Combining Spray Routing + Actor Pattern Matching - scala

Question

Following the Akka Cluster documentation, I have the Worker Dial-in example running.
http://doc.akka.io/docs/akka/snapshot/java/cluster-usage.html
So I've trying to integrate that with a spray routing.
My idea is to have a cluster behind the scenes and through a http rest, call that service.
So I have the following code.
object Boot extends App {
val port = if (args.isEmpty) "0" else args(0)
val config =
ConfigFactory
.parseString(s"akka.remote.netty.tcp.port=$port")
.withFallback(ConfigFactory.parseString("akka.cluster.roles = [frontend]"))
.withFallback(ConfigFactory.load())
val system = ActorSystem("ClusterSystem", config)
val frontend = system.actorOf(Props[TransformationFrontend], name = "frontend")
implicit val actSystem = ActorSystem()
IO(Http) ! Http.Bind(frontend, interface = config.getString("http.interface"), port = config.getInt("http.port"))
}
class TransformationFrontend extends Actor {
var backends = IndexedSeq.empty[ActorRef]
var jobCounter = 0
implicit val timeout = Timeout(5 seconds)
override def receive: Receive = {
case _: Http.Connected => sender ! Http.Register(self)
case HttpRequest(GET, Uri.Path("/job"), _, _, _) =>
jobCounter += 1
val backend = backends(jobCounter % backends.size)
val originalSender = sender()
val future : Future[TransformationResult] = (backend ? new TransformationJob(jobCounter + "-job")).mapTo[TransformationResult]
future onComplete {
case Success(s) =>
println("received from backend: " + s.text)
originalSender ! s.text
case Failure(f) => println("error found: " + f.getMessage)
}
case job: TransformationJob if backends.isEmpty =>
sender() ! JobFailed("Service unavailable, try again later", job)
case job: TransformationJob =>
jobCounter += 1
backends(jobCounter % backends.size) forward job
case BackendRegistration if !backends.contains(sender()) =>
println("backend registered")
context watch sender()
backends = backends :+ sender()
case Terminated(a) =>
backends = backends.filterNot(_ == a)
}
}
But what I really want to do is to combining the spray routing with those pattern matching.
Instead of writing my GET like the above, I would like to write like this:
path("job") {
get {
respondWithMediaType(`application/json`) {
complete {
(backend ? new TransformationJob(jobCounter + "-job")).mapTo[TransformationResult]
}
}
}
}
But extending my Actor with this class, I have to do the following
def receive = runRoute(defaultRoute)
How can I combine this approach with my TransformationFrontend Actor pattern matching methods? BackendRegistration, Terminated, TransformationJob?

Answer 1

You can compose PartialFunctions like Receive with PartialFunction.orElse:
class TransformationFrontend extends Actor {
// ...
def myReceive: Receive = {
case job: TransformationJob => // ...
// ...
}
def defaultRoute: Route =
get {
// ...
}
override def receive: Receive = runRoute(defaultRoute) orElse myReceive
}
That said, it often makes sense to split up functionality into several actors (as suggested in the comment above) if possible.