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.commons.logging.Log;
027 import org.apache.commons.logging.LogFactory;
028
029 import static org.apache.camel.util.ExchangeHelper.copyResultsPreservePattern;
030
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 */
038 public class Enricher extends ServiceSupport implements Processor {
039
040 private static final transient Log LOG = LogFactory.getLog(Enricher.class);
041 private AggregationStrategy aggregationStrategy;
042 private Producer producer;
043
044 /**
045 * Creates a new {@link Enricher}. The default aggregation strategy is to
046 * copy the additional data obtained from the enricher's resource over the
047 * input data. When using the copy aggregation strategy the enricher
048 * degenerates to a normal transformer.
049 *
050 * @param producer producer to resource endpoint.
051 */
052 public Enricher(Producer producer) {
053 this(defaultAggregationStrategy(), producer);
054 }
055
056 /**
057 * Creates a new {@link Enricher}.
058 *
059 * @param aggregationStrategy aggregation strategy to aggregate input data and additional data.
060 * @param producer producer to resource endpoint.
061 */
062 public Enricher(AggregationStrategy aggregationStrategy, Producer producer) {
063 this.aggregationStrategy = aggregationStrategy;
064 this.producer = producer;
065 }
066
067 /**
068 * Sets the aggregation strategy for this enricher.
069 *
070 * @param aggregationStrategy the aggregationStrategy to set
071 */
072 public void setAggregationStrategy(AggregationStrategy aggregationStrategy) {
073 this.aggregationStrategy = aggregationStrategy;
074 }
075
076 /**
077 * Sets the default aggregation strategy for this enricher.
078 */
079 public void setDefaultAggregationStrategy() {
080 this.aggregationStrategy = defaultAggregationStrategy();
081 }
082
083 /**
084 * Enriches the input data (<code>exchange</code>) by first obtaining
085 * additional data from an endpoint represented by an endpoint
086 * <code>producer</code> and second by aggregating input data and additional
087 * data. Aggregation of input data and additional data is delegated to an
088 * {@link AggregationStrategy} object set at construction time. If the
089 * message exchange with the resource endpoint fails then no aggregation
090 * will be done and the failed exchange content is copied over to the
091 * original message exchange.
092 *
093 * @param exchange input data.
094 */
095 public void process(Exchange exchange) throws Exception {
096 Exchange resourceExchange = createResourceExchange(exchange, ExchangePattern.InOut);
097 producer.process(resourceExchange);
098
099 if (resourceExchange.isFailed()) {
100 // copy resource exchange onto original exchange (preserving pattern)
101 copyResultsPreservePattern(exchange, resourceExchange);
102 } else {
103 prepareResult(exchange);
104
105 // aggregate original exchange and resource exchange
106 // but do not aggregate if the resource exchange was filtered
107 Boolean filtered = resourceExchange.getProperty(Exchange.FILTERED, Boolean.class);
108 if (filtered == null || !filtered) {
109 Exchange aggregatedExchange = aggregationStrategy.aggregate(exchange, resourceExchange);
110 // copy aggregation result onto original exchange (preserving pattern)
111 copyResultsPreservePattern(exchange, aggregatedExchange);
112 } else {
113 if (LOG.isTraceEnabled()) {
114 LOG.trace("Cannot aggregate exchange as its filtered: " + resourceExchange);
115 }
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 DefaultExchange target = new DefaultExchange(source.getContext());
131 target.copyFrom(source);
132 target.setPattern(pattern);
133 return target;
134 }
135
136 private static void prepareResult(Exchange exchange) {
137 if (exchange.getPattern().isOutCapable()) {
138 exchange.getOut().copyFrom(exchange.getIn());
139 }
140 }
141
142 private static AggregationStrategy defaultAggregationStrategy() {
143 return new CopyAggregationStrategy();
144 }
145
146 protected void doStart() throws Exception {
147 producer.start();
148 }
149
150 protected void doStop() throws Exception {
151 producer.stop();
152 }
153
154 private static class CopyAggregationStrategy implements AggregationStrategy {
155
156 public Exchange aggregate(Exchange oldExchange, Exchange newExchange) {
157 copyResultsPreservePattern(oldExchange, newExchange);
158 return oldExchange;
159 }
160
161 }
162
163 }