Scala 的 HTTP 服務接口：http4s

// Make your model safe and streaming by using a scalaz-stream Process
def getData(req: Request): Process[Task, String] = ???

val service: HttpService = {
  // Wire your data into your service
  case GET -> Root / "streaming" => Ok(getData(req))

  // You can use helpers to send any type of data with an available Writable[T]
  case GET -> Root / "synchronous" => Ok("This is good to go right now.")
}

val route: HttpService = {
  case req@ GET -> Root / "ws" =>
    // Send a Text message with payload 'Ping!' every second
    val src = Process.awakeEvery(1.seconds).map{ d => Text(s"Ping! $d") }

    // Print received Text frames, and, on completion, notify the console
    val sink: Sink[Task, WSFrame] = Process.constant {
      case Text(t) => Task.delay(println(t))
      case f       => Task.delay(println(s"Unknown type: $f"))
    }.onComplete(Process.eval(Task{ println("Terminated!")}).drain)

    // Use the WS helper to make the Task[Response] carrying the info
    // needed for the backend to upgrade to a WebSocket connection
    WS(src, sink)

  case req @ GET -> Root / "wsecho" =>
    // a scalaz topic acts as a hub to publish and subscribe to messages safely
    val t = topic[WSFrame]
    val src = t.subscribe.collect{ case Text(msg) => Text("You sent the server: " + msg) }
    WS(src, t.publish)
}