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.AsyncCallback;
020 import org.apache.camel.AsyncProcessor;
021 import org.apache.camel.CamelExchangeException;
022 import org.apache.camel.Exchange;
023 import org.apache.camel.PollingConsumer;
024 import org.apache.camel.processor.aggregate.AggregationStrategy;
025 import org.apache.camel.support.ServiceSupport;
026 import org.apache.camel.util.AsyncProcessorHelper;
027 import org.apache.camel.util.ExchangeHelper;
028 import org.apache.camel.util.ServiceHelper;
029 import org.slf4j.Logger;
030 import org.slf4j.LoggerFactory;
031
032 import static org.apache.camel.util.ExchangeHelper.copyResultsPreservePattern;
033
034 /**
035 * A content enricher that enriches input data by first obtaining additional
036 * data from a <i>resource</i> represented by an endpoint <code>producer</code>
037 * and second by aggregating input data and additional data. Aggregation of
038 * input data and additional data is delegated to an {@link org.apache.camel.processor.aggregate.AggregationStrategy}
039 * object.
040 * <p/>
041 * Uses a {@link org.apache.camel.PollingConsumer} to obtain the additional data as opposed to {@link Enricher}
042 * that uses a {@link org.apache.camel.Producer}.
043 *
044 * @see Enricher
045 */
046 public class PollEnricher extends ServiceSupport implements AsyncProcessor {
047
048 private static final Logger LOG = LoggerFactory.getLogger(PollEnricher.class);
049 private AggregationStrategy aggregationStrategy;
050 private PollingConsumer consumer;
051 private long timeout;
052
053 /**
054 * Creates a new {@link PollEnricher}. The default aggregation strategy is to
055 * copy the additional data obtained from the enricher's resource over the
056 * input data. When using the copy aggregation strategy the enricher
057 * degenerates to a normal transformer.
058 *
059 * @param consumer consumer to resource endpoint.
060 */
061 public PollEnricher(PollingConsumer consumer) {
062 this(defaultAggregationStrategy(), consumer, 0);
063 }
064
065 /**
066 * Creates a new {@link PollEnricher}.
067 *
068 * @param aggregationStrategy aggregation strategy to aggregate input data and additional data.
069 * @param consumer consumer to resource endpoint.
070 * @param timeout timeout in millis
071 */
072 public PollEnricher(AggregationStrategy aggregationStrategy, PollingConsumer consumer, long timeout) {
073 this.aggregationStrategy = aggregationStrategy;
074 this.consumer = consumer;
075 this.timeout = timeout;
076 }
077
078 /**
079 * Sets the aggregation strategy for this poll enricher.
080 *
081 * @param aggregationStrategy the aggregationStrategy to set
082 */
083 public void setAggregationStrategy(AggregationStrategy aggregationStrategy) {
084 this.aggregationStrategy = aggregationStrategy;
085 }
086
087 /**
088 * Sets the default aggregation strategy for this poll enricher.
089 */
090 public void setDefaultAggregationStrategy() {
091 this.aggregationStrategy = defaultAggregationStrategy();
092 }
093
094 /**
095 * Sets the timeout to use when polling.
096 * <p/>
097 * Use 0 to use receiveNoWait,
098 * Use -1 to use receive with no timeout (which will block until data is available).
099 *
100 * @param timeout timeout in millis.
101 */
102 public void setTimeout(long timeout) {
103 this.timeout = timeout;
104 }
105
106 public void process(Exchange exchange) throws Exception {
107 AsyncProcessorHelper.process(this, exchange);
108 }
109
110 /**
111 * Enriches the input data (<code>exchange</code>) by first obtaining
112 * additional data from an endpoint represented by an endpoint
113 * <code>producer</code> and second by aggregating input data and additional
114 * data. Aggregation of input data and additional data is delegated to an
115 * {@link org.apache.camel.processor.aggregate.AggregationStrategy} object set at construction time. If the
116 * message exchange with the resource endpoint fails then no aggregation
117 * will be done and the failed exchange content is copied over to the
118 * original message exchange.
119 *
120 * @param exchange input data.
121 */
122 @Override
123 public boolean process(Exchange exchange, AsyncCallback callback) {
124 try {
125 preCheckPoll(exchange);
126 } catch (Exception e) {
127 exchange.setException(new CamelExchangeException("Error during pre poll check", exchange, e));
128 callback.done(true);
129 return true;
130 }
131
132 Exchange resourceExchange;
133 if (timeout < 0) {
134 LOG.debug("Consumer receive: {}", consumer);
135 resourceExchange = consumer.receive();
136 } else if (timeout == 0) {
137 LOG.debug("Consumer receiveNoWait: {}", consumer);
138 resourceExchange = consumer.receiveNoWait();
139 } else {
140 LOG.debug("Consumer receive with timeout: {} ms. {}", timeout, consumer);
141 resourceExchange = consumer.receive(timeout);
142 }
143
144 if (resourceExchange == null) {
145 LOG.debug("Consumer received no exchange");
146 } else {
147 LOG.debug("Consumer received: {}", resourceExchange);
148 }
149
150 if (resourceExchange != null && resourceExchange.isFailed()) {
151 // copy resource exchange onto original exchange (preserving pattern)
152 copyResultsPreservePattern(exchange, resourceExchange);
153 } else {
154 prepareResult(exchange);
155
156 try {
157 // prepare the exchanges for aggregation
158 ExchangeHelper.prepareAggregation(exchange, resourceExchange);
159 // must catch any exception from aggregation
160 Exchange aggregatedExchange = aggregationStrategy.aggregate(exchange, resourceExchange);
161 if (aggregatedExchange != null) {
162 // copy aggregation result onto original exchange (preserving pattern)
163 copyResultsPreservePattern(exchange, aggregatedExchange);
164 // handover any synchronization
165 if (resourceExchange != null) {
166 resourceExchange.handoverCompletions(exchange);
167 }
168 }
169 } catch (Throwable e) {
170 exchange.setException(new CamelExchangeException("Error occurred during aggregation", exchange, e));
171 callback.done(true);
172 return true;
173 }
174 }
175
176 // set header with the uri of the endpoint enriched so we can use that for tracing etc
177 if (exchange.hasOut()) {
178 exchange.getOut().setHeader(Exchange.TO_ENDPOINT, consumer.getEndpoint().getEndpointUri());
179 } else {
180 exchange.getIn().setHeader(Exchange.TO_ENDPOINT, consumer.getEndpoint().getEndpointUri());
181 }
182
183 callback.done(true);
184 return true;
185 }
186
187 /**
188 * Strategy to pre check polling.
189 * <p/>
190 * Is currently used to prevent doing poll enrich from a file based endpoint when the current route also
191 * started from a file based endpoint as that is not currently supported.
192 *
193 * @param exchange the current exchange
194 */
195 protected void preCheckPoll(Exchange exchange) throws Exception {
196 // noop
197 }
198
199 private static void prepareResult(Exchange exchange) {
200 if (exchange.getPattern().isOutCapable()) {
201 exchange.getOut().copyFrom(exchange.getIn());
202 }
203 }
204
205 private static AggregationStrategy defaultAggregationStrategy() {
206 return new CopyAggregationStrategy();
207 }
208
209 @Override
210 public String toString() {
211 return "PollEnrich[" + consumer + "]";
212 }
213
214 protected void doStart() throws Exception {
215 ServiceHelper.startServices(aggregationStrategy, consumer);
216 }
217
218 protected void doStop() throws Exception {
219 ServiceHelper.stopServices(consumer, aggregationStrategy);
220 }
221
222 private static class CopyAggregationStrategy implements AggregationStrategy {
223
224 public Exchange aggregate(Exchange oldExchange, Exchange newExchange) {
225 if (newExchange != null) {
226 copyResultsPreservePattern(oldExchange, newExchange);
227 } else {
228 // if no newExchange then there was no message from the external resource
229 // and therefore we should set an empty body to indicate this fact
230 // but keep headers/attachments as we want to propagate those
231 oldExchange.getIn().setBody(null);
232 oldExchange.setOut(null);
233 }
234 return oldExchange;
235 }
236
237 }
238
239 }