Handler.scala

trait RequestFactory {
  def createRequestHeader(
    connection: RemoteConnection,
    method: String,
    target: RequestTarget,
    version: String,
    headers: Headers,
    attrs: TypedMap): RequestHeader
}

trait Stage extends Handler {
  def apply(requestHeader: RequestHeader): (RequestHeader, Handler)
}

trait RequestTaggingHandler extends Handler {
  def tagRequest(request: RequestHeader): RequestHeader
}

private[server] class ForwardedHeaderHandler(configuration: ForwardedHeaderHandlerConfig) {
  def forwardedConnection(rawConnection: RemoteConnection, headers: Headers): RemoteConnection = new RemoteConnection {
}
  
trait EssentialFilter {
  def apply(next: EssentialAction): EssentialAction
}

trait EssentialAction extends (RequestHeader => Accumulator[ByteString, Result]) with Handler

trait WebSocket extends Handler {
  def apply(request: RequestHeader): Future[Either[Result, Flow[Message, Message, _]]]
}