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.spi; 018 019 import org.apache.camel.Service; 020 021 /** 022 * Access to a repository of Message IDs to implement the 023 * <a href="http://camel.apache.org/idempotent-consumer.html">Idempotent Consumer</a> pattern. 024 * <p/> 025 * The <tt>add</tt> and <tt>contains</tt> methods is operating according to the {@link java.util.Set} contract. 026 * <p/> 027 * The repository supports eager (default) and non-eager mode. 028 * <ul> 029 * <li>eager: calls <tt>add</tt> and <tt>confirm</tt> if complete, or <tt>remove</tt> if failed</li> 030 * <li>non-eager: calls <tt>contains</tt> and <tt>add</tt> if complete, or <tt>remove</tt> if failed</li> 031 * </ul> 032 * Notice the remove callback, can be configured to be disabled. 033 * 034 * @version 035 */ 036 public interface IdempotentRepository<E> extends Service { 037 038 /** 039 * Adds the key to the repository. 040 * <p/> 041 * <b>Important:</b> Read the class javadoc about eager vs non-eager mode. 042 * 043 * @param key the key of the message for duplicate test 044 * @return <tt>true</tt> if this repository did <b>not</b> already contain the specified element 045 */ 046 boolean add(E key); 047 048 /** 049 * Returns <tt>true</tt> if this repository contains the specified element. 050 * <p/> 051 * <b>Important:</b> Read the class javadoc about eager vs non-eager mode. 052 * 053 * @param key the key of the message 054 * @return <tt>true</tt> if this repository contains the specified element 055 */ 056 boolean contains(E key); 057 058 /** 059 * Removes the key from the repository. 060 * <p/> 061 * Is usually invoked if the exchange failed. 062 * <p/> 063 * <b>Important:</b> Read the class javadoc about eager vs non-eager mode. 064 * 065 * @param key the key of the message for duplicate test 066 * @return <tt>true</tt> if the key was removed 067 */ 068 boolean remove(E key); 069 070 /** 071 * Confirms the key, after the exchange has been processed successfully. 072 * <p/> 073 * <b>Important:</b> Read the class javadoc about eager vs non-eager mode. 074 * 075 * @param key the key of the message for duplicate test 076 * @return <tt>true</tt> if the key was confirmed 077 */ 078 boolean confirm(E key); 079 080 }