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.Exchange; 020 import org.apache.camel.ExchangePattern; 021 import org.apache.camel.PollingConsumer; 022 import org.apache.camel.Processor; 023 import org.apache.camel.impl.DefaultExchange; 024 import org.apache.camel.impl.ServiceSupport; 025 import org.apache.camel.processor.aggregate.AggregationStrategy; 026 import org.apache.camel.util.ExchangeHelper; 027 import org.apache.commons.logging.Log; 028 import org.apache.commons.logging.LogFactory; 029 import static org.apache.camel.util.ExchangeHelper.copyResultsPreservePattern; 030 031 /** 032 * A content enricher that enriches input data by first obtaining additional 033 * data from a <i>resource</i> represented by an endpoint <code>producer</code> 034 * and second by aggregating input data and additional data. Aggregation of 035 * input data and additional data is delegated to an {@link org.apache.camel.processor.aggregate.AggregationStrategy} 036 * object. 037 * <p/> 038 * Uses a {@link org.apache.camel.PollingConsumer} to obatin the additional data as opposed to {@link Enricher} 039 * that uses a {@link org.apache.camel.Producer}. 040 * 041 * @see Enricher 042 */ 043 public class PollEnricher extends ServiceSupport implements Processor { 044 045 private static final transient Log LOG = LogFactory.getLog(PollEnricher.class); 046 private AggregationStrategy aggregationStrategy; 047 private PollingConsumer consumer; 048 private long timeout; 049 050 /** 051 * Creates a new {@link PollEnricher}. The default aggregation strategy is to 052 * copy the additional data obtained from the enricher's resource over the 053 * input data. When using the copy aggregation strategy the enricher 054 * degenerates to a normal transformer. 055 * 056 * @param consumer consumer to resource endpoint. 057 */ 058 public PollEnricher(PollingConsumer consumer) { 059 this(defaultAggregationStrategy(), consumer, 0); 060 } 061 062 /** 063 * Creates a new {@link PollEnricher}. 064 * 065 * @param aggregationStrategy aggregation strategy to aggregate input data and additional data. 066 * @param consumer consumer to resource endpoint. 067 */ 068 public PollEnricher(AggregationStrategy aggregationStrategy, PollingConsumer consumer, long timeout) { 069 this.aggregationStrategy = aggregationStrategy; 070 this.consumer = consumer; 071 this.timeout = timeout; 072 } 073 074 /** 075 * Sets the aggregation strategy for this poll enricher. 076 * 077 * @param aggregationStrategy the aggregationStrategy to set 078 */ 079 public void setAggregationStrategy(AggregationStrategy aggregationStrategy) { 080 this.aggregationStrategy = aggregationStrategy; 081 } 082 083 /** 084 * Sets the default aggregation strategy for this poll enricher. 085 */ 086 public void setDefaultAggregationStrategy() { 087 this.aggregationStrategy = defaultAggregationStrategy(); 088 } 089 090 /** 091 * Sets the timeout to use when polling. 092 * <p/> 093 * Use 0 or negative to not use timeout and block until data is available. 094 * 095 * @param timeout timeout in millis. 096 */ 097 public void setTimeout(long timeout) { 098 this.timeout = timeout; 099 } 100 101 /** 102 * Enriches the input data (<code>exchange</code>) by first obtaining 103 * additional data from an endpoint represented by an endpoint 104 * <code>producer</code> and second by aggregating input data and additional 105 * data. Aggregation of input data and additional data is delegated to an 106 * {@link org.apache.camel.processor.aggregate.AggregationStrategy} object set at construction time. If the 107 * message exchange with the resource endpoint fails then no aggregation 108 * will be done and the failed exchange content is copied over to the 109 * original message exchange. 110 * 111 * @param exchange input data. 112 */ 113 public void process(Exchange exchange) throws Exception { 114 Exchange resourceExchange; 115 if (timeout < 0) { 116 if (LOG.isDebugEnabled()) { 117 LOG.debug("Consumer receive: " + consumer); 118 } 119 resourceExchange = consumer.receive(); 120 } else if (timeout == 0) { 121 if (LOG.isDebugEnabled()) { 122 LOG.debug("Consumer receiveNoWait: " + consumer); 123 } 124 resourceExchange = consumer.receiveNoWait(); 125 } else { 126 if (LOG.isDebugEnabled()) { 127 LOG.debug("Consumer receive with timeout: " + timeout + " ms. " + consumer); 128 } 129 resourceExchange = consumer.receive(timeout); 130 } 131 132 if (resourceExchange != null && resourceExchange.isFailed()) { 133 // copy resource exchange onto original exchange (preserving pattern) 134 copyResultsPreservePattern(exchange, resourceExchange); 135 } else { 136 prepareResult(exchange); 137 138 // aggregate original exchange and resource exchange 139 // but do not aggregate if the resource exchange was filtered 140 Boolean filtered = null; 141 if (resourceExchange != null) { 142 filtered = resourceExchange.getProperty(Exchange.FILTERED, Boolean.class); 143 } 144 if (filtered == null || !filtered) { 145 // prepare the exchanges for aggregation 146 ExchangeHelper.prepareAggregation(exchange, resourceExchange); 147 Exchange aggregatedExchange = aggregationStrategy.aggregate(exchange, resourceExchange); 148 // copy aggregation result onto original exchange (preserving pattern) 149 copyResultsPreservePattern(exchange, aggregatedExchange); 150 } else { 151 if (LOG.isTraceEnabled()) { 152 LOG.trace("Cannot aggregate exchange as its filtered: " + resourceExchange); 153 } 154 } 155 } 156 } 157 158 /** 159 * Creates a new {@link org.apache.camel.impl.DefaultExchange} instance from the given 160 * <code>exchange</code>. The resulting exchange's pattern is defined by 161 * <code>pattern</code>. 162 * 163 * @param source exchange to copy from. 164 * @param pattern exchange pattern to set. 165 * @return created exchange. 166 */ 167 protected Exchange createResourceExchange(Exchange source, ExchangePattern pattern) { 168 Exchange target = source.copy(); 169 target.setPattern(pattern); 170 return target; 171 } 172 173 private static void prepareResult(Exchange exchange) { 174 if (exchange.getPattern().isOutCapable()) { 175 exchange.getOut().copyFrom(exchange.getIn()); 176 } 177 } 178 179 private static AggregationStrategy defaultAggregationStrategy() { 180 return new CopyAggregationStrategy(); 181 } 182 183 @Override 184 public String toString() { 185 return "PollEnrich[" + consumer + "]"; 186 } 187 188 protected void doStart() throws Exception { 189 consumer.start(); 190 } 191 192 protected void doStop() throws Exception { 193 consumer.stop(); 194 } 195 196 private static class CopyAggregationStrategy implements AggregationStrategy { 197 198 public Exchange aggregate(Exchange oldExchange, Exchange newExchange) { 199 copyResultsPreservePattern(oldExchange, newExchange); 200 return oldExchange; 201 } 202 203 } 204 205 }