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    import java.util.ArrayList;
020    import java.util.Iterator;
021    import java.util.List;
022    
023    import org.apache.camel.Endpoint;
024    import org.apache.camel.Exchange;
025    import org.apache.camel.Expression;
026    import org.apache.camel.Processor;
027    import org.apache.camel.Producer;
028    import org.apache.camel.impl.ProducerCache;
029    import org.apache.camel.impl.ServiceSupport;
030    import org.apache.camel.processor.aggregate.UseLatestAggregationStrategy;
031    import org.apache.camel.util.ExchangeHelper;
032    import org.apache.camel.util.ObjectHelper;
033    import static org.apache.camel.util.ObjectHelper.notNull;
034    
035    /**
036     * Implements a dynamic <a
037     * href="http://activemq.apache.org/camel/recipient-list.html">Recipient List</a>
038     * pattern where the list of actual endpoints to send a message exchange to are
039     * dependent on some dynamic expression.
040     *
041     * @version $Revision: 52589 $
042     */
043    public class RecipientList extends ServiceSupport implements Processor {
044        private final Expression<Exchange> expression;
045        private ProducerCache<Exchange> producerCache = new ProducerCache<Exchange>();
046    
047        public RecipientList(Expression<Exchange> expression) {
048            notNull(expression, "expression");
049            this.expression = expression;
050        }
051    
052        @Override
053        public String toString() {
054            return "RecipientList[" + expression + "]";
055        }
056    
057        public void process(Exchange exchange) throws Exception {
058            Object receipientList = expression.evaluate(exchange);
059            sendToRecipientList(exchange, receipientList);
060        }
061    
062        /**
063         * Sends the given exchange to the recipient list
064         */
065        public void sendToRecipientList(Exchange exchange, Object receipientList) throws Exception {
066            Iterator iter = ObjectHelper.createIterator(receipientList);
067            List<Processor> processors = new ArrayList<Processor>();
068            while (iter.hasNext()) {
069                Object recipient = iter.next();
070                Endpoint<Exchange> endpoint = resolveEndpoint(exchange, recipient);
071                Producer<Exchange> producer = producerCache.getProducer(endpoint);
072                processors.add(producer);
073            }
074            MulticastProcessor mp = new MulticastProcessor(processors, new UseLatestAggregationStrategy());
075            mp.process(exchange);
076        }
077    
078        protected Endpoint<Exchange> resolveEndpoint(Exchange exchange, Object recipient) {
079            return ExchangeHelper.resolveEndpoint(exchange, recipient);
080        }
081    
082        protected void doStop() throws Exception {
083            producerCache.stop();
084        }
085    
086        protected void doStart() throws Exception {
087        }
088    }