Package org.apache.pekko.cluster.sharding.typed.javadsl

Class EntityRef<M>

  • All Implemented Interfaces:
    RecipientRef<M>
    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 Actor. 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

      • ask

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

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

      • askWithStatus

        public abstract <Res> java.util.concurrent.CompletionStage<Res> askWithStatus​(scala.Function1<ActorRef<StatusReply<Res>>,​M> f,
                                                                              java.time.Duration timeout)
        The same as <Res>ask(org.apache.pekko.japi.function.Function<org.apache.pekko.actor.typed.ActorRef<Res>,M>,java.time.Duration) but only for requests that result in a response of type pekko.pattern.StatusReply. If the response is a pekko.pattern.StatusReply#success the returned future is completed successfully with the wrapped response. If the status response is a pekko.pattern.StatusReply#error the returned future will be failed with the exception in the error (normally a pekko.pattern.StatusReply.ErrorMessage).

      • getDataCenter

        public java.util.Optional<java.lang.String> getDataCenter()
        The specified datacenter of the incarnation of the particular entity referenced by this EntityRef, if a datacenter was specified.

      • getEntityId

        public java.lang.String getEntityId()
        The identifier for the particular entity referenced by this EntityRef.

      • getTypeKey

        public EntityTypeKey<M> getTypeKey()
        The name of the EntityTypeKey associated with this EntityRef

      • 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>