Package com.github.ambry.commons

Interface Notifier<T>

Type Parameters:

T - The type of message.

public interface Notifier<T>

A Notifier is a hub that dispatches messages of various topics to TopicListeners. After a TopicListener has subscribed to a topic through the Notifier, a message can be published for that topic, and will be received by the TopicListener. A topic can be subscribed by multiple TopicListener, and a TopicListener can subscribe multiple topics.

Method Summary

Modifier and Type	Method	Description
boolean	publish(java.lang.String topic, T message)	Publishes a message for the specified topic.
void	subscribe(java.lang.String topic, TopicListener<T> listener)	Let a TopicListener subscribe to a topic.
void	unsubscribe(java.lang.String topic, TopicListener<T> listener)	Let a TopicListener unsubscribe from a topic, so it will no longer receive the messages for the topic.

Method Detail

publish

boolean publish(java.lang.String topic,
                T message)

Publishes a message for the specified topic. The TopicListeners that have subscribed to the topic will receive the message.

Parameters:

topic - The topic the message is sent for.

message - The message to send for the topic.

Returns:

true if the message has been sent out successfully, false otherwise.

subscribe

void subscribe(java.lang.String topic,
               TopicListener<T> listener)

Let a TopicListener subscribe to a topic. After subscription, it will receive the messages published for the topic.

Parameters:

topic - The topic to subscribe.

listener - The TopicListener who subscribes the topic.

unsubscribe

void unsubscribe(java.lang.String topic,
                 TopicListener<T> listener)

Let a TopicListener unsubscribe from a topic, so it will no longer receive the messages for the topic.

Parameters:

topic - The topic to unsubscribe.

listener - The TopicListener who unsubscribes the topic.