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.aggregate;
018
019import java.util.List;
020
021import org.apache.camel.Exchange;
022import org.apache.camel.Message;
023import org.apache.camel.impl.DefaultExchange;
024
025/**
026 * Aggregate all {@link Message} into a single combined Exchange holding all the
027 * aggregated messages in a {@link List} of {@link Message} as the message body.
028 * 
029 * This aggregation strategy can used in combination with {@link org.apache.camel.processor.Splitter} to batch messages
030 * 
031 * @version
032 */
033public class GroupedMessageAggregationStrategy extends AbstractListAggregationStrategy<Message> {
034
035    @Override
036    public Exchange aggregate(Exchange oldExchange, Exchange newExchange) {
037        if (oldExchange == null) {
038            // for the first time we must create a new empty exchange as the
039            // holder, as the outgoing exchange
040            // must not be one of the grouped exchanges, as that causes a
041            // endless circular reference
042            oldExchange = new DefaultExchange(newExchange);
043        }
044        return super.aggregate(oldExchange, newExchange);
045    }
046
047    @Override
048    public Message getValue(Exchange exchange) {
049        return exchange.getIn();
050    }
051}