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.processor.loadbalancer;
018
019import java.util.List;
020
021import org.apache.camel.AsyncCallback;
022import org.apache.camel.Exchange;
023import org.apache.camel.Processor;
024
025/**
026 * A {@link LoadBalancer} implementations which sends to all destinations
027 * (rather like JMS Topics).
028 * <p/>
029 * The {@link org.apache.camel.processor.MulticastProcessor} is more powerful as it offers
030 * option to run in parallel and decide whether or not to stop on failure etc.
031 *
032 * @version 
033 */
034public class TopicLoadBalancer extends LoadBalancerSupport {
035
036    public boolean process(final Exchange exchange, final AsyncCallback callback) {
037        List<Processor> list = getProcessors();
038        // too hard to do multiple async, so we do it sync
039        for (Processor processor : list) {
040            try {
041                Exchange copy = copyExchangeStrategy(processor, exchange);
042                processor.process(copy);
043            } catch (Throwable e) {
044                exchange.setException(e);
045                // stop on failure
046                break;
047            }
048        }
049        callback.done(true);
050        return true;
051    }
052
053    /**
054     * Strategy method to copy the exchange before sending to another endpoint.
055     * Derived classes such as the {@link org.apache.camel.processor.Pipeline Pipeline}
056     * will not clone the exchange
057     *
058     * @param processor the processor that will send the exchange
059     * @param exchange  the exchange
060     * @return the current exchange if no copying is required such as for a
061     *         pipeline otherwise a new copy of the exchange is returned.
062     */
063    protected Exchange copyExchangeStrategy(Processor processor, Exchange exchange) {
064        return exchange.copy();
065    }
066
067    public String toString() {
068        return "TopicLoadBalancer";
069    }
070}