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.PollingConsumer;
021 import org.apache.camel.Processor;
022 import org.apache.camel.impl.EventDrivenPollingConsumer;
023 import org.apache.camel.impl.ServiceSupport;
024 import org.apache.camel.processor.aggregate.AggregationStrategy;
025 import org.apache.camel.util.ExchangeHelper;
026 import org.apache.commons.logging.Log;
027 import org.apache.commons.logging.LogFactory;
028 import static org.apache.camel.util.ExchangeHelper.copyResultsPreservePattern;
029
030 /**
031 * A content enricher that enriches input data by first obtaining additional
032 * data from a <i>resource</i> represented by an endpoint <code>producer</code>
033 * and second by aggregating input data and additional data. Aggregation of
034 * input data and additional data is delegated to an {@link org.apache.camel.processor.aggregate.AggregationStrategy}
035 * object.
036 * <p/>
037 * Uses a {@link org.apache.camel.PollingConsumer} to obtain the additional data as opposed to {@link Enricher}
038 * that uses a {@link org.apache.camel.Producer}.
039 *
040 * @see Enricher
041 */
042 public class PollEnricher extends ServiceSupport implements Processor {
043
044 private static final transient Log LOG = LogFactory.getLog(PollEnricher.class);
045 private AggregationStrategy aggregationStrategy;
046 private PollingConsumer consumer;
047 private long timeout;
048
049 /**
050 * Creates a new {@link PollEnricher}. The default aggregation strategy is to
051 * copy the additional data obtained from the enricher's resource over the
052 * input data. When using the copy aggregation strategy the enricher
053 * degenerates to a normal transformer.
054 *
055 * @param consumer consumer to resource endpoint.
056 */
057 public PollEnricher(PollingConsumer consumer) {
058 this(defaultAggregationStrategy(), consumer, 0);
059 }
060
061 /**
062 * Creates a new {@link PollEnricher}.
063 *
064 * @param aggregationStrategy aggregation strategy to aggregate input data and additional data.
065 * @param consumer consumer to resource endpoint.
066 */
067 public PollEnricher(AggregationStrategy aggregationStrategy, PollingConsumer consumer, long timeout) {
068 this.aggregationStrategy = aggregationStrategy;
069 this.consumer = consumer;
070 this.timeout = timeout;
071 }
072
073 /**
074 * Sets the aggregation strategy for this poll enricher.
075 *
076 * @param aggregationStrategy the aggregationStrategy to set
077 */
078 public void setAggregationStrategy(AggregationStrategy aggregationStrategy) {
079 this.aggregationStrategy = aggregationStrategy;
080 }
081
082 /**
083 * Sets the default aggregation strategy for this poll enricher.
084 */
085 public void setDefaultAggregationStrategy() {
086 this.aggregationStrategy = defaultAggregationStrategy();
087 }
088
089 /**
090 * Sets the timeout to use when polling.
091 * <p/>
092 * Use 0 or negative to not use timeout and block until data is available.
093 *
094 * @param timeout timeout in millis.
095 */
096 public void setTimeout(long timeout) {
097 this.timeout = timeout;
098 }
099
100 /**
101 * Enriches the input data (<code>exchange</code>) by first obtaining
102 * additional data from an endpoint represented by an endpoint
103 * <code>producer</code> and second by aggregating input data and additional
104 * data. Aggregation of input data and additional data is delegated to an
105 * {@link org.apache.camel.processor.aggregate.AggregationStrategy} object set at construction time. If the
106 * message exchange with the resource endpoint fails then no aggregation
107 * will be done and the failed exchange content is copied over to the
108 * original message exchange.
109 *
110 * @param exchange input data.
111 */
112 public void process(Exchange exchange) throws Exception {
113 preChceckPoll(exchange);
114
115 Exchange resourceExchange;
116 if (timeout < 0) {
117 if (LOG.isDebugEnabled()) {
118 LOG.debug("Consumer receive: " + consumer);
119 }
120 resourceExchange = consumer.receive();
121 } else if (timeout == 0) {
122 if (LOG.isDebugEnabled()) {
123 LOG.debug("Consumer receiveNoWait: " + consumer);
124 }
125 resourceExchange = consumer.receiveNoWait();
126 } else {
127 if (LOG.isDebugEnabled()) {
128 LOG.debug("Consumer receive with timeout: " + timeout + " ms. " + consumer);
129 }
130 resourceExchange = consumer.receive(timeout);
131 }
132
133 if (LOG.isDebugEnabled()) {
134 if (resourceExchange == null) {
135 LOG.debug("Consumer received no exchange");
136 } else {
137 LOG.debug("Consumer received: " + resourceExchange);
138 }
139 }
140
141 if (resourceExchange != null && resourceExchange.isFailed()) {
142 // copy resource exchange onto original exchange (preserving pattern)
143 copyResultsPreservePattern(exchange, resourceExchange);
144 } else {
145 prepareResult(exchange);
146
147 // prepare the exchanges for aggregation
148 ExchangeHelper.prepareAggregation(exchange, resourceExchange);
149 Exchange aggregatedExchange = aggregationStrategy.aggregate(exchange, resourceExchange);
150 if (aggregatedExchange != null) {
151 // copy aggregation result onto original exchange (preserving pattern)
152 copyResultsPreservePattern(exchange, aggregatedExchange);
153 }
154 }
155 }
156
157 /**
158 * Strategy to pre check polling.
159 * <p/>
160 * Is currently used to prevent doing poll enrich from a file based endpoint when the current route also
161 * started from a file based endpoint as that is not currently supported.
162 *
163 * @param exchange the current exchange
164 */
165 protected void preChceckPoll(Exchange exchange) throws Exception {
166 // cannot poll a file endpoint if already consuming from a file endpoint (CAMEL-1895)
167 if (consumer instanceof EventDrivenPollingConsumer) {
168 EventDrivenPollingConsumer edpc = (EventDrivenPollingConsumer) consumer;
169 boolean fileBasedConsumer = edpc.getEndpoint().getEndpointKey().startsWith("file") || edpc.getEndpoint().getEndpointKey().startsWith("ftp");
170 boolean fileBasedExchange = exchange.getFromEndpoint().getEndpointUri().startsWith("file") || exchange.getFromEndpoint().getEndpointUri().startsWith("ftp");
171 if (fileBasedConsumer && fileBasedExchange) {
172 throw new IllegalArgumentException("Camel currently does not support pollEnrich from a file/ftp endpoint"
173 + " when the route also started from a file/ftp endpoint."
174 + " Started from: " + exchange.getFromEndpoint().getEndpointUri() + " pollEnrich: " + edpc.getEndpoint().getEndpointUri());
175 }
176 }
177 }
178
179 private static void prepareResult(Exchange exchange) {
180 if (exchange.getPattern().isOutCapable()) {
181 exchange.getOut().copyFrom(exchange.getIn());
182 }
183 }
184
185 private static AggregationStrategy defaultAggregationStrategy() {
186 return new CopyAggregationStrategy();
187 }
188
189 @Override
190 public String toString() {
191 return "PollEnrich[" + consumer + "]";
192 }
193
194 protected void doStart() throws Exception {
195 consumer.start();
196 }
197
198 protected void doStop() throws Exception {
199 consumer.stop();
200 }
201
202 private static class CopyAggregationStrategy implements AggregationStrategy {
203
204 public Exchange aggregate(Exchange oldExchange, Exchange newExchange) {
205 if (newExchange != null) {
206 copyResultsPreservePattern(oldExchange, newExchange);
207 }
208 return oldExchange;
209 }
210
211 }
212
213 }