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 * 027 * @version 028 */ 029 public interface IdempotentRepository<E> extends Service { 030 031 /** 032 * Adds the key to the repository. 033 * 034 * @param key the key of the message for duplicate test 035 * @return <tt>true</tt> if this repository did <b>not</b> already contain the specified element 036 */ 037 boolean add(E key); 038 039 /** 040 * Returns <tt>true</tt> if this repository contains the specified element. 041 * <p/> 042 * This operation is used if the option <tt>eager</tt> has been enabled. 043 * 044 * @param key the key of the message 045 * @return <tt>true</tt> if this repository contains the specified element 046 */ 047 boolean contains(E key); 048 049 /** 050 * Removes the key from the repository. 051 * <p/> 052 * Is usually invoked if the exchange failed. 053 * 054 * @param key the key of the message for duplicate test 055 * @return <tt>true</tt> if the key was removed 056 */ 057 boolean remove(E key); 058 059 /** 060 * Confirms the key, after the exchange has been processed successfully. 061 * <p/> 062 * This operation is used if the option <tt>eager</tt> has been enabled. 063 * 064 * @param key the key of the message for duplicate test 065 * @return <tt>true</tt> if the key was confirmed 066 */ 067 boolean confirm(E key); 068 069 }