Express and WebSocket listening on the same port
I have an app.js which is used to trigger two events when some POST data are received:
- Insert POST data into a database
- Send a message to a client using a WebSocket
Here is the app.js (only the important lines)
var express = require('express');
var bodyParser = require('body-parser');
var server = require('./server');
var app = express();
var port = process.env.PORT || 3000;
app.post('/server', server);
app.listen(port, function(){
console.log('Slack bot listening');
});
And here is the server.js (only the important lines)
var db = require('./DB');
var WebSocketServer = require('ws').Server;
var insertData = function(req, res){
var wss = new WebSocketServer({server: server});
console.log('WebSocketServer created');
wss.on('connection', function(wss){
wss.send(JSON.stringify('Socket open'));
});
wss.on('close', function(){
console.log('WebServerSocket has been closed');
});
};
module.exports = insertData;
What I would like to achieve is to set the WebSocketServer in a way that it listen to the same port of the app. I thought about passing the server var from app.js to server.js but
- I think this a not an elegant way to do it
- I don't know how to do it
What do you guys think?
Solution 1:
Based on your code and comments, here's a super simple example of how it would work together.
First, the http-server.js - a typical express app, except that we do not start the server with app.listen():
'use strict';
let fs = require('fs');
let express = require('express');
let app = express();
let bodyParser = require('body-parser');
app.use(bodyParser.json());
// Let's create the regular HTTP request and response
app.get('/', function(req, res) {
console.log('Get index');
fs.createReadStream('./index.html')
.pipe(res);
});
app.post('/', function(req, res) {
let message = req.body.message;
console.log('Regular POST message: ', message);
return res.json({
answer: 42
});
});
module.exports = app;
Now, the ws-server.js example, where we create the WSS server from a node native http.createServer(). Now, note that this is where we import the app, and give this native http.createServer the app instance to use.
Start the app with PORT=8080 node ws-server.js :
(Note you're launching the second, socket related, file (ws-server) not the first, http related, file (http-server).)
'use strict';
let WSServer = require('ws').Server;
let server = require('http').createServer();
let app = require('./http-server');
// Create web socket server on top of a regular http server
let wss = new WSServer({
server: server
});
// Also mount the app here
server.on('request', app);
wss.on('connection', function connection(ws) {
ws.on('message', function incoming(message) {
console.log(`received: ${message}`);
ws.send(JSON.stringify({
answer: 42
}));
});
});
server.listen(process.env.PORT, function() {
console.log(`http/ws server listening on ${process.env.PORT}`);
});
Finally, this sample index.html will work by creating both a POST and a Socket "request" and display the response:
<html>
<head>
<title>WS example</title>
</head>
<body>
<h2>Socket message response: </h2>
<pre id="response"></pre>
<hr/>
<h2>POST message response: </h2>
<pre id="post-response"></pre>
<script>
// Extremely simplified here, no error handling or anything
document.body.onload = function() {
'use strict';
// First the socket requesta
function socketExample() {
console.log('Creating socket');
let socket = new WebSocket('ws://localhost:8080/');
socket.onopen = function() {
console.log('Socket open.');
socket.send(JSON.stringify({message: 'What is the meaning of life, the universe and everything?'}));
console.log('Message sent.')
};
socket.onmessage = function(message) {
console.log('Socket server message', message);
let data = JSON.parse(message.data);
document.getElementById('response').innerHTML = JSON.stringify(data, null, 2);
};
}
// Now the simple POST demo
function postExample() {
console.log('Creating regular POST message');
fetch('/', {
method: 'post',
headers: {
"Content-type": "application/json"
},
body: JSON.stringify({message: 'What is the meaning of post-life, the universe and everything?'})
})
.then(response => response.json())
.then(function (data) {
console.log('POST response:', data);
document.getElementById('post-response').innerHTML = JSON.stringify(data, null, 2);
})
.catch(function (error) {
console.log('Request failed', error);
});
}
// Call them both;
socketExample();
postExample();
}
</script>
</body>
</html>
Note you'll need a quite recent browser, one that has both WebSocket and fetch APIs for this client side part, but it's irrelevant anyway, it just gives you the gist of it.
Solution 2:
http and ws on the same port 80, "Amazing Zlatko Method™."
You'll have a file, say main.js, with
var app = express()
and many lines of express code.
It is perfectly OK to have as much middleware as you want in the usual way with no changes.
var app = express()
app.use(session(session_options))
app.use(passport.initialize())
app.use(passport.session())
app.use('/static', express.static('static'))
// etc etc
app.get ...
app.get ...
app.post ...
app.post ...
Normally at the end of that file you would
app.listen(80, (err) => { ... })
Delete that.
//app.listen(80, (err) => { ... })
No other changes in the express app file.
In your websocket file, say multiplayer.js, you would normally have
const WebSocket = require('ws');
const wss = new WebSocket.Server({
port: 9999,
perMessageDeflate: false
})
In fact, change to
const WebSocket = require('ws');
/*const wss = new WebSocket.Server({
port: 2828,
perMessageDeflate: false
});*/
let WSServer = WebSocket.Server;
let server = require('http').createServer();
let app = require('./main'); // note, that's your main.js file above
let wss = new WSServer({
server: server,
perMessageDeflate: false
})
server.on('request', app);
TBC, note that, surprisingly to me, WebSocket.Server does indeed naturally want to listen on 80.
And at the end of that file
server.listen(80, function() {
console.log(`Amazing Zlatko Method™ combo server on 80`);
});
Note! - launch the 'multiplayer.js' file (not 'main.js').
It works perfectly. Amazing stuff.