Play Framework Dynamic Akka Streams Source

PlayDynamicSource.scala

def streamWithQueue = Action {

  implicit val myExecutionContext: ExecutionContext = actorSystem.dispatchers.lookup("queue-context")

  val (queue: SourceQueueWithComplete[String], source: Source[String, NotUsed]) = {
    Source.queue[String](100, OverflowStrategy.backpressure).preMaterialize
  }

  // simulate a background process feeding the queue
  Future.traverse((1 to 1000).toList) { i =>
    // sleep just for the example, to see numbers be displayed one by one in streaming
    Future(Thread.sleep(1000)).flatMap { _ =>
      println("add " + i)
      queue.offer(i.toString)
    }
  }.map(_ => queue.complete())
    
  Ok.chunked(source)
}