When I was looking for samples of WebSocket Server in NodeJS most results where using socket.io. But since I was learning I needed some more basic one. First I thought of using simple net.Socket, later I came to know that its just a TCP socket and WebSocket won’t works with it unless you use websockify to bridge in between.
Then I found ws, a basic WebSocket implementation. So I build a simple websocket server using ws.
// server.js
var Server = require('ws').Server;
var port = process.env.PORT || 9030;
var ws = new Server({port: port});
ws.on('connection', function(w){
w.on('message', function(msg){
console.log('message from client');
});
w.on('close', function() {
console.log('closing connection');
});
});
Now this server can accept connection.
Next we need a client.
var connection = new WebSocket('ws://localhost:9030');
connection.onopen = function () {
};
// Log errors
connection.onerror = function (error) {
console.error('WebSocket Error ' + error);
};
// Log messages from the server
connection.onmessage = function (e) {
};
Now we can send message via WebSocket from server to client and back.
w.on('message', function(msg){
console.log('message from client :: ', msg);
});
w.send('message to client');
And I in client I received it message in onmessage event and from client I can send the message using send method.
// Log messages from the server
connection.onmessage = function (e) {
console.log('message from server', e.data);
};
connection.send('hello from client');
Now when I need to send some message to individual client, I want to keep some reference/indetifier to each client. So I used sec-websocket-key in header. when each client gets connected I keep the object of connection in an array.
var Server = require('ws').Server;
var port = process.env.PORT || 9030;
var ws = new Server({port: port});
var sockets = [];
ws.on('connection', function(w){
var id = w.upgradeReq.headers['sec-websocket-key'];
console.log('New Connection id :: ', id);
w.send(id);
w.on('message', function(msg){
var id = w.upgradeReq.headers['sec-websocket-key'];
var message = JSON.parse(msg);
sockets[message.to].send(message.message);
console.log('Message on :: ', id);
console.log('On message :: ', msg);
});
w.on('close', function() {
var id = w.upgradeReq.headers['sec-websocket-key'];
console.log('Closing :: ', id);
});
sockets[id] = w;
});
And for client I just I send a JSON with info whome this message should be delivered like
var data = {
to: "sec-websocket-identifier",
message: 'hello from client 1'
};
connection.send(JSON.stringify(data));
I think this is the base of 1-1 chat application.