001 /** 002 * 003 * Licensed to the Apache Software Foundation (ASF) under one or more 004 * contributor license agreements. See the NOTICE file distributed with 005 * this work for additional information regarding copyright ownership. 006 * The ASF licenses this file to You under the Apache License, Version 2.0 007 * (the "License"); you may not use this file except in compliance with 008 * the License. You may obtain a copy of the License at 009 * 010 * http://www.apache.org/licenses/LICENSE-2.0 011 * 012 * Unless required by applicable law or agreed to in writing, software 013 * distributed under the License is distributed on an "AS IS" BASIS, 014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 015 * See the License for the specific language governing permissions and 016 * limitations under the License. 017 */ 018 package org.apache.camel; 019 020 /** 021 * Represents a <a href="http://activemq.apache.org/camel/polling-consumer.html">Polling Consumer</a> where the caller 022 * polls for messages when it is ready. 023 * 024 * @version $Revision: 1.1 $ 025 */ 026 public interface PollingConsumer<E extends Exchange> extends Consumer<E> { 027 028 /** 029 * Waits until a message is available and then returns it. Warning that this method 030 * could block indefinitely if no messages are available. 031 * 032 * @return the message exchange received. 033 */ 034 E receive(); 035 036 /** 037 * Attempts to receive a message exchange immediately without waiting 038 * and returning null if a message exchange is not available yet. 039 * 040 * @return the message exchange if one is immediately available otherwise null 041 */ 042 E receiveNoWait(); 043 044 /** 045 * Attempts to receive a message exchange, waiting up to the given timeout to expire 046 * if a message is not yet available 047 * 048 * @param timeout the amount of time in milliseconds to wait for a message before timing out and 049 * returning null 050 * 051 * @return the message exchange if one iwas available within the timeout period, or null if the timeout expired 052 */ 053 E receive(long timeout); 054 055 }