| /** |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.camel.processor.idempotent; |
| |
| import java.util.ArrayList; |
| import java.util.List; |
| |
| import org.apache.camel.Exchange; |
| import org.apache.camel.Expression; |
| import org.apache.camel.Navigate; |
| import org.apache.camel.Processor; |
| import org.apache.camel.impl.ServiceSupport; |
| import org.apache.camel.spi.IdempotentRepository; |
| import org.apache.camel.util.ServiceHelper; |
| import org.apache.commons.logging.Log; |
| import org.apache.commons.logging.LogFactory; |
| |
| /** |
| * An implementation of the <a |
| * href="http://camel.apache.org/idempotent-consumer.html">Idempotent Consumer</a> pattern. |
| * |
| * @version $Revision$ |
| */ |
| public class IdempotentConsumer extends ServiceSupport implements Processor, Navigate<Processor> { |
| private static final transient Log LOG = LogFactory.getLog(IdempotentConsumer.class); |
| private final Expression messageIdExpression; |
| private final Processor processor; |
| private final IdempotentRepository<String> idempotentRepository; |
| private final boolean eager; |
| |
| public IdempotentConsumer(Expression messageIdExpression, |
| IdempotentRepository<String> idempotentRepository, boolean eager, Processor processor) { |
| this.messageIdExpression = messageIdExpression; |
| this.idempotentRepository = idempotentRepository; |
| this.eager = eager; |
| this.processor = processor; |
| } |
| |
| @Override |
| public String toString() { |
| return "IdempotentConsumer[" + messageIdExpression + " -> " + processor + "]"; |
| } |
| |
| public void process(Exchange exchange) throws Exception { |
| final String messageId = messageIdExpression.evaluate(exchange, String.class); |
| if (messageId == null) { |
| throw new NoMessageIdException(exchange, messageIdExpression); |
| } |
| |
| boolean newKey; |
| if (eager) { |
| // add the key to the repository |
| newKey = idempotentRepository.add(messageId); |
| } else { |
| // check if we alrady have the key |
| newKey = !idempotentRepository.contains(messageId); |
| } |
| |
| if (!newKey) { |
| // we already have this key so its a duplicate message |
| onDuplicateMessage(exchange, messageId); |
| return; |
| } |
| |
| // register our on completion callback |
| exchange.addOnCompletion(new IdempotentOnCompletion(idempotentRepository, messageId, eager)); |
| |
| // process the exchange |
| processor.process(exchange); |
| } |
| |
| public List<Processor> next() { |
| if (!hasNext()) { |
| return null; |
| } |
| List<Processor> answer = new ArrayList<Processor>(1); |
| answer.add(processor); |
| return answer; |
| } |
| |
| public boolean hasNext() { |
| return processor != null; |
| } |
| |
| // Properties |
| // ------------------------------------------------------------------------- |
| public Expression getMessageIdExpression() { |
| return messageIdExpression; |
| } |
| |
| public IdempotentRepository<String> getIdempotentRepository() { |
| return idempotentRepository; |
| } |
| |
| public Processor getProcessor() { |
| return processor; |
| } |
| |
| // Implementation methods |
| // ------------------------------------------------------------------------- |
| |
| protected void doStart() throws Exception { |
| ServiceHelper.startServices(processor); |
| } |
| |
| protected void doStop() throws Exception { |
| ServiceHelper.stopServices(processor); |
| } |
| |
| /** |
| * A strategy method to allow derived classes to overload the behaviour of |
| * processing a duplicate message |
| * |
| * @param exchange the exchange |
| * @param messageId the message ID of this exchange |
| */ |
| protected void onDuplicateMessage(Exchange exchange, String messageId) { |
| if (LOG.isDebugEnabled()) { |
| LOG.debug("Ignoring duplicate message with id: " + messageId + " for exchange: " + exchange); |
| } |
| } |
| |
| } |