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 org.apache.camel.Endpoint; 020 import org.apache.camel.Expression; 021 import org.apache.camel.Processor; 022 import org.apache.camel.processor.aggregate.AggregationCollection; 023 import org.apache.camel.processor.aggregate.AggregationStrategy; 024 025 /** 026 * An implementation of the <a 027 * href="http://activemq.apache.org/camel/aggregator.html">Aggregator</a> 028 * pattern where a batch of messages are processed (up to a maximum amount or 029 * until some timeout is reached) and messages for the same correlation key are 030 * combined together using some kind of 031 * {@link AggregationStrategy ) (by default the latest message is used) to compress 032 * many message exchanges * into a smaller number of exchanges. <p/> A good 033 * example of this is stock market data; you may be receiving 30,000 034 * messages/second and you may want to throttle it right down so that multiple 035 * messages for the same stock are combined (or just the latest message is used 036 * and older prices are discarded). Another idea is to combine line item 037 * messages together into a single invoice message. 038 * 039 * @version $Revision: 1.1 $ 040 * @param correlationExpression the expression used to calculate the correlation 041 * key. For a JMS message this could be the expression 042 * <code>header("JMSDestination")</code> or 043 * <code>header("JMSCorrelationID")</code> 044 */ 045 public class Aggregator extends BatchProcessor { 046 public Aggregator(Endpoint endpoint, Processor processor, Expression correlationExpression, 047 AggregationStrategy aggregationStrategy) { 048 this(endpoint, processor, new AggregationCollection(correlationExpression, aggregationStrategy)); 049 } 050 051 public Aggregator(Endpoint endpoint, Processor processor, AggregationCollection collection) { 052 super(endpoint, processor, collection); 053 } 054 055 @Override 056 public String toString() { 057 return "Aggregator[to: " + getProcessor() + "]"; 058 } 059 }