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.Collection; 021 import java.util.Iterator; 022 import java.util.LinkedHashMap; 023 import java.util.Map; 024 025 import org.apache.camel.Exchange; 026 import org.apache.camel.Expression; 027 import org.apache.commons.logging.Log; 028 import org.apache.commons.logging.LogFactory; 029 030 /** 031 * A {@link Collection} which aggregates exchanges together using a correlation 032 * expression so that there is only a single message exchange sent for a single 033 * correlation key. 034 * 035 * @version $Revision: 36321 $ 036 */ 037 public class AggregationCollection extends AbstractCollection<Exchange> { 038 private static final transient Log LOG = LogFactory.getLog(AggregationCollection.class); 039 private final Expression<Exchange> correlationExpression; 040 private final AggregationStrategy aggregationStrategy; 041 private Map<Object, Exchange> map = new LinkedHashMap<Object, Exchange>(); 042 043 public AggregationCollection(Expression<Exchange> correlationExpression, 044 AggregationStrategy aggregationStrategy) { 045 this.correlationExpression = correlationExpression; 046 this.aggregationStrategy = aggregationStrategy; 047 } 048 049 protected Map<Object, Exchange> getMap() { 050 return map; 051 } 052 053 @Override 054 public boolean add(Exchange exchange) { 055 Object correlationKey = correlationExpression.evaluate(exchange); 056 Exchange oldExchange = map.get(correlationKey); 057 Exchange newExchange = exchange; 058 if (oldExchange != null) { 059 newExchange = aggregationStrategy.aggregate(oldExchange, newExchange); 060 } 061 062 // the strategy may just update the old exchange and return it 063 if (newExchange != oldExchange) { 064 LOG.debug("put exchange:" + newExchange + " for key:" + correlationKey); 065 map.put(correlationKey, newExchange); 066 } 067 onAggregation(correlationKey, newExchange); 068 return true; 069 } 070 071 public Iterator<Exchange> iterator() { 072 return map.values().iterator(); 073 } 074 075 public int size() { 076 return map.size(); 077 } 078 079 @Override 080 public void clear() { 081 map.clear(); 082 } 083 084 /** 085 * A strategy method allowing derived classes such as {@link PredicateAggregationCollection} 086 * to check to see if the aggregation has completed 087 */ 088 protected void onAggregation(Object correlationKey, Exchange newExchange) { 089 } 090 }