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scalaakkaactor

Difference between forward and tell in akka actors

What is a difference between tell and forward, in case I will send the same message:

case msg: Message =>
  otherActor tell (msg,sender)

and

case msg: Message =>
  otherActor forward msg
Solution

  • The sender() will be different on the receiving end.


    Message sends using tell (also known as !):

    A tells message M to B.
    B tells that message to C.
    C thinks the sender() of message M is B.


    Message sends using forward:

    A tells message M to B.
    B forwards that message to C.
    C thinks the sender() of message M is A.



    Worth pointing out is, that you can achieve the same as forward when explicitly setting the sender of a message using tell, however this is not typical Akka-style:

    // inside `B`, when received `msg` from `A`
C tell (msg, A) 
      == 
C forward msg



    For more info refer to the docs about forward.