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 * 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 AggregationStrategy}
036 * object.
037 * <p/>
038 * Uses a {@link org.apache.camel.Producer} to obtain the additional data as opposed to {@link PollEnricher}
039 * that uses a {@link org.apache.camel.PollingConsumer}.
040 *
041 * @see PollEnricher
042 */
043 public class Enricher extends ServiceSupport implements Processor {
044
045 private static final transient Log LOG = LogFactory.getLog(Enricher.class);
046 private AggregationStrategy aggregationStrategy;
047 private Producer producer;
048
049 /**
050 * Creates a new {@link Enricher}. 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 producer producer to resource endpoint.
056 */
057 public Enricher(Producer producer) {
058 this(defaultAggregationStrategy(), producer);
059 }
060
061 /**
062 * Creates a new {@link Enricher}.
063 *
064 * @param aggregationStrategy aggregation strategy to aggregate input data and additional data.
065 * @param producer producer to resource endpoint.
066 */
067 public Enricher(AggregationStrategy aggregationStrategy, Producer producer) {
068 this.aggregationStrategy = aggregationStrategy;
069 this.producer = producer;
070 }
071
072 /**
073 * Sets the aggregation strategy for this enricher.
074 *
075 * @param aggregationStrategy the aggregationStrategy to set
076 */
077 public void setAggregationStrategy(AggregationStrategy aggregationStrategy) {
078 this.aggregationStrategy = aggregationStrategy;
079 }
080
081 /**
082 * Sets the default aggregation strategy for this enricher.
083 */
084 public void setDefaultAggregationStrategy() {
085 this.aggregationStrategy = defaultAggregationStrategy();
086 }
087
088 /**
089 * Enriches the input data (<code>exchange</code>) by first obtaining
090 * additional data from an endpoint represented by an endpoint
091 * <code>producer</code> and second by aggregating input data and additional
092 * data. Aggregation of input data and additional data is delegated to an
093 * {@link AggregationStrategy} object set at construction time. If the
094 * message exchange with the resource endpoint fails then no aggregation
095 * will be done and the failed exchange content is copied over to the
096 * original message exchange.
097 *
098 * @param exchange input data.
099 */
100 public void process(Exchange exchange) throws Exception {
101 Exchange resourceExchange = createResourceExchange(exchange, ExchangePattern.InOut);
102 producer.process(resourceExchange);
103
104 if (resourceExchange.isFailed()) {
105 // copy resource exchange onto original exchange (preserving pattern)
106 copyResultsPreservePattern(exchange, resourceExchange);
107 } else {
108 prepareResult(exchange);
109
110 // prepare the exchanges for aggregation
111 ExchangeHelper.prepareAggregation(exchange, resourceExchange);
112 Exchange aggregatedExchange = aggregationStrategy.aggregate(exchange, resourceExchange);
113 if (aggregatedExchange != null) {
114 // copy aggregation result onto original exchange (preserving pattern)
115 copyResultsPreservePattern(exchange, aggregatedExchange);
116 }
117 }
118 }
119
120 /**
121 * Creates a new {@link DefaultExchange} instance from the given
122 * <code>exchange</code>. The resulting exchange's pattern is defined by
123 * <code>pattern</code>.
124 *
125 * @param source exchange to copy from.
126 * @param pattern exchange pattern to set.
127 * @return created exchange.
128 */
129 protected Exchange createResourceExchange(Exchange source, ExchangePattern pattern) {
130 Exchange target = source.copy();
131 target.setPattern(pattern);
132 return target;
133 }
134
135 private static void prepareResult(Exchange exchange) {
136 if (exchange.getPattern().isOutCapable()) {
137 exchange.getOut().copyFrom(exchange.getIn());
138 }
139 }
140
141 private static AggregationStrategy defaultAggregationStrategy() {
142 return new CopyAggregationStrategy();
143 }
144
145 @Override
146 public String toString() {
147 return "Enrich[" + producer.getEndpoint().getEndpointUri() + "]";
148 }
149
150 protected void doStart() throws Exception {
151 producer.start();
152 }
153
154 protected void doStop() throws Exception {
155 producer.stop();
156 }
157
158 private static class CopyAggregationStrategy implements AggregationStrategy {
159
160 public Exchange aggregate(Exchange oldExchange, Exchange newExchange) {
161 if (newExchange != null) {
162 copyResultsPreservePattern(oldExchange, newExchange);
163 }
164 return oldExchange;
165 }
166
167 }
168
169 }