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
023 /**
024 * A <a href="http://camel.apache.org/delayer.html">Delayer</a> which
025 * delays processing the exchange until the correct amount of time has elapsed
026 * using an expression to determine the delivery time. <p/> For example if you
027 * wish to delay JMS messages by 25 seconds from their publish time you could
028 * create an instance of this class with the expression
029 * <code>header("JMSTimestamp")</code> and a delay value of 25000L.
030 *
031 * @version $Revision: 747062 $
032 */
033 public class Delayer extends DelayProcessorSupport {
034 private Expression timeExpression;
035 private long delay;
036
037 public Delayer(Processor processor, Expression timeExpression, long delay) {
038 super(processor);
039 this.timeExpression = timeExpression;
040 this.delay = delay;
041 }
042
043 @Override
044 public String toString() {
045 return "Delayer[on: " + timeExpression + " delay: " + delay + " to: " + getProcessor() + "]";
046 }
047
048 // Properties
049 // -------------------------------------------------------------------------
050 public long getDelay() {
051 return delay;
052 }
053
054 /**
055 * Sets the delay from the publish time; which is typically the time from
056 * the expression or the current system time if none is available
057 */
058 public void setDelay(long delay) {
059 this.delay = delay;
060 }
061
062 // Implementation methods
063 // -------------------------------------------------------------------------
064
065 /**
066 * Waits for an optional time period before continuing to process the
067 * exchange
068 */
069 protected void delay(Exchange exchange) throws Exception {
070 long time = 0;
071 if (timeExpression != null) {
072 Long longValue = timeExpression.evaluate(exchange, Long.class);
073 if (longValue != null) {
074 time = longValue;
075 }
076 }
077 if (time <= 0) {
078 time = defaultProcessTime(exchange);
079 }
080
081 time += delay;
082
083 waitUntil(time, exchange);
084 }
085
086 /**
087 * A Strategy Method to allow derived implementations to decide the current
088 * system time or some other default exchange property
089 */
090 protected long defaultProcessTime(Exchange exchange) {
091 return currentSystemTime();
092 }
093
094 }