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    }