Package akka.actor.typed.pubsub

Class Topic$

java.lang.Object

akka.actor.typed.pubsub.Topic$

public class Topic$
extends java.lang.Object

A pub sub topic is an actor that handles subscribing to a topic and publishing messages to all subscribed actors.

It is mostly useful in a clustered setting, where it is intended to be started once on every node that want to house subscribers or publish messages to the topic, but it also works in a local setting without cluster.

In a clustered context messages are deduplicated so that there is at most one message sent to each node for each publish and if there are no subscribers on a node, no message is sent to it. Note that the list of subscribers is eventually consistent and there are no delivery guarantees built in.

Each topic results in a ServiceKey in the Receptionist so the same scaling recommendation holds for topics, see docs: https://doc.akka.io/libraries/akka-core/current/typed/actor-discovery.html#receptionist-scalability

Field Summary

Fields

Modifier and Type	Field	Description
static Topic$	MODULE$	Static reference to the singleton instance of this Scala object.

Constructor Summary

Constructors

Constructor	Description
Topic$()

Method Summary

Modifier and Type	Method	Description
<T> Behavior<Topic.Command<T>>	apply(java.lang.String topicName, scala.concurrent.duration.FiniteDuration ttl, scala.reflect.ClassTag<T> classTag)	Scala API: Create a topic actor behavior for the given topic name and message type with a TTL making it terminate itself after a time period with no local subscribers and no locally published messages.
<T> Behavior<Topic.Command<T>>	apply(java.lang.String topicName, scala.reflect.ClassTag<T> classTag)	Scala API: Create a topic actor behavior for the given topic name and message type.
<T> Behavior<Topic.Command<T>>	create(java.lang.Class<T> messageClass, java.lang.String topicName)	Java API: Create a topic actor behavior for the given topic name and message class
<T> Behavior<Topic.Command<T>>	create(java.lang.Class<T> messageClass, java.lang.String topicName, java.time.Duration ttl)	Java API: Create a topic actor behavior for the given topic name and message class with a TTL making it terminate itself after a time period with no local subscribers and no locally published messages.
<T> Topic.Command<T>	getTopicStats(ActorRef<Topic.TopicStats> replyTo)	Java API: Get a summary of the state for a local topic actor.
<T> Topic.Command<T>	publish(T message)	Java API: Publish the message to all currently known subscribers.
<T> Topic.Command<T>	subscribe(ActorRef<T> subscriber)	Java API: Subscribe to this topic.
<T> Topic.Command<T>	unsubscribe(ActorRef<T> subscriber)	Java API: Unsubscribe a previously subscribed actor from this topic.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

MODULE$

public static final Topic$ MODULE$

Static reference to the singleton instance of this Scala object.

Constructor Detail

Topic$

public Topic$()

Method Detail

publish

public <T> Topic.Command<T> publish(T message)

Java API: Publish the message to all currently known subscribers.

subscribe

public <T> Topic.Command<T> subscribe(ActorRef<T> subscriber)

Java API: Subscribe to this topic. Should only be used for local subscribers.

getTopicStats

public <T> Topic.Command<T> getTopicStats(ActorRef<Topic.TopicStats> replyTo)

Java API: Get a summary of the state for a local topic actor.

See TopicStats for caveats

unsubscribe

public <T> Topic.Command<T> unsubscribe(ActorRef<T> subscriber)

Java API: Unsubscribe a previously subscribed actor from this topic.

apply

public <T> Behavior<Topic.Command<T>> apply(java.lang.String topicName,
                                            scala.reflect.ClassTag<T> classTag)

Scala API: Create a topic actor behavior for the given topic name and message type.

Note: for many use cases it is more convenient to use the PubSub registry to have an ActorSystem global set of re-usable topics instead of manually creating and managing the topic actors.

apply

public <T> Behavior<Topic.Command<T>> apply(java.lang.String topicName,
                                            scala.concurrent.duration.FiniteDuration ttl,
                                            scala.reflect.ClassTag<T> classTag)

Scala API: Create a topic actor behavior for the given topic name and message type with a TTL making it terminate itself after a time period with no local subscribers and no locally published messages.

Note: for many use cases it is more convenient to use the PubSub registry to have an ActorSystem global set of re-usable topics instead of manually creating and managing the topic actors.

create

public <T> Behavior<Topic.Command<T>> create(java.lang.Class<T> messageClass,
                                             java.lang.String topicName)

Java API: Create a topic actor behavior for the given topic name and message class

Note: for many use cases it is more convenient to use the PubSub registry to have an ActorSystem global set of re-usable topics instead of manually creating and managing the topic actors.

create

public <T> Behavior<Topic.Command<T>> create(java.lang.Class<T> messageClass,
                                             java.lang.String topicName,
                                             java.time.Duration ttl)

Java API: Create a topic actor behavior for the given topic name and message class with a TTL making it terminate itself after a time period with no local subscribers and no locally published messages.

Note: for many use cases it is more convenient to use the PubSub registry to have an ActorSystem global set of re-usable topics instead of manually creating and managing the topic actors.