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;
018    
019    
020    
021    import java.util.ArrayList;
022    import java.util.Iterator;
023    import java.util.List;
024    
025    import org.apache.camel.Endpoint;
026    import org.apache.camel.Exchange;
027    import org.apache.camel.Expression;
028    import org.apache.camel.Processor;
029    import org.apache.camel.Producer;
030    import org.apache.camel.converter.ObjectConverter;
031    import org.apache.camel.impl.ProducerCache;
032    import org.apache.camel.impl.ServiceSupport;
033    import org.apache.camel.processor.aggregate.UseLatestAggregationStrategy;
034    import org.apache.camel.util.ExchangeHelper;
035    import static org.apache.camel.util.ObjectHelper.notNull;
036    
037    /**
038     * Implements a dynamic <a
039     * href="http://activemq.apache.org/camel/recipient-list.html">Recipient List</a>
040     * pattern where the list of actual endpoints to send a message exchange to are
041     * dependent on some dynamic expression.
042     *
043     * @version $Revision: 41822 $
044     */
045    public class RecipientList extends ServiceSupport implements Processor {
046        private final Expression<Exchange> expression;
047        private ProducerCache<Exchange> producerCache = new ProducerCache<Exchange>();
048    
049        public RecipientList(Expression<Exchange> expression) {
050            notNull(expression, "expression");
051            this.expression = expression;
052        }
053    
054        @Override
055        public String toString() {
056            return "RecipientList[" + expression + "]";
057        }
058    
059        public void process(Exchange exchange) throws Exception {
060            Object receipientList = expression.evaluate(exchange);
061            Iterator iter = ObjectConverter.iterator(receipientList);
062            List<Processor> processors = new ArrayList<Processor>();
063            while (iter.hasNext()) {
064                Object recipient = iter.next();
065                Endpoint<Exchange> endpoint = resolveEndpoint(exchange, recipient);
066                Producer<Exchange> producer = producerCache.getProducer(endpoint);
067                processors.add(producer);
068            }
069            MulticastProcessor mp = new MulticastProcessor(processors, new UseLatestAggregationStrategy());
070            mp.process(exchange);
071        }
072    
073        protected Endpoint<Exchange> resolveEndpoint(Exchange exchange, Object recipient) {
074            return ExchangeHelper.resolveEndpoint(exchange, recipient);
075        }
076    
077        protected void doStop() throws Exception {
078            producerCache.stop();
079        }
080    
081        protected void doStart() throws Exception {
082        }
083    }