| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.camel; |
| |
| /** |
| * Represents a <a |
| * href="http://camel.apache.org/polling-consumer.html">Polling |
| * Consumer</a> where the caller polls for messages when it is ready. |
| * <p/> |
| * When you are done with the returned {@link Exchange} you must ensure to invoke |
| * {@link org.apache.camel.spi.UnitOfWork#done(Exchange)} to signal to Camel that the {@link Exchange} is done. |
| * <p/> |
| * This is needed to ensure any {@link org.apache.camel.spi.Synchronization} works is being executed. |
| * For example if you consumed from a file endpoint, then the consumed file is only moved/delete when |
| * you done the {@link Exchange}. |
| */ |
| public interface PollingConsumer extends Consumer { |
| |
| /** |
| * Waits until a message is available and then returns it. Warning that this |
| * method could block indefinitely if no messages are available. |
| * <p/> |
| * Will return <tt>null</tt> if the consumer is not started |
| * <p/> |
| * <b>Important: </b> See the class javadoc about the need for done the {@link org.apache.camel.spi.UnitOfWork} |
| * on the returned {@link Exchange} |
| * |
| * @return the message exchange received. |
| */ |
| Exchange receive(); |
| |
| /** |
| * Attempts to receive a message exchange immediately without waiting and |
| * returning <tt>null</tt> if a message exchange is not available yet. |
| * <p/> |
| * <b>Important: </b> See the class javadoc about the need for done the {@link org.apache.camel.spi.UnitOfWork} |
| * on the returned {@link Exchange} |
| * |
| * @return the message exchange if one is immediately available otherwise |
| * <tt>null</tt> |
| */ |
| Exchange receiveNoWait(); |
| |
| /** |
| * Attempts to receive a message exchange, waiting up to the given timeout |
| * to expire if a message is not yet available. |
| * <p/> |
| * <b>Important: </b> See the class javadoc about the need for done the {@link org.apache.camel.spi.UnitOfWork} |
| * on the returned {@link Exchange} |
| * |
| * @param timeout the amount of time in milliseconds to wait for a message |
| * before timing out and returning <tt>null</tt> |
| * |
| * @return the message exchange if one was available within the timeout |
| * period, or <tt>null</tt> if the timeout expired |
| */ |
| Exchange receive(long timeout); |
| } |