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 }