ws: websocket server unable to handle requests immediately after server startup.

• I’ve searched for any related issues and avoided creating a duplicate issue.

• I’ve checked to make sure this is the module with the issue.

Description

Server completes handshake with client websocket before being able to handle messages from client immediately after server startup.

Reproducible in:

version: 5.2.0

Node.js version(s):8.9.4

OS version(s): OSX 10.12.6 (MacOS High Sierra)

Steps to reproduce:

1. mount express-ws on server
2. have client continually try to connect to websocket server while server is starting.

Expected result:

Messages sent by client after handshake are handled by the server immediately after server startup.

Actual result:

Messages sent by client after handshake are never handled by the server (websocket is opened appropriately). The function connectionHandler defined in the app.ws(path, connectionHandler) is never called with the messages.

If client delays the sending of these messages by a small amount of time (around 50 milliseconds on my computer) the server handles the messages appropriately.

Attachments:

---

Server

server sample code

//import ws
const enableWs = require('express-ws')

//lots of extraneous code

//attach ws to server
enableWs(app, server)
app.ws('/ws', webSocketConnectionHandler) //see below

//more extraneous code

//tell the server to listen on port
server.listen(port, ()=> {
  console.log(`server listening on port ${port}`)
});

webSocketConnectionHandler

function wsConnectionHandler(ws, req) {

  //prevent websocket closing from crashing the server
  ws.on('close', () => {})

  //prevent websocket error from crashing the server
  ws.on('error', (error) => {})

  ws.on('message', message => {
    console.log(message) //verifying the message was received
    webSocketMessageHandler(message, getDefaultMessageHandlers(ws, req), ws) //handle message
  })
}

---

Client (not working, but should) - Java

//simplified a lot
class webSocket extends WebSocketClient {

  public webSocket(String url) {
    super(new URI(url), new Draft_6455(), getHeaders(), 0);
  }

  private boolean alreadyConnecting = false;

  //runs once websocket successfully opens (handshake successful)
  public void onOpen(ServerHandshake serverHandshake) {
    this.send("Hello World"); //this message is not handled by the server but should

    Timer timer = new Timer(true);
    timer.schedule(new TimerTask() { // delays sending of message over websocket for 50 milliseconds
        @Override
        public void run() {
            this.send("Hola Teirra"); //this message is handled by the server
            timer.cancel();
        }
    }, 50);
  }

  //once websocket closes or fails to initially connect, keep trying to reconnect until successful
  public void onClose() {
    if (alreadyConnecting) {
      return;
    }

    this.alreadyConnecting = true;

    Timer timer = new Timer(true);
    timer.scheduleAtFixedRate(new TimerTask() { //try to reconnect every second

      @Override
      public void run() {
          try {
              if (this.reconnectBlocking()) {
                  this.alreadyConnecting = false;
                  timer.cancel();
              }
          } catch (InterruptedException e) {
              e.printStackTrace();
          }
        }
    }, 0, 1000);

  }
}

What happens:

The "Hello world" message is sent by the client after handshake completes and websocket successfully opens, however the "Hello world" message is never handled by the server. The "Hola Teirra" message is sent 50 milliseconds after the websocket successfully opens and the message is successfully handled by the server. I have verified that the client successfully sends both messages.