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.processor.loadbalancer.LoadBalancer;
023import org.apache.camel.processor.loadbalancer.TopicLoadBalancer;
024import org.apache.camel.spi.UriEndpoint;
025import org.apache.camel.spi.UriPath;
026import org.apache.camel.support.DefaultEndpoint;
027import org.apache.camel.support.DefaultProducer;
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.RuntimeCamelException.wrapRuntimeCamelException;
035
036/**
037 * The spring-event component allows to listen for Spring Application Events.
038 */
039@UriEndpoint(firstVersion = "1.4.0", scheme = "spring-event", title = "Spring Event", syntax = "spring-event:name", label = "spring,eventbus")
040public class EventEndpoint extends DefaultEndpoint implements ApplicationContextAware {
041    private LoadBalancer loadBalancer;
042    private ApplicationContext applicationContext;
043
044    @UriPath(description = "Name of endpoint")
045    private String name;
046
047    public EventEndpoint(String endpointUri, EventComponent component, String name) {
048        super(endpointUri, component);
049        this.applicationContext = component.getApplicationContext();
050        this.name = name;
051    }
052
053    @Override
054    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
055        this.applicationContext = applicationContext;
056    }
057
058    public ApplicationContext getApplicationContext() {
059        return applicationContext;
060    }
061
062    public String getName() {
063        return name;
064    }
065
066    public void setName(String name) {
067        this.name = name;
068    }
069
070    @Override
071    public Producer createProducer() throws Exception {
072        ObjectHelper.notNull(applicationContext, "applicationContext");
073        return new DefaultProducer(this) {
074            public void process(Exchange exchange) throws Exception {
075                ApplicationEvent event = toApplicationEvent(exchange);
076                applicationContext.publishEvent(event);
077            }
078        };
079    }
080
081    @Override
082    public EventConsumer createConsumer(Processor processor) throws Exception {
083        ObjectHelper.notNull(applicationContext, "applicationContext");
084        EventConsumer answer = new EventConsumer(this, processor);
085        configureConsumer(answer);
086        return answer;
087    }
088
089    public void onApplicationEvent(ApplicationEvent event) {
090        Exchange exchange = createExchange();
091        exchange.getIn().setBody(event);
092        try {
093            getLoadBalancer().process(exchange);
094        } catch (Exception e) {
095            throw wrapRuntimeCamelException(e);
096        }
097    }
098
099    public LoadBalancer getLoadBalancer() {
100        if (loadBalancer == null) {
101            loadBalancer = createLoadBalancer();
102        }
103        return loadBalancer;
104    }
105
106    public void setLoadBalancer(LoadBalancer loadBalancer) {
107        this.loadBalancer = loadBalancer;
108    }
109
110    @Override
111    public EventComponent getComponent() {
112        return (EventComponent) super.getComponent();
113    }
114
115    // Implementation methods
116    // -------------------------------------------------------------------------
117    public synchronized void consumerStarted(EventConsumer consumer) {
118        getComponent().consumerStarted(this);
119        getLoadBalancer().addProcessor(consumer.getAsyncProcessor());
120    }
121
122    public synchronized void consumerStopped(EventConsumer consumer) {
123        getComponent().consumerStopped(this);
124        getLoadBalancer().removeProcessor(consumer.getAsyncProcessor());
125    }
126
127    protected LoadBalancer createLoadBalancer() {
128        return new TopicLoadBalancer();
129    }
130
131    protected ApplicationEvent toApplicationEvent(Exchange exchange) {
132        ApplicationEvent event = exchange.getIn().getBody(ApplicationEvent.class);
133        if (event != null) {
134            return event;
135        }
136        return new CamelEvent(this, exchange);
137    }
138}