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
027 import static org.apache.camel.util.ExchangeHelper.copyResultsPreservePattern;
028
029 /**
030 * A content enricher that enriches input data by first obtaining additional
031 * data from a <i>resource</i> represented by an endpoint <code>producer</code>
032 * and second by aggregating input data and additional data. Aggregation of
033 * input data and additional data is delegated to an {@link AggregationStrategy}
034 * object.
035 */
036 public class Enricher extends ServiceSupport implements Processor {
037
038 private AggregationStrategy aggregationStrategy;
039
040 private Producer producer;
041
042 /**
043 * Creates a new {@link Enricher}. The default aggregation strategy is to
044 * copy the additional data obtained from the enricher's resource over the
045 * input data. When using the copy aggregation strategy the enricher
046 * degenerates to a normal transformer.
047 *
048 * @param producer producer to resource endpoint.
049 */
050 public Enricher(Producer producer) {
051 this(defaultAggregationStrategy(), producer);
052 }
053
054 /**
055 * Creates a new {@link Enricher}.
056 *
057 * @param aggregationStrategy aggregation strategy to aggregate input data and additional data.
058 * @param producer producer to resource endpoint.
059 */
060 public Enricher(AggregationStrategy aggregationStrategy, Producer producer) {
061 this.aggregationStrategy = aggregationStrategy;
062 this.producer = producer;
063 }
064
065 /**
066 * Sets the aggregation strategy for this enricher.
067 *
068 * @param aggregationStrategy the aggregationStrategy to set
069 */
070 public void setAggregationStrategy(AggregationStrategy aggregationStrategy) {
071 this.aggregationStrategy = aggregationStrategy;
072 }
073
074 /**
075 * Sets the default aggregation strategy for this enricher.
076 */
077 public void setDefaultAggregationStrategy() {
078 this.aggregationStrategy = defaultAggregationStrategy();
079 }
080
081 /**
082 * Enriches the input data (<code>exchange</code>) by first obtaining
083 * additional data from an endpoint represented by an endpoint
084 * <code>producer</code> and second by aggregating input data and additional
085 * data. Aggregation of input data and additional data is delegated to an
086 * {@link AggregationStrategy} object set at construction time. If the
087 * message exchange with the resource endpoint fails then no aggregation
088 * will be done and the failed exchange content is copied over to the
089 * original message exchange.
090 *
091 * @param exchange input data.
092 */
093 public void process(Exchange exchange) throws Exception {
094 Exchange resourceExchange = createResourceExchange(exchange, ExchangePattern.InOut);
095 producer.process(resourceExchange);
096
097 if (resourceExchange.isFailed()) {
098 // copy resource exchange onto original exchange (preserving pattern)
099 copyResultsPreservePattern(exchange, resourceExchange);
100 } else {
101 prepareResult(exchange);
102 // aggregate original exchange and resource exchange
103 Exchange aggregatedExchange = aggregationStrategy.aggregate(exchange, resourceExchange);
104 // copy aggregation result onto original exchange (preserving pattern)
105 copyResultsPreservePattern(exchange, aggregatedExchange);
106 }
107 }
108
109 /**
110 * Creates a new {@link DefaultExchange} instance from the given
111 * <code>exchange</code>. The resulting exchange's pattern is defined by
112 * <code>pattern</code>.
113 *
114 * @param source exchange to copy from.
115 * @param pattern exchange pattern to set.
116 * @return created exchange.
117 */
118 protected Exchange createResourceExchange(Exchange source, ExchangePattern pattern) {
119 DefaultExchange target = new DefaultExchange(source.getContext());
120 target.copyFrom(source);
121 target.setPattern(pattern);
122 return target;
123 }
124
125 private static void prepareResult(Exchange exchange) {
126 if (exchange.getPattern().isOutCapable()) {
127 exchange.getOut().copyFrom(exchange.getIn());
128 }
129 }
130
131 private static AggregationStrategy defaultAggregationStrategy() {
132 return new CopyAggregationStrategy();
133 }
134
135 protected void doStart() throws Exception {
136 producer.start();
137 }
138
139 protected void doStop() throws Exception {
140 producer.stop();
141 }
142
143 private static class CopyAggregationStrategy implements AggregationStrategy {
144
145 public Exchange aggregate(Exchange oldExchange, Exchange newExchange) {
146 copyResultsPreservePattern(oldExchange, newExchange);
147 return oldExchange;
148 }
149
150 }
151
152 }