Getting the Future of the ProductVersion of the server offering the requested URI

RequestLevelApiDemo.scala

  def requestProductVersion(uri: String)(implicit system: ActorSystem): Future[ProductVersion] = {
    val uriCompleted = if(uri.indexOf('/') < 0) uri+'/' else uri
    import system.dispatcher  // execution context for future transformation below
    val startTime = Platform.currentTime
    for {
      response <- IO(Http).ask(HttpRequest(GET, Uri(s"http://$uri"))).mapTo[HttpResponse]
      _ <- IO(Http) ? Http.CloseAll
    } yield {
      val startAtMillis = startTime - system.startTime
      val durationInMillis = Platform.currentTime - startTime
      system.log.info(s"Get URI $uri responded '${response.status}' with ${response.entity.data.length} bytes. Started at $startAtMillis ms, lasted $durationInMillis ms.")
      response.header[HttpHeaders.Server].get.products.head
    }
  }