NodeJS with Socket.IO delay emitting data

Question

I am using the example from the Socket.IO homepage (http://socket.io/). It works and everything, but there is a huge delay between the time data is sent, and when that data is received on the other end.

I am using XAMPP, I have socket.html in my dir, and navigate to it using "http://localhost/socket.html" in my browser, and I have the server listening on port 8080.

Server:

var io = require('socket.io').listen(8080);

io.sockets.on('connection', function (socket) {
 socket.emit('news', { hello: 'world' });
 socket.on('my other event', function (data) {
   console.log(data);
 });
});

HTML File:

<html>
<head>
    <script src="http://localhost:8080/socket.io/socket.io.js"></script>
    <script>
      var socket = io.connect('http://localhost:8080');
      socket.on('news', function (data) {
        console.log(data);
        socket.emit('my other event', { my: 'data' });
      });
    </script>
</head>

<body>

</body>
</html>

can you define "huge" ? 1 sec 1 min ? which protocol are you using ? — malletjo, Dec 03 '11 at 02:15

score 6 · Accepted Answer · answered Dec 03 '11 at 02:09

I have found the problem.

In the server I changed:

var io = require('socket.io').listen(8080);

to

var io = require('socket.io', { rememberTransport: false, transports: ['WebSocket', 'Flash Socket', 'AJAX long-polling'] }).listen(8080);

which forces the server to use either WebSockets, Flash Sockets, or long-polling. It wil try to use those in that order. The rememberTransport forces the server and client to forget which connection it used last, and try to connect with the 'transports' above.

On the client side I just pretty much did the same thing. I added:

{ rememberTransport: false, transports: ['WebSocket', 'Flash Socket', 'AJAX long-polling']}

to the socket constructor. So it looked like:

var socket = io.connect('http://localhost:843', { rememberTransport: false, transports: ['WebSocket', 'Flash Socket', 'AJAX long-polling']});

Now it seems to work perfectly.

Thanks guys.

For me this disables the connection – Stepan Yakovenko Apr 14 '16 at 12:09 — Stepan Yakovenko, Apr 14 '16 at 12:09

score 1 · Answer 2 · answered Sep 28 '18 at 19:38

Using websockets improves the behavior in the sense that it disables buffering. Websockets is implemented with setNoDelay(true) as can be seen in the websockets code so it will not buffer messages.

You can request websockets explicitly by placing the word websocket first inside the transports array. On recent versions of socket.io and engine.io the correct arguments and implementation looks like this:

import socketIO from 'socket.io';
const server = express();
const requestHandler = server.listen(PORT, () => console.log(`Listening on ${PORT}`));
const io = socketIO(requestHandler, { transports: ['websocket', 'polling'] });

And on the client side:

import io from 'socket.io-client';
let socket = io(SERVER_URL, { transports: ['websocket', 'polling'] });

score 1 · Answer 3 · answered Dec 02 '11 at 15:59

1

Have you tried with a longer message?

There is surely a buffer on the socket. If you send less than X bytes there might be some wait time before the buffer is flushed since it was not filled.

answered Dec 02 '11 at 15:59

msimr-aptgeek

11
1

score 0 · Answer 4 · answered Dec 02 '11 at 02:46

0

What browser are you using? Socket.IO degrades down to polling, which would be much slower than native browser web sockets or flash polling.

answered Dec 02 '11 at 02:46

Justin Thomas

5,680
3
38
63

I am using Google Chrome 15.0.874.121. I have tried it with Firefox and still got the same result. – trentr Dec 03 '11 at 01:10

NodeJS with Socket.IO delay emitting data

4 Answers4

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