com.hazelcast.core.MessageListener Maven / Gradle / Ivy
/*
* Copyright (c) 2008-2016, Hazelcast, Inc. All Rights Reserved.
*
* Licensed 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 com.hazelcast.core;
import java.util.EventListener;
/**
* Message listener for {@link ITopic}.
*
* Provided that a MessageListener is not registered twice, a MessageListener will never be called concurrently. So there
* is no need to provide thread-safety on internal state in the MessageListener. Also there is no need to enforce safe
* publication, the ITopic is responsible for the memory consistency effects. In other words, there is no need to make
* internal fields of the MessageListener volatile or access them using synchronized blocks.
*
* @param message
*/
public interface MessageListener extends EventListener {
/**
* Invoked when a message is received for the added topic. Note that topic guarantees message ordering.
* Therefore there is only one thread invoking onMessage. The user should not keep the thread busy, but preferably
* should dispatch it via an Executor. This will increase the performance of the topic.
*
* @param message the message that is received for the added topic
*/
void onMessage(Message message);
}