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 */
017package org.apache.camel.processor;
018
019import java.util.concurrent.ScheduledExecutorService;
020
021import org.apache.camel.CamelContext;
022import org.apache.camel.Exchange;
023import org.apache.camel.Predicate;
024import org.apache.camel.Processor;
025import org.apache.camel.builder.ExpressionBuilder;
026import org.apache.camel.processor.exceptionpolicy.ExceptionPolicyStrategy;
027import org.apache.camel.util.CamelLogger;
028import 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 */
038public 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 deadLetterHandleException whether dead letter channel should handle (and ignore) exceptions which may be thrown during sending the message to the dead letter endpoint
052     * @param useOriginalBodyPolicy     should the original IN body be moved to the dead letter queue or the current exchange IN body?
053     * @param retryWhile                retry while
054     * @param executorService           the {@link java.util.concurrent.ScheduledExecutorService} to be used for redelivery thread pool. Can be <tt>null</tt>.
055     */
056    public DeadLetterChannel(CamelContext camelContext, Processor output, CamelLogger logger, Processor redeliveryProcessor, RedeliveryPolicy redeliveryPolicy,
057            ExceptionPolicyStrategy exceptionPolicyStrategy, Processor deadLetter, String deadLetterUri, boolean deadLetterHandleException,
058            boolean useOriginalBodyPolicy, Predicate retryWhile, ScheduledExecutorService executorService) {
059
060        super(camelContext, output, logger, redeliveryProcessor, redeliveryPolicy, deadLetter, deadLetterUri, deadLetterHandleException,
061                useOriginalBodyPolicy, retryWhile, executorService);
062        setExceptionPolicy(exceptionPolicyStrategy);
063    }
064
065    public void process(Exchange exchange) throws Exception {
066        // just to let the stack trace reveal that this is a dead letter channel
067        super.process(exchange);
068    }
069
070    @Override
071    public String toString() {
072        if (output == null) {
073            // if no output then don't do any description
074            return "";
075        }
076        return "DeadLetterChannel[" + output + ", " + (deadLetterUri != null ? deadLetterUri : deadLetter) + "]";
077    }
078
079    @Override
080    protected boolean isRunAllowedOnPreparingShutdown() {
081        // allow tu run as we want to move the message eto DLC, instead of rejecting the message
082        return true;
083    }
084
085    @Override
086    public boolean isDeadLetterChannel() {
087        return true;
088    }
089}