I need to build twosome chat, using websockets (socket.io + node.js). So, the simple example to broadcast message to all users:
socket.on('user message', function (msg) {
socket.broadcast.emit('user message', socket.nickname, msg);
});
But how can I broadcast it from certain user to certain user?
There are two possibilites :
1) Each socket has its own unique ID stored in socket.id. If you know the ID of both users, then you can simply use
io.sockets[id].emit(...)
2) Define your own ID (for example user's name) and use
socket.join('priv/John');
in connection handler. Now whenever you want send message only to John, you simply do
socket.broadcast.to('priv/John').emit(...)
Side note: the first solution provided cannot be scaled to multiple machines, so I advice using the second one.