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.activemq;
018    
019    import javax.jms.MessageConsumer;
020    
021    /**
022     * A listener which is notified if a message is available for processing via the
023     * receive methods. Typically on receiving this notification you can call 
024     * {@link MessageConsumer#receiveNoWait()} to get the new message immediately.
025     * 
026     * Note that this notification just indicates a message is available for synchronous consumption,
027     * it does not actually consume the message.
028     * 
029     * 
030     */
031    public interface MessageAvailableListener {
032    
033        void onMessageAvailable(MessageConsumer consumer);
034    
035    }