Hello there, In general always perfer tell (!) instead of ask (?), unless you have a compelling reason not to. It has less overhead, and I also find things nicer to model using plain actor tell's instead of ask's - which mix up styles a little bit (actors in general "fire and forget").
But let's also look at your example, because I think you may have mixed up what Future[_] gets completed when. The futures don't automatically get composed, but by chanining of reactions to a futures completion, actors can "cascade" completing their corresponding futures. In the bellow example we use ask twice. The a actor completes the fa future, but only once the fb future completes successfuly. Completing an "ask created Future", happens when an actor replies to the message sent by ask - so in the end => b completes the fb future, which then triggers the map in a, which completes the fa future. import akka.pattern.ask val b = context.system.actorOf(Props(new Actor { def receive = { case s => sender() ! s // this response completes the `fb` future } })) val a = context.system.actorOf(Props(new Actor { def receive = { case s => val replyTo = sender() val fb = b ? (s + "!") fb map { bResponse => // this runs when the b actor replies - thus, completing the `fb` future replyTo ! bResponse // this completes the `fa` future } } })) val fa: Future[Any] = a ? "wat" // this future will be completed by the `a` actor replying to the "wat" message -- Konrad Malawski geecon.org / java.pl / krakowscala.pl / gdgkrakow.pl From: glidester glides...@gmail.com Reply: akka-user@googlegroups.com akka-user@googlegroups.com Date: 21 March 2014 at 11:49:05 To: akka-user@googlegroups.com akka-user@googlegroups.com Subject: [akka-user] Chaining actor ask calls Hi, I'm in the process of learning Akka and I wondered if anyone could clarify something for me. If I have 2 actors. I 'ask' Actor A which in turn 'asks' Actor B. This means I get returned a Future from ActorB wrapped in a Future from Actor A (correct?) Is this good practice? Should I be using "tell" instead to avoid the nested Futures? Any pointers gratefully received! G -- >>>>>>>>>> Read the docs: http://akka.io/docs/ >>>>>>>>>> Check the FAQ: >>>>>>>>>> http://doc.akka.io/docs/akka/current/additional/faq.html >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user --- You received this message because you are subscribed to the Google Groups "Akka User List" group. To unsubscribe from this group and stop receiving emails from it, send an email to akka-user+unsubscr...@googlegroups.com. To post to this group, send email to akka-user@googlegroups.com. Visit this group at http://groups.google.com/group/akka-user. For more options, visit https://groups.google.com/d/optout. -- >>>>>>>>>> Read the docs: http://akka.io/docs/ >>>>>>>>>> Check the FAQ: >>>>>>>>>> http://doc.akka.io/docs/akka/current/additional/faq.html >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user --- You received this message because you are subscribed to the Google Groups "Akka User List" group. To unsubscribe from this group and stop receiving emails from it, send an email to akka-user+unsubscr...@googlegroups.com. To post to this group, send email to akka-user@googlegroups.com. Visit this group at http://groups.google.com/group/akka-user. For more options, visit https://groups.google.com/d/optout.