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.event;
018
019import org.apache.camel.Exchange;
020import org.apache.camel.Processor;
021import org.apache.camel.Producer;
022import org.apache.camel.impl.DefaultEndpoint;
023import org.apache.camel.impl.DefaultProducer;
024import org.apache.camel.processor.loadbalancer.LoadBalancer;
025import org.apache.camel.processor.loadbalancer.TopicLoadBalancer;
026import org.apache.camel.spi.UriEndpoint;
027import org.apache.camel.spi.UriPath;
028import org.apache.camel.util.ObjectHelper;
029import org.springframework.beans.BeansException;
030import org.springframework.context.ApplicationContext;
031import org.springframework.context.ApplicationContextAware;
032import org.springframework.context.ApplicationEvent;
033
034import static org.apache.camel.util.ObjectHelper.wrapRuntimeCamelException;
035
036/**
037 * An <a href="http://camel.apache.org/event.html">Event Endpoint</a>
038 * for working with Spring ApplicationEvents
039 *
040 * @version 
041 */
042@UriEndpoint(scheme = "spring-event", title = "Spring Event", syntax = "spring-event:name", consumerClass = EventConsumer.class, label = "spring,eventbus")
043public class EventEndpoint extends DefaultEndpoint implements ApplicationContextAware {
044    private LoadBalancer loadBalancer;
045    private ApplicationContext applicationContext;
046
047    @UriPath(description = "Name of endpoint")
048    private String name;
049
050    public EventEndpoint(String endpointUri, EventComponent component, String name) {
051        super(endpointUri, component);
052        this.applicationContext = component.getApplicationContext();
053        this.name = name;
054    }
055
056    /**
057     * <b>Note:</b> It is preferred to create endpoints using the associated
058     * component.
059     * @deprecated
060     */
061    @Deprecated
062    public EventEndpoint(String endpointUri) {
063        super(endpointUri);
064    }
065
066    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
067        this.applicationContext = applicationContext;
068    }
069
070    public ApplicationContext getApplicationContext() {
071        return applicationContext;
072    }
073
074    public String getName() {
075        return name;
076    }
077
078    public void setName(String name) {
079        this.name = name;
080    }
081
082    public boolean isSingleton() {
083        return true;
084    }
085
086    public Producer createProducer() throws Exception {
087        ObjectHelper.notNull(applicationContext, "applicationContext");
088        return new DefaultProducer(this) {
089            public void process(Exchange exchange) throws Exception {
090                ApplicationEvent event = toApplicationEvent(exchange);
091                applicationContext.publishEvent(event);
092            }
093        };
094    }
095
096    public EventConsumer createConsumer(Processor processor) throws Exception {
097        ObjectHelper.notNull(applicationContext, "applicationContext");
098        EventConsumer answer = new EventConsumer(this, processor);
099        configureConsumer(answer);
100        return answer;
101    }
102
103    public void onApplicationEvent(ApplicationEvent event) {
104        Exchange exchange = createExchange();
105        exchange.getIn().setBody(event);
106        try {
107            getLoadBalancer().process(exchange);
108        } catch (Exception e) {
109            throw wrapRuntimeCamelException(e);
110        }
111    }
112
113    public LoadBalancer getLoadBalancer() {
114        if (loadBalancer == null) {
115            loadBalancer = createLoadBalancer();
116        }
117        return loadBalancer;
118    }
119
120    public void setLoadBalancer(LoadBalancer loadBalancer) {
121        this.loadBalancer = loadBalancer;
122    }
123
124    @Override
125    public EventComponent getComponent() {
126        return (EventComponent) super.getComponent();
127    }
128
129    // Implementation methods
130    // -------------------------------------------------------------------------
131    public synchronized void consumerStarted(EventConsumer consumer) {
132        getComponent().consumerStarted(this);
133        getLoadBalancer().addProcessor(consumer.getProcessor());
134    }
135
136    public synchronized void consumerStopped(EventConsumer consumer) {
137        getComponent().consumerStopped(this);
138        getLoadBalancer().removeProcessor(consumer.getProcessor());
139    }
140
141    protected LoadBalancer createLoadBalancer() {
142        return new TopicLoadBalancer();
143    }
144
145    protected ApplicationEvent toApplicationEvent(Exchange exchange) {
146        ApplicationEvent event = exchange.getIn().getBody(ApplicationEvent.class);
147        if (event != null) {
148            return event;
149        }
150        return new CamelEvent(this, exchange);
151    }
152}