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.Processor;
022 import org.apache.camel.Producer;
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
030 import static org.apache.camel.util.ExchangeHelper.copyResultsPreservePattern;
031
032 /**
033 * A content enricher that enriches input data by first obtaining additional
034 * data from a <i>resource</i> represented by an endpoint <code>producer</code>
035 * and second by aggregating input data and additional data. Aggregation of
036 * input data and additional data is delegated to an {@link AggregationStrategy}
037 * object.
038 * <p/>
039 * Uses a {@link org.apache.camel.Producer} to obatin the additional data as opposed to {@link PollEnricher}
040 * that uses a {@link org.apache.camel.PollingConsumer}.
041 *
042 * @see PollEnricher
043 */
044 public class Enricher extends ServiceSupport implements Processor {
045
046 private static final transient Log LOG = LogFactory.getLog(Enricher.class);
047 private AggregationStrategy aggregationStrategy;
048 private Producer producer;
049
050 /**
051 * Creates a new {@link Enricher}. 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 producer producer to resource endpoint.
057 */
058 public Enricher(Producer producer) {
059 this(defaultAggregationStrategy(), producer);
060 }
061
062 /**
063 * Creates a new {@link Enricher}.
064 *
065 * @param aggregationStrategy aggregation strategy to aggregate input data and additional data.
066 * @param producer producer to resource endpoint.
067 */
068 public Enricher(AggregationStrategy aggregationStrategy, Producer producer) {
069 this.aggregationStrategy = aggregationStrategy;
070 this.producer = producer;
071 }
072
073 /**
074 * Sets the aggregation strategy for this 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 enricher.
084 */
085 public void setDefaultAggregationStrategy() {
086 this.aggregationStrategy = defaultAggregationStrategy();
087 }
088
089 /**
090 * Enriches the input data (<code>exchange</code>) by first obtaining
091 * additional data from an endpoint represented by an endpoint
092 * <code>producer</code> and second by aggregating input data and additional
093 * data. Aggregation of input data and additional data is delegated to an
094 * {@link AggregationStrategy} object set at construction time. If the
095 * message exchange with the resource endpoint fails then no aggregation
096 * will be done and the failed exchange content is copied over to the
097 * original message exchange.
098 *
099 * @param exchange input data.
100 */
101 public void process(Exchange exchange) throws Exception {
102 Exchange resourceExchange = createResourceExchange(exchange, ExchangePattern.InOut);
103 producer.process(resourceExchange);
104
105 if (resourceExchange.isFailed()) {
106 // copy resource exchange onto original exchange (preserving pattern)
107 copyResultsPreservePattern(exchange, resourceExchange);
108 } else {
109 prepareResult(exchange);
110
111 // aggregate original exchange and resource exchange
112 // but do not aggregate if the resource exchange was filtered
113 Boolean filtered = resourceExchange.getProperty(Exchange.FILTERED, Boolean.class);
114 if (filtered == null || !filtered) {
115 // prepare the exchanges for aggregation
116 ExchangeHelper.prepareAggregation(exchange, resourceExchange);
117 Exchange aggregatedExchange = aggregationStrategy.aggregate(exchange, resourceExchange);
118 // copy aggregation result onto original exchange (preserving pattern)
119 copyResultsPreservePattern(exchange, aggregatedExchange);
120 } else {
121 if (LOG.isTraceEnabled()) {
122 LOG.trace("Cannot aggregate exchange as its filtered: " + resourceExchange);
123 }
124 }
125 }
126 }
127
128 /**
129 * Creates a new {@link DefaultExchange} instance from the given
130 * <code>exchange</code>. The resulting exchange's pattern is defined by
131 * <code>pattern</code>.
132 *
133 * @param source exchange to copy from.
134 * @param pattern exchange pattern to set.
135 * @return created exchange.
136 */
137 protected Exchange createResourceExchange(Exchange source, ExchangePattern pattern) {
138 Exchange target = source.copy();
139 target.setPattern(pattern);
140 return target;
141 }
142
143 private static void prepareResult(Exchange exchange) {
144 if (exchange.getPattern().isOutCapable()) {
145 exchange.getOut().copyFrom(exchange.getIn());
146 }
147 }
148
149 private static AggregationStrategy defaultAggregationStrategy() {
150 return new CopyAggregationStrategy();
151 }
152
153 @Override
154 public String toString() {
155 return "Enrich[" + producer.getEndpoint().getEndpointUri() + "]";
156 }
157
158 protected void doStart() throws Exception {
159 producer.start();
160 }
161
162 protected void doStop() throws Exception {
163 producer.stop();
164 }
165
166 private static class CopyAggregationStrategy implements AggregationStrategy {
167
168 public Exchange aggregate(Exchange oldExchange, Exchange newExchange) {
169 copyResultsPreservePattern(oldExchange, newExchange);
170 return oldExchange;
171 }
172
173 }
174
175 }