Simple beginner questions: Accessing values in flows

[mniel...@gmail.com]

I have the following code:

val cmdSrc: Source[Message, ActorRef] = Source.actorRef[Message](10, OverflowStrategy.fail)

val wsr: WebSocketRequest = WebSocketRequest(myEndpoint)

val webSocketFlow: Flow[Message, Message, Future[WebSocketUpgradeResponse]] = Http().webSocketClientFlow(wsr)

val webSocketGraph: RunnableGraph[(ActorRef, Future[Done])] = cmdSrc.via(webSocketFlow).toMat(printSink)(Keep.both)

val (actorRef, fd): (ActorRef, Future[Done]) = webSocketGraph.run()

The idea is that I want to send messages to actorRef that are then sent through the flow.

This code produces the required result, but its an early and amateurish attempt as I try to understand Akka.

My questions are:

• Is this somewhere near the accepted idiom, or is there a better representation of the same thing?
• How do I get my hands on the Future[WebSocketUpgradeResponse] from webSocketFlow (line 3)?

Thanks!

[mniel...@gmail.com]

Actually, I worked it out.  Thanks!

[Evgeny Shepelyuk]

Hi, could you please spare final code ?

[mniel...@gmail.com]

So, rightly or wrongly, I did this, which seems to work:

 val flow = builder.add(wsl.mapMaterializedValue(f => {

          f map {

            u => if (u.response.status == StatusCodes.SwitchingProtocols) {

              log.info("Switched protocols")

            }

            else

              throw new IllegalStateException("Did not switch")

          }

})

The key bit is the mapMaterializedValue inside the builder.add.

Whether this is how one is intended to do it is another matter, but so far the result has proven satisfactory.