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 java.util.concurrent.ScheduledExecutorService;
020
021 import org.apache.camel.CamelContext;
022 import org.apache.camel.Exchange;
023 import org.apache.camel.Predicate;
024 import org.apache.camel.Processor;
025 import org.apache.camel.builder.ExpressionBuilder;
026 import org.apache.camel.processor.exceptionpolicy.ExceptionPolicyStrategy;
027 import org.apache.camel.util.CamelLogger;
028 import org.apache.camel.util.ExpressionToPredicateAdapter;
029
030 /**
031 * Implements a <a
032 * href="http://camel.apache.org/dead-letter-channel.html">Dead Letter
033 * Channel</a> after attempting to redeliver the message using the
034 * {@link RedeliveryPolicy}
035 *
036 * @version
037 */
038 public class DeadLetterChannel extends RedeliveryErrorHandler {
039
040 /**
041 * Creates the dead letter channel.
042 *
043 * @param camelContext the camel context
044 * @param output outer processor that should use this dead letter channel
045 * @param logger logger to use for logging failures and redelivery attempts
046 * @param redeliveryProcessor an optional processor to run before redelivery attempt
047 * @param redeliveryPolicy policy for redelivery
048 * @param exceptionPolicyStrategy strategy for onException handling
049 * @param deadLetter the failure processor to send failed exchanges to
050 * @param deadLetterUri an optional uri for logging purpose
051 * @param useOriginalBodyPolicy should the original IN body be moved to the dead letter queue or the current exchange IN body?
052 * @param retryWhile retry while
053 * @param executorService the {@link java.util.concurrent.ScheduledExecutorService} to be used for redelivery thread pool. Can be <tt>null</tt>.
054 */
055 public DeadLetterChannel(CamelContext camelContext, Processor output, CamelLogger logger, Processor redeliveryProcessor, RedeliveryPolicy redeliveryPolicy,
056 ExceptionPolicyStrategy exceptionPolicyStrategy, Processor deadLetter, String deadLetterUri, boolean useOriginalBodyPolicy, Predicate retryWhile,
057 ScheduledExecutorService executorService) {
058
059 super(camelContext, output, logger, redeliveryProcessor, redeliveryPolicy, deadLetter, deadLetterUri, useOriginalBodyPolicy, retryWhile, executorService);
060 setExceptionPolicy(exceptionPolicyStrategy);
061 }
062
063 public void process(Exchange exchange) throws Exception {
064 // just to let the stack trace reveal that this is a dead letter channel
065 super.process(exchange);
066 }
067
068 @Override
069 public String toString() {
070 if (output == null) {
071 // if no output then don't do any description
072 return "";
073 }
074 return "DeadLetterChannel[" + output + ", " + (deadLetterUri != null ? deadLetterUri : deadLetter) + "]";
075 }
076
077 @Override
078 protected Predicate getDefaultHandledPredicate() {
079 // DeadLetterChannel handles errors before sending to DLQ
080 return ExpressionToPredicateAdapter.toPredicate(ExpressionBuilder.constantExpression(true));
081 }
082
083 @Override
084 protected boolean isRunAllowedOnPreparingShutdown() {
085 // allow tu run as we want to move the message eto DLC, instead of rejecting the message
086 return true;
087 }
088
089 @Override
090 public boolean isDeadLetterChannel() {
091 return true;
092 }
093 }