How to use actor inside of spray route in REST service? - scala

Question

I'm trying to build event sourced service with REST interface using scala. I somewhat new to scala, although I'm familiar with functional programming (haskell at beginner level).
So I've build persistent actor and view without major problems. The idea of actors is quite simple I think.
object Main extends App {
val system = ActorSystem("HelloSystem")
val systemActor = system.actorOf(Props[SystemActor], name = "systemactor")
val trajectoryView = system.actorOf(Props[TrajectoryView], name = "trajectoryView")
var datas = List()
val processData = ProcessData(0, List(1,2,3), Coordinates(50, 50))
implicit val timeout = Timeout(5 seconds)
def intialDatas(): List[ProcessData] =
(for (i <- 1 to 3) yield ProcessData(i, List(1,2,3), Coordinates(50 + i, 50 + i)))(collection.breakOut)
val command = RegisterProcessCommand(3, this.intialDatas())
val id = Await.result(systemActor ? command, timeout.duration).asInstanceOf[String]
println(id)
systemActor ! MoveProcessCommand(4, ProcessData(4, List(3,4,5), Coordinates(54, 54)), id)
val processes = Await.result(systemActor ? "get", timeout.duration).asInstanceOf[Set[Process]]
println(processes)
implicit val json4sFormats = DefaultFormats
println(write(processes))
println("*****************")
systemActor ! "print"
val getTrajectoryCommand = GetTrajectoryCommand(id)
Thread.sleep(10000)
trajectoryView ! "print"
// val trajectory = Await.result(trajectoryView ? getTrajectoryCommand, timeout.duration).asInstanceOf[ListBuffer[Coordinates]]
println("******* TRAJECTORY *********")
trajectoryView ! "print"
// println(trajectory)
system.shutdown()
}
I've been able to create a script for playing with actor that I've created.
I've read the tutorials for spray routing, but I've been unable to grasp what exactly should I do to provide REST interface for actors that I've created.
object Boot extends App{
implicit val system = ActorSystem("example")
val systemActor = system.actorOf(Props[SystemActor], name = "systemactor")
val trajectoryView = system.actorOf(Props[TrajectoryView], name = "trajectoryView")
val service = system.actorOf(Props[ProcessesService], "processes-rest-service")
implicit val timeout = Timeout(5 seconds)
IO(Http) ? Http.Bind(service, interface = "localhost", port = 8080)
}
And a service
class ProcessesService(systemActor: ActorRef) extends Actor with HttpService {
def actorRefFactory = context
def receive = runRoute(route)
val json4sFormats = DefaultFormats
implicit val timeout = Timeout(5 seconds)
val route = path("processes") {
get {
respondWithMediaType(`application/json`) {
complete {
write(Await.result(systemActor ? "get", timeout.duration).asInstanceOf[Set[Process]])
}
}
}
}
}
I think I need to somehow pass actorRef for SystemActor to this ProcessesService, but I'm not sure how. Also I'm not sure how should I return a response to the request. I understand that I need to somehow pass the "get" message to SystemActor through ActorRef and then serialize the answer to json, but I don't know how to do that.
I would appreciate help!

Answer 1

In spray you can complete routes with a Future.
You should be able to do something like
complete { systemActor ? "get" }
Json serialization is a separate issue.
Oh, your question is vague. Yes you need to be able to reference an actor within your routes. You could just import the val from boot where you define it. They're just Scala variables so where you put them is up to you.