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.Expression;
021    import org.apache.camel.Processor;
022    import org.apache.camel.util.ExpressionHelper;
023    
024    /**
025     * A <a href="http://activemq.apache.org/camel/delayer.html">Delayer</a> which
026     * delays processing the exchange until the correct amount of time has elapsed
027     * using an expression to determine the delivery time. <p/> For example if you
028     * wish to delay JMS messages by 25 seconds from their publish time you could
029     * create an instance of this class with the expression
030     * <code>header("JMSTimestamp")</code> and a delay value of 25000L.
031     * 
032     * @version $Revision: 35332 $
033     */
034    public class Delayer extends DelayProcessorSupport {
035        private Expression<Exchange> timeExpression;
036        private long delay;
037    
038        public Delayer(Processor processor, Expression<Exchange> timeExpression, long delay) {
039            super(processor);
040            this.timeExpression = timeExpression;
041            this.delay = delay;
042        }
043    
044        @Override
045        public String toString() {
046            return "Delayer[on: " + timeExpression + " delay: " + delay + " to: " + getProcessor() + "]";
047        }
048    
049        // Properties
050        // -------------------------------------------------------------------------
051        public long getDelay() {
052            return delay;
053        }
054    
055        /**
056         * Sets the delay from the publish time; which is typically the time from
057         * the expression or the current system time if none is available
058         */
059        public void setDelay(long delay) {
060            this.delay = delay;
061        }
062    
063        // Implementation methods
064        // -------------------------------------------------------------------------
065    
066        /**
067         * Waits for an optional time period before continuing to process the
068         * exchange
069         */
070        protected void delay(Exchange exchange) throws Exception {
071            long time = 0;
072            if (timeExpression != null) {
073                Long longValue = ExpressionHelper.evaluateAsType(timeExpression, exchange, Long.class);
074                if (longValue != null) {
075                    time = longValue.longValue();
076                }
077            }
078            if (time <= 0) {
079                time = defaultProcessTime(exchange);
080            }
081    
082            time += delay;
083    
084            waitUntil(time, exchange);
085        }
086    
087        /**
088         * A Strategy Method to allow derived implementations to decide the current
089         * system time or some other default exchange property
090         * 
091         * @param exchange
092         */
093        protected long defaultProcessTime(Exchange exchange) {
094            return currentSystemTime();
095        }
096    
097    }