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; 018 019 /** 020 * Represents a <a 021 * href="http://activemq.apache.org/camel/polling-consumer.html">Polling 022 * Consumer</a> where the caller polls for messages when it is ready. 023 * 024 * @version $Revision: 35332 $ 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 030 * method 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 and 038 * returning null if a message exchange is not available yet. 039 * 040 * @return the message exchange if one is immediately available otherwise 041 * null 042 */ 043 E receiveNoWait(); 044 045 /** 046 * Attempts to receive a message exchange, waiting up to the given timeout 047 * to expire if a message is not yet available 048 * 049 * @param timeout the amount of time in milliseconds to wait for a message 050 * before timing out and returning null 051 * 052 * @return the message exchange if one iwas available within the timeout 053 * period, or null if the timeout expired 054 */ 055 E receive(long timeout); 056 057 }