Play 2.1 - Using Concurrent.PatchPannel with a Future

usingPatchPanelWIthFuture.scala

def stream = WebSocket.using[JsValue] { req =>
  val promiseIn = promise[Iteratee[JsValue, Unit]]
  val out = Concurrent.patchPanel[JsValue] { patcher =>
      val in = Iteratee.foreach[JsValue] { json =>
        val topic = // read json and get the topic that the user want to subscribe to
        val streamForThisTopic = // get the corresponding stream (enumerator)
        patcher.patchIn(streamForThisTopic)
      } mapDone { _ => println("Disconnected") }
      
      promiseIn.success(in)
  }
  (Iteratee.flatten(in.future), out)
}