webSocketServer node.js how to differentiate clients

Question

webSocketServer node.js how to differentiate clients

I am trying to use sockets with node.js, I succeded but I don't know how to differentiate clients in my code. The part concerning sockets is this:

var WebSocketServer = require('ws').Server, 
    wss = new WebSocketServer({port: 8080});
wss.on('connection', function(ws) {
    ws.on('message', function(message) {
        console.log('received: %s', message); 
        ws.send(message);
    });
    ws.send('something');
});

This code works fine with my client js.

But I would like to send a message to a particular user or all users having sockets open on my server.

In my case I send a message as a client and I receive a response but the others user show nothing.

I would like for example user1 sends a message to the server via webSocket and I send a notification to user2 who has his socket open.

node.js
websocket

Answer 1

You can simply assign users ID to an array CLIENTS[], this will contain all users. You can directly send message to all users as given below:

var WebSocketServer = require('ws').Server,
    wss = new WebSocketServer({port: 8080}),
    CLIENTS=[];

wss.on('connection', function(ws) {
    CLIENTS.push(ws);
    ws.on('message', function(message) {
        console.log('received: %s', message);
        sendAll(message);
    });
    ws.send("NEW USER JOINED");
});

function sendAll (message) {
    for (var i=0; i<CLIENTS.length; i++) {
        CLIENTS[i].send("Message: " + message);
    }
}

Answer 2

This code snippet in Worlize server really helped me a lot. Even though you're using ws, the code should be easily adaptable. I've selected the important parts here:

// initialization
var connections = {};
var connectionIDCounter = 0;

// when handling a new connection
connection.id = connectionIDCounter ++;
connections[connection.id] = connection;
// in your case you would rewrite these 2 lines as
ws.id = connectionIDCounter ++;
connections[ws.id] = ws;

// when a connection is closed
delete connections[connection.id];
// in your case you would rewrite this line as
delete connections[ws.id];

Now you can easily create a broadcast() and sendToConnectionId() function as shown in the linked code.

Hope that helps.

Answer 3

I'm using fd from the ws object. It should be unique per client.

var clientID = ws._socket._handle.fd;

I get a different number when I open a new browser tab.

The first ws had 11, the next had 12.