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.processor.loadbalancer;
018    
019    import java.util.List;
020    
021    import org.apache.camel.AsyncCallback;
022    import org.apache.camel.Exchange;
023    import org.apache.camel.Processor;
024    
025    /**
026     * A {@link LoadBalancer} implementations which sends to all destinations
027     * (rather like JMS Topics). 
028     * 
029     * @version $Revision: 67691 $
030     *
031     */
032    public class TopicLoadBalancer extends LoadBalancerSupport {
033    
034        public void process(Exchange exchange) throws Exception {
035            List<Processor> list = getProcessors();
036            for (Processor processor : list) {
037                Exchange copy = copyExchangeStrategy(processor, exchange);
038                processor.process(copy);
039            }
040        }
041    
042        /**
043         * Strategy method to copy the exchange before sending to another endpoint.
044         * Derived classes such as the {@link org.apache.camel.processor.Pipeline Pipeline}
045         * will not clone the exchange
046         * 
047         * @param processor the processor that will send the exchange
048         * @param exchange  the exchange
049         * @return the current exchange if no copying is required such as for a
050         *         pipeline otherwise a new copy of the exchange is returned.
051         */
052        protected Exchange copyExchangeStrategy(Processor processor, Exchange exchange) {
053            return exchange.copy();
054        }
055    
056        public boolean process(Exchange exchange, AsyncCallback callback) {
057            List<Processor> list = getProcessors();
058            for (Processor processor : list) {
059                Exchange copy = copyExchangeStrategy(processor, exchange);
060                try {
061                    processor.process(copy);
062                } catch (Exception ex) {
063                    // We don't handle the exception here
064                }
065            }
066            callback.done(false);
067            return false;
068        }
069    }