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 /**
020 * Access to a repository of Message IDs to implement the
021 * <a href="http://camel.apache.org/idempotent-consumer.html">Idempotent Consumer</a> pattern.
022 * <p/>
023 * The <tt>add</tt> and <tt>contains</tt> methods is operating according to the {@link java.util.Set} contract.
024 *
025 * @version $Revision: 738604 $
026 */
027 public interface IdempotentRepository<E> {
028
029 /**
030 * Adds the key to the repository.
031 *
032 * @param key the key of the message for duplicate test
033 * @return <tt>true</tt> if this repository did <b>not</b> already contain the specified element
034 */
035 boolean add(E key);
036
037 /**
038 * Returns <tt>true</tt> if this repository contains the specified element.
039 *
040 * @param key the key of the message
041 * @return <tt>true</tt> if this repository contains the specified element
042 */
043 boolean contains(E key);
044 }