Websockets example

ApiController.scala

// in ApiController body

def checkStream: WebSocket = WebSocket.accept[JsValue, JsValue] { _ =>
  ActorFlow.actorRef(out =>
    CheckStreamActor.props(out, matcherPool)
    ,
    // A large buffer is necessary to ensure messages aren't dropped -- see
    // https://github.com/playframework/playframework/issues/6246.
    10000)
}

CheckStreamActor.scala

package actors

import model.{Check, MatcherError, MatcherWorkComplete}
import play.api.libs.json.{JsValue, Json}
import services._

import scala.concurrent.ExecutionContext
import akka.actor._
import akka.stream.Materializer
import akka.stream.scaladsl.Sink

object CheckStreamActor {
  def props(out: ActorRef, pool: MatcherPool)(implicit ec: ExecutionContext, mat: Materializer) = Props(new CheckStreamActor(out, pool))
}

class CheckStreamActor(out: ActorRef, pool: MatcherPool)(implicit ec: ExecutionContext, implicit val mat: Materializer) extends Actor {
  def receive: PartialFunction[Any, Unit] = {
    case jsValue: JsValue =>
      jsValue.validate[Check].asEither match {
        case Right(check) => {
          pool.checkStream(check).map {
            out ! Json.toJson(_)
          }.runWith(Sink.ignore).onComplete { _ =>
            out ! Json.toJson(MatcherWorkComplete())
            out ! Success
          }
        }
        case Left(error) => {
          out ! Json.toJson(MatcherError(s"Error parsing websocket input: $error"))
          out ! Failure
        }
      }
  }
}