WebSocket connection failed: Error during WebSocke

Question

I am trying to integrate Socket.io with Angular and I'm having difficulties making a connection from the client-side to the server. I've looked through other related questions but my issue is happening locally, so there's no web server in the middle.

This is what my server code looks like:

const app = express();
const server = http.createServer(app);
const io = require('socket.io').listen(server);

io.on('connection', function(socket) {
  socket.emit('greet', { hello: 'Hey, Mr.Client!' });

  socket.on('respond', function(data) {
    console.log(data);
  });
  socket.on('disconnect', function() {
    console.log('Socket disconnected');
  });
});

I'm loading the client side JavaScript files using Grunt in the following order:

dist: {
    src: [
        public/bower_components/angular/angular.min.js,
        ...
        public/bower_components/socket.io-client/dist/socket.io.min.js,
        public/bower_components/angular-socket-io/socket.min.js,
        ...
    ]
}

Then in my controller:

function MyController($scope) {

    let socket = io.connect(window.location.href);
    socket.connect('http://localhost:3000');
    socket.on('greet', function(data) {
      console.log(data);
      socket.emit('respond', { message: 'Hello to you too, Mr.Server!' });
    });

    ...
}

Before actually using the btford/angular-socket-io library, I want to make sure that I can get a connection correctly, but I get the following error in the console:

The interesting thing is that if I restart the Node.js server process, it does manage to send the message but using polling instead of websockets.

I tried all sorts of different options in the socket.connect call, but nothing worked.

Any help would be appreciated.

---

UPDATE (30/12/2016):

I just realized that websockets is working partially. I see a 101 Switching Protocols request in the Chrome developer console. However the only frames I see there are the engine.io protocol packets (ping, pong). However my application socket messages still fall back to polling for some reason...

Answer 1

Judging from the messages you send via Socket.IO socket.emit('greet', { hello: 'Hey, Mr.Client!' });, it seems that you are using the hackathon-starter boilerplate. If so, the issue might be that express-status-monitor module is creating its own socket.io instance, as per: https://github.com/RafalWilinski/express-status-monitor#using-module-with-socketio-in-project

You can either:

1. Remove that module

2. Pass in your socket.io instance and port as websocket when you create the expressStatusMonitor instance like below:

   const server = require('http').Server(app);
   const io = require('socket.io')(server);
   ...
   app.use(expressStatusMonitor({ websocket: io, port: app.get('port') })); 
   

Answer 2

Problem solved! I just figured out how to solve the issue, but I would still like to know if this is normal behavior or not.

It seems that even though the Websocket connection establishes correctly (indicated by the 101 Switching Protocols request), it still defaults to long-polling. The fix was as simple as adding this option to the Socket.io connection function:

{transports: ['websocket']}

So the code finally looks like this:

const app = express();
const server = http.createServer(app);
var io = require('socket.io')(server);

io.on('connection', function(socket) {
  console.log('connected socket!');

  socket.on('greet', function(data) {
    console.log(data);
    socket.emit('respond', { hello: 'Hey, Mr.Client!' });
  });
  socket.on('disconnect', function() {
    console.log('Socket disconnected');
  });
});

and on the client:

var socket = io('ws://localhost:3000', {transports: ['websocket']});
socket.on('connect', function () {
  console.log('connected!');
  socket.emit('greet', { message: 'Hello Mr.Server!' });
});

socket.on('respond', function (data) {
  console.log(data);
});

And the messages now appear as frames:

working websockets

This Github issue pointed me in the right direction. Thanks to everyone who helped out!

Answer 3

I had faced same issues, I refined apache2 virtual host entery and got success.

Note: on server I had succesful installed and working on 9001 port without any issue. This guide line for apache2 only no relavence with nginx, this answer for apache2+etherpad lovers.

<VirtualHost *:80>
  ServerName pad.tejastank.com
  ServerAlias pad.tejastank.com
  ServerAdmin [e-mail]

  LoadModule  proxy_module         /usr/lib/apache2/modules/mod_proxy.so
  LoadModule  proxy_http_module    /usr/lib/apache2/modules/mod_proxy_http.so
  LoadModule  headers_module       /usr/lib/apache2/modules/mod_headers.so
  LoadModule  deflate_module       /usr/lib/apache2/modules/mod_deflate.so

  ProxyVia On
  ProxyRequests Off
  ProxyPreserveHost on

    <Location />
        ProxyPass http://localhost:9001/ retry=0 timeout=30
        ProxyPassReverse http://localhost:9001/
    </Location>
    <Location /socket.io>
        # This is needed to handle the websocket transport through the proxy, since
        # etherpad does not use a specific sub-folder, such as /ws/ to handle this kind of traffic.
        # Taken from https://github.com/ether/etherpad-lite/issues/2318#issuecomment-63548542
        # Thanks to beaugunderson for the semantics
        RewriteEngine On
        RewriteCond %{QUERY_STRING} transport=websocket    [NC]
        RewriteRule /(.*) ws://localhost:9001/socket.io/$1 [P,L]
        ProxyPass http://localhost:9001/socket.io retry=0 timeout=30
        ProxyPassReverse http://localhost:9001/socket.io
    </Location>


  <Proxy *>
    Options FollowSymLinks MultiViews
    AllowOverride All
    Order allow,deny
    allow from all
  </Proxy>
</VirtualHost>

Advance tips: Please with help of a2enmod enable all mod of apache2

Restart apache2 than will get effect. But obvious a2ensite to enable site required.

Answer 4

In your controller, you are using an http scheme, but I think you should be using a ws scheme, as you are using websockets. Try to use ws://localhost:3000 in your connect function.

Answer 5

I think you should define your origins for client side as bellow:

//server.js
const socket = require('socket.io');
const app = require('express')();
const server = app.listen('port');

const io = socket().attach(server);
io.origins("your_domain:port www.your_domain:port your_IP:port your_domain:*")

io.on('connection', (socket) => {
  console.log('connected a new client');
});

//client.js
var socket = io('ws://:port');

Answer 6

This worked for me with Nginx, Node server and Angular 4

Edit your nginx web server config file as:

server {
listen 80;
server_name 52.xx.xxx.xx;

location / {
    proxy_set_header   X-Forwarded-For $remote_addr;
    proxy_set_header   Host $http_host;
    proxy_pass         "http://127.0.0.1:4200";
    proxy_http_version 1.1;
    proxy_set_header   Upgrade $http_upgrade;
    proxy_set_header   Connection "upgrade";
}