io.atomix.group.messaging

Interface MessageConsumer<T>

All Superinterfaces:

AutoCloseable

public interface MessageConsumer<T>
extends AutoCloseable

Consumes messages from a named message queue.

Consumers receive messages sent by MessageProducers to specific named queues. Messages are pushed to consumers through Copycat's session event protocol.

To listen for messages received by a consumer, register a message listener via the onMessage(Consumer) method:

   
   MessageConsumer<String> consumer = localMember.messaging().consumer("foo");
   consumer.onMessage(message -> {
     // ...
     message.ack();
   });
   
 

Consumer callbacks will be called with a unique Message object. Each message consumed by a consumer is guaranteed to have a unique Message.id(). It is the responsibility of every consumer to either ack or reply to every message. Failure to ack or reply to a message will result in a memory leak and the failure to publish messages to a member.

Author:

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static class	MessageConsumer.Options Message consumer options.

Method Summary

Modifier and Type	Method and Description
default void	close() Closes the consumer.
Listener<Message<T>>	onMessage(Consumer<Message<T>> callback) Registers a listener for messages received by the consumer.

Method Detail

onMessage

Listener<Message<T>> onMessage(Consumer<Message<T>> callback)

Registers a listener for messages received by the consumer.

Messages are received by consumers through Copycat's session event protocol. Each message is guaranteed to be received by the consumer on the same thread, and consumed Messages are guaranteed to have unique ids. It is the responsibility of every consumer to either ack or reply to every message. Failure to ack or reply to a message will result in a memory leak and the failure to publish messages to a member.

Parameters:

callback - The message listener callback.

Returns:

The message listener.

Throws:

NullPointerException - if the listener callback is null

close

default void close()

Closes the consumer.

When the consumer is closed, the consumer will be removed from the list of consumers for the parent MessageService and messages will no longer be delivered to this consumer.

Specified by:

close in interface AutoCloseable