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 import org.apache.commons.logging.Log;
027 import org.apache.commons.logging.LogFactory;
028
029 /**
030 * A {@link java.util.Collection} which aggregates exchanges together using a correlation
031 * expression so that there is only a single message exchange sent for a single
032 * correlation key.
033 *
034 * @version $Revision: 752464 $
035 */
036 public class DefaultAggregationCollection extends AbstractCollection<Exchange> implements AggregationCollection {
037
038 private static final transient Log LOG = LogFactory.getLog(DefaultAggregationCollection.class);
039 private Expression correlationExpression;
040 private AggregationStrategy aggregationStrategy;
041 private final Map<Object, Exchange> aggregated = new LinkedHashMap<Object, Exchange>();
042
043 public DefaultAggregationCollection() {
044 }
045
046 public DefaultAggregationCollection(Expression correlationExpression, AggregationStrategy aggregationStrategy) {
047 this.correlationExpression = correlationExpression;
048 this.aggregationStrategy = aggregationStrategy;
049 }
050
051 protected Map<Object, Exchange> getAggregated() {
052 return aggregated;
053 }
054
055 @Override
056 public boolean add(Exchange exchange) {
057 Object correlationKey = correlationExpression.evaluate(exchange);
058 if (LOG.isDebugEnabled()) {
059 LOG.debug("Evaluated expression: " + correlationExpression + " as CorrelationKey: " + correlationKey);
060 }
061 Exchange oldExchange = aggregated.get(correlationKey);
062 Exchange newExchange = exchange;
063
064 if (oldExchange != null) {
065 Integer count = oldExchange.getProperty(Exchange.AGGREGATED_SIZE, Integer.class);
066 if (count == null) {
067 count = 1;
068 }
069 count++;
070 newExchange = aggregationStrategy.aggregate(oldExchange, newExchange);
071 newExchange.setProperty(Exchange.AGGREGATED_SIZE, count);
072 }
073
074 // the strategy may just update the old exchange and return it
075 if (!newExchange.equals(oldExchange)) {
076 if (LOG.isDebugEnabled()) {
077 LOG.debug("Put exchange:" + newExchange + " with coorelation key:" + correlationKey);
078 }
079 if (oldExchange == null) {
080 newExchange.setProperty(Exchange.AGGREGATED_SIZE, Integer.valueOf(1));
081 }
082 aggregated.put(correlationKey, newExchange);
083 }
084
085 onAggregation(correlationKey, newExchange);
086
087 return true;
088 }
089
090 public Iterator<Exchange> iterator() {
091 return aggregated.values().iterator();
092 }
093
094 public int size() {
095 return aggregated.size();
096 }
097
098 @Override
099 public void clear() {
100 aggregated.clear();
101 }
102
103 public void onAggregation(Object correlationKey, Exchange newExchange) {
104 }
105
106 public Expression getCorrelationExpression() {
107 return correlationExpression;
108 }
109
110 public void setCorrelationExpression(Expression correlationExpression) {
111 this.correlationExpression = correlationExpression;
112 }
113
114 public AggregationStrategy getAggregationStrategy() {
115 return aggregationStrategy;
116 }
117
118 public void setAggregationStrategy(AggregationStrategy aggregationStrategy) {
119 this.aggregationStrategy = aggregationStrategy;
120 }
121 }