel/event.html">Event Endpoint</a>
038     * for working with Spring ApplicationEvents
039     *
040     * @version $Revision: 54154 $
041     */
042    public class EventEndpoint extends DefaultEndpoint<Exchange> implements ApplicationContextAware {
043        private LoadBalancer loadBalancer;
044        private ApplicationContext applicationContext;
045    
046        public EventEndpoint(String endpointUri, EventComponent component) {
047            super(endpointUri, component);
048            this.applicationContext = component.getApplicationContext();
049        }
050    
051        public EventEndpoint(String endpointUri) {
052            super(endpointUri);
053        }
054    
055        public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
056            this.applicationContext = applicationContext;
057        }
058    
059        public ApplicationContext getApplicationContext() {
060            return applicationContext;
061        }
062    
063        public boolean isSingleton() {
064            return true;
065        }
066    
067        public Producer<Exchange> createProducer() throws Exception {
068            ObjectHelper.notNull(getApplicationContext(), "applicationContext");
069            return new DefaultProducer<Exchange>(this) {
070                public void process(Exchange exchange) throws Exception {
071                    ApplicationEvent event = toApplicationEvent(exchange);
072                    getApplicationContext().publishEvent(event);
073                }
074            };
075        }
076    
077        public EventConsumer createConsumer(Processor processor) throws Exception {
078            return new EventConsumer(this, processor);
079        }
080    
081        public void onApplicationEvent(ApplicationEvent event) {
082            Exchange exchange = createExchange();
083            exchange.getIn().setBody(event);
084            try {
085                getLoadBalancer().process(exchange);
086            } catch (Exception e) {
087                throw wrapRuntimeCamelException(e);
088            }
089        }
090    
091        public LoadBalancer getLoadBalancer() {
092            if (loadBalancer == null) {
093                loadBalancer = createLoadBalancer();
094            }
095            return loadBalancer;
096        }
097    
098        public void setLoadBalancer(LoadBalancer loadBalancer) {
099            this.loadBalancer = loadBalancer;
100        }
101    
102        // Implementation methods
103        // -------------------------------------------------------------------------
104        public synchronized void consumerStarted(EventConsumer consumer) {
105            getLoadBalancer().addProcessor(consumer.getProcessor());
106        }
107    
108        public synchronized void consumerStopped(EventConsumer consumer) {
109            getLoadBalancer().removeProcessor(consumer.getProcessor());
110        }
111    
112        protected LoadBalancer createLoadBalancer() {
113            return new TopicLoadBalancer();
114        }
115    
116        protected ApplicationEvent toApplicationEvent(Exchange exchange) {
117            try {
118                ApplicationEvent event = exchange.getIn().getBody(ApplicationEvent.class);
119                if (event != null) {
120                    return event;
121                }
122            } catch (NoTypeConversionAvailableException ex) {
123                // ignore, handled below
124            }
125            return new CamelEvent(this, exchange);
126        }
127    }