Class EntityRef<M>

  • All Implemented Interfaces:
    RecipientRef<M>
    Direct Known Subclasses:
    EntityRefImpl

    public abstract class EntityRef<M>
    extends java.lang.Object
    implements RecipientRef<M>
    A reference to an sharded Entity, which allows ActorRef-like usage.

    An EntityRef is NOT an ActorRef–by design–in order to be explicit about the fact that the life-cycle of a sharded Entity is very different than a plain Actors. Most notably, this is shown by features of Entities such as re-balancing (an active Entity to a different node) or passivation. Both of which are aimed to be completely transparent to users of such Entity. In other words, if this were to be a plain ActorRef, it would be possible to apply DeathWatch to it, which in turn would then trigger when the sharded Actor stopped, breaking the illusion that Entity refs are "always there". Please note that while not encouraged, it is possible to expose an Actor's self ActorRef and watch it in case such notification is desired.

    Not for user extension.

    • Constructor Detail

      • EntityRef

        public EntityRef()
    • Method Detail

      • asScala

        public EntityRef<M> asScala()
        INTERNAL API
        Returns:
        (undocumented)
      • ask

        public abstract <U> java.util.concurrent.CompletionStage<U> ask​(Function<ActorRef<U>,​M> message,
                                                                        Timeout timeout)
        Allows to "ask" the EntityRef for a reply. See AskPattern for a complete write-up of this pattern

        Note that if you are inside of an actor you should prefer akka.actor.typed.javadsl.ActorContext.ask as that provides better safety.

        Parameters:
        message - (undocumented)
        timeout - (undocumented)
        Returns:
        (undocumented)
      • tell

        public abstract void tell​(M msg)
        Send a message to the entity referenced by this EntityRef using *at-most-once* messaging semantics.
        Specified by:
        tell in interface RecipientRef<M>
        Parameters:
        msg - (undocumented)