pubsub not support confirmed for Subscribe

[jxnu-liguobin]

https://github.com/jxnu-liguobin/akka/blob/b0384c646e2024a47056966553ca7d0137a911d1/akka-actor-typed/src/main/scala/akka/actor/typed/internal/pubsub/TopicImpl.scala#L119
In Subscribe,replyTo is not provided for confirming successful registration, but Register support it

    case Subscribe(subscriber) =>
      if (!localSubscribers.contains(subscriber)) {
        context.watchWith(subscriber, SubscriberTerminated(subscriber))
        localSubscribers = localSubscribers + subscriber
        if (localSubscribers.size == 1) {
          context.log.debug(
            "Local subscriber [{}] added, went from no subscribers to one, subscribing to receptionist",
            subscriber)
          // we went from no subscribers to one, register to the receptionist
          receptionist ! Receptionist.Register(topicServiceKey, context.self)
        } else {
          context.log.debug("Local subscriber [{}] added", subscriber)
        }
      } else {
        context.log.debug("Local subscriber [{}] already subscribed, ignoring Subscribe command")
      }
      this

  object Register {

    /**
     * Create a Register without Ack that the service was registered
     */
    def apply[T](key: ServiceKey[T], service: ActorRef[T]): Command =
      new ReceptionistMessages.Register[T](key, service, None)

    /**
     * Create a Register with an actor that will get an ack that the service was registered
     */
    def apply[T](key: ServiceKey[T], service: ActorRef[T], replyTo: ActorRef[Registered]): Command =
      new ReceptionistMessages.Register[T](key, service, Some(replyTo))
  }

[johanandren]

I think that might give a false sense of security/delivery guarantees, because even if held off until the topic has registered and seen a reply from the receptionist, the receptionist on other nodes will not yet have seen that subscriber.

Can you describe a use case where you think the local subscription completing for some meaning of the word would be useful?

[jxnu-liguobin]

I think that might give a false sense of security/delivery guarantees, because even if held off until the topic has registered and seen a reply from the receptionist, the receptionist on other nodes will not yet have seen that subscriber.

Can you describe a use case where you think the local subscription completing for some meaning of the word would be useful?

zio/zio-akka-cluster#11