No easy way to send a reply to caller actor ?

[coldwarrl]

Hi,

in akka, I can just use the handle sender to send a reply message like
sender.Tell(my_reply)

Do I have to implement my own protocol (e.g. add result actor field in message struct) to be able to send a response to the calling actor ?

Thanks!

[slawlor]

You can see an example in https://slawlor.github.io/ractor/quickstart/#adding-state

But the short answer is your message type needs to include the reply channel which is an RpcReplyPort<_> and the actor uses that to send the reply back.

The caller just needs to use either the call! macro or ActorRef<_>.call which will handle sending the message and waiting for the reply.

[coldwarrl]

Thanks! I have overseen that.

Is this the Erlang way to do this, or is there any reason not include the sender like in Akka ? My experience with actors are solely from Akka/Akka.net...

[slawlor]

In Erlang they would send the actor along with a reference to the specific message. This is because the caller is likely blocking on the reply, so the runtime needs to match up the sent message with the received reply. We do this by using a channel, which is semantically the same, and if you wanted you could construct the channel and not wait on a reply right away if you were doing say other work while that processing was occurring.

You also could send an actor ref instead of a channel and your downstream actor just sends a blind message back to that actor, which sounds like what it's doing in akka. The problem is then you have to match up the message to the reply manually which can be annoying sometimes