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.aggregate;
018
019 import java.util.AbstractCollection;
020 import java.util.Iterator;
021 import java.util.LinkedHashMap;
022 import java.util.Map;
023
024 import org.apache.camel.Exchange;
025 import org.apache.camel.Expression;
026
027 /**
028 * A {@link Collection} which aggregates exchanges together using a correlation
029 * expression so that there is only a single message exchange sent for a single
030 * correlation key.
031 *
032 * @version $Revision: 1.1 $
033 */
034 public class AggregationCollection extends AbstractCollection<Exchange> {
035 private final Expression<Exchange> correlationExpression;
036 private final AggregationStrategy aggregationStrategy;
037 private Map<Object, Exchange> map = new LinkedHashMap<Object, Exchange>();
038
039 public AggregationCollection(Expression<Exchange> correlationExpression,
040 AggregationStrategy aggregationStrategy) {
041 this.correlationExpression = correlationExpression;
042 this.aggregationStrategy = aggregationStrategy;
043 }
044
045 @Override
046 public boolean add(Exchange exchange) {
047 Object correlationKey = correlationExpression.evaluate(exchange);
048 Exchange oldExchange = map.get(correlationKey);
049 Exchange newExchange = exchange;
050 if (oldExchange != null) {
051 newExchange = aggregationStrategy.aggregate(oldExchange, newExchange);
052 }
053
054 // the strategy may just update the old exchange and return it
055 if (newExchange != oldExchange) {
056 map.put(correlationKey, newExchange);
057 }
058 return true;
059 }
060
061 public Iterator<Exchange> iterator() {
062 return map.values().iterator();
063 }
064
065 public int size() {
066 return map.size();
067 }
068 }