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/*
* Copyright (c) 2008-2020, 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.topic;
import com.hazelcast.core.DistributedObject;
import jakarta.annotation.Nonnull;
import java.util.Collection;
import java.util.UUID;
import java.util.concurrent.CompletionStage;
import java.util.concurrent.ExecutionException;
/**
* Hazelcast provides distribution mechanism for publishing messages that are
* delivered to multiple subscribers, which is also known as a publish/subscribe
* (pub/sub) messaging model. Publish and subscriptions are cluster-wide.
*
* When a member subscribes for a topic, it is actually registering for messages
* published by any member in the cluster, including the new members joined after
* you added the listener.
*
* Messages are ordered, meaning that listeners(subscribers) will process the
* messages in the order they are actually published. If cluster member M
* publishes messages m1, m2, m3...mn to a topic T, then Hazelcast makes sure
* that all of the subscribers of topic T will receive and process m1, m2,
* m3...mn in order.
*
* Since Hazelcast 3.5 it is possible to have reliable topics. Normally all
* topics rely on the shared eventing system and shared threads. With Hazelcast
* 3.5 it is possible to configure a topic to be reliable and to get its own
* {@link com.hazelcast.ringbuffer.Ringbuffer} to store events and to get its
* own executor to process events. The events in the ringbuffer are replicated,
* so they won't get lost when a node goes down.
*
* @param the type of the message
*/
public interface ITopic extends DistributedObject {
/**
* Returns the name of this ITopic instance.
*
* @return name of this ITopic instance
*/
String getName();
/**
* Publishes the message to all subscribers of this topic.
*
* @param message the message to publish to all subscribers of this topic
* @throws TopicOverloadException if the consumer is too slow
* (only works in combination with reliable topic)
*/
void publish(@Nonnull E message);
/**
* Publishes the message asynchronously to all subscribers of this topic.
*
* @param message the message to publish asynchronously to all subscribers of this topic
* @return the CompletionStage to synchronize on completion.
*/
CompletionStage publishAsync(@Nonnull E message);
/**
* Subscribes to this topic. When a message is published, the
* {@link MessageListener#onMessage(Message)} method of the given
* MessageListener is called.
* More than one message listener can be added on one instance.
* See {@link ReliableMessageListener} to better integrate with a reliable topic.
*
* @param listener the MessageListener to add
* @return returns the registration ID
* @throws java.lang.NullPointerException if listener is {@code null}
*/
@Nonnull
UUID addMessageListener(@Nonnull MessageListener listener);
/**
* Stops receiving messages for the given message listener.
*
* If the given listener already removed, this method does nothing.
*
* @param registrationId ID of listener registration
* @return {@code true} if registration is removed, {@code false} otherwise
*/
boolean removeMessageListener(@Nonnull UUID registrationId);
/**
* Returns statistics about this topic, like total number of publishes/receives.
* The statistics are local to this member and represent the activity on
* this member, not the entire cluster.
*
* @return statistics about this topic
*/
@Nonnull LocalTopicStats getLocalTopicStats();
/**
* Publishes all messages to all subscribers of this topic.
*
* @param messages the messages to publish to all subscribers of this topic
* @throws TopicOverloadException if the consumer is too slow
* (only works in combination with reliable topic)
*/
void publishAll(@Nonnull Collection messages) throws ExecutionException, InterruptedException;
/**
* Publishes all messages asynchronously to all subscribers of this topic.
*
* @param messages the messages to publish asynchronously to all subscribers of this topic
* @return the CompletionStage to synchronize on completion.
*/
CompletionStage publishAllAsync(@Nonnull Collection messages);
}