How to complete a request in another actor when using akka-http

Question

I am using akka-http 1.0 and I would like to use a route defined as

def route: Route = path("") {
  // start actor with requestContext
  // call requestContext.complete(...) in actor with the result
}

How do I accomplish this?

Answer 1

Elaborating on @jrudolph's comment, the below code satisfies your requirements of dispatching RequestContext values to an Actor. Your question indicated that you wanted a new Actor for each request; however, the below code uses the same Actor for all requests which I think is a more efficient/likely use case. The Actor creation can always be moved inside handleRequest if needed.

First we need an Actor for processing a request to a response:

import akka.actor.Actor
import akka.http.scaladsl.server.{RequestContext, RouteResult}
import akka.http.scaladsl.model.HttpResponse

class RequestActor extends Actor {

  //business logic - returns empty HttpResponse
  def handleRequestMessage(requestContext : RequestContext) = 
    RouteResult.Complete(new HttpResponse())

  override def receive = {
    case reqContext : RequestContext => 
      sender ! handleRequestMessage(reqContext)
  }
}//end class RequestActor

Now create a utility function for querying the Actor:

import akka.actor.ActorRef
import scala.concurrent.Future
import akka.pattern.ask

object RequestActor {
  val handleRequest : ActorRef => RequestContext => Future[RouteResult] =
    (actorRef) =>
      (requestContext) =>
        ask(actorRef,reqContext).mapTo[RouteResult]
}

And all that is left to do is wire everything together into a service:

import akka.actor.{ActorSystem, Props}
import akka.stream.ActorMaterializer
import akka.http.scaladsl.Http
import akka.http.scaladsl.server.Directives.{get,path}
import akka.util.Timeout

object RouteActorTest extends App {
  implicit val as = ActorSystem("RouteActorTest")
  implicit val timeout = new Timeout(1000)

  val sendRequestToActor : RequestContext => Future[RouteResult] = 
    RequestActor handleRequest (as actorOf Props[RequestActor])      

  val route = path("")(get(sendRequestToActor))

  //rest of application...

}//end object RouteActorTest