nim-websock/examples/server.nim

 import pkg/[chronos,
             chronos/apps/http/httpserver,
             chronicles,
             httputils,
             stew/byteutils]
import ../src/ws

proc process(r: RequestFence): Future[HttpResponseRef] {.async.} =
  if r.isOk():
    let request = r.get()
    debug "Handling request:", uri = request.uri.path
    if request.uri.path == "/ws":
      debug "Initiating web socket connection."
      try:
        var ws = await createServer(request,"")
        if ws.readyState != Open:
          error "Failed to open websocket connection."
          return
        debug "Websocket handshake completed."
        while ws.readyState != ReadyState.Closed:
          # Only reads header for data frame.
          var recvData = await ws.recv()
          if recvData.len <= 0:
            debug "Empty messages"
            break

          # debug "Client Response: ", data = string.fromBytes(recvData), size = recvData.len
          debug "Client Response: ", size = recvData.len
          await ws.send(recvData)
          # await ws.close()
          
      except WebSocketError as exc:
        error "WebSocket error:", exception = exc.msg
    discard await request.respond(Http200, "Hello World")
  else:
    return dumbResponse()

when isMainModule:
  let address = initTAddress("127.0.0.1:8888")
  let socketFlags = {ServerFlags.TcpNoDelay, ServerFlags.ReuseAddr}
  let res = HttpServerRef.new(
    address, process,
    socketFlags = socketFlags)
 
  let server = res.get()
  server.start()
  info "Server listening at ", data = address
  waitFor server.join()