I have a nodejs + socket.io solution and sockets join different rooms. How can i select sockets from different rooms to broadcast to them a certain message without using a for loop that will stall the application for all users?
The solution is simple, make every "special" user (the ones that you want to group) connect to a secret channel with Socket.IO, in your server-side code:
var io = require('socket.io').listen(80);
io.sockets.on('connection', function (socket) {
if (condition_to_determine_is_user_has_access) {
socket.join('specials');
socket.broadcast.to('specials').emit("new special user has joined");
}
});
You may also want to block access to that channel to un-allowed users, based on cookies / sessions.
Read more here: http://www.danielbaulig.de/socket-ioexpress/
Related
I'm new to websockets/socket.io/node.js. I'm trying to write a card game app, but pretty much all the example tutorials I've found are creating chat applications. So I'm struggling to get my head around the concepts and how they can be applied to my card game.
Keeping it simple, the card game will involve two players. The game involves moving cards around the table. Each player has to see the other player's moves as they happen (hence the need for constant connections). But the opponents cards are concealed to the other.
So two people browse to the same table then click to sit (and play, when both seats are taken). Using
io.on("connection", function(sock){
//socket events in here
});
am I creating the one socket ('io', or 'sock'?) that both clients and the server share, or is that two separate sockets (server/clientA and sever/clientB)? I ask, because I'm struggling to understand what's happening when a message is emitted and/or broadcast. If a client emits a message, is that message sent to both the server and the other client, or just the server? And then, further does it also send the message to itself as well?? It seems as though that's the logic... or what is the purpose of the 'broadcast' method?
From a functional perspective, I need the server to send different messages to each player. So it's not like a chatroom where the server sends the chat to everyone. But if it's one socket that the three of us share (clients and server), how do I manage who sees what? I've read about namespaces, but I'm struggling to work out how that could be used. And if it's two separate sockets, then I can more easily imagine sending different data to the separate clients. But how is that implemented - is that two 'io' objects, or two 'sock' objects?
Finally, I've got no idea if this is the sort of long-winded question that is accepted here, so if it's not, can someone direct me to a forum that discussions can occur? Cheers!
(in case it matters I'm also using Expressjs as the server).
Edit to add:
Part of my confusion is regarding the difference between 'io' and 'sock'. This code eg from the socket.io page is a good example of methods being applied to either of them:
io.on('connection', function(socket){
socket.emit('request', /* */); // emit an event to the socket
io.emit('broadcast', /* */); // emit an event to all connected sockets
socket.on('reply', function(){ /* */ }); // listen to the event
});
WebSocket server side listens for incoming socket connections from clients.
Each client upon connection opens its own socket between him and server. The server is the one that keeps track of all clients.
So once client emits the message server is listening for, the server can do with that message whatever. The message itself can contain information about who is the recipient of that message.
The server can pass the message to everyone or broadcast it to specific user or users based on information your client has sent you or some other logic.
For a card game:
The server listens for incoming connections. Once two clients are connected both of them should emit game ID in which they want to participate. The server can join their sockets in one game(Room) and all of the communication between those two clients can continue in that room. Each time one of the clients passes data to the server, that data should contain info about the recipient.
Here is one simple example that could maybe get you going:
Client side
// set-up a connection between the client and the server
var socket = io.connect();
// get some game identifier
var game = "thebestgameever";
socket.on('connect', function() {
// Let server know which game you want to play
socket.emit('game', game);
});
function makeAMove(move)
{
socket.emit('madeAMove', {move:move, game:game});
}
socket.on('move', function(data) {
console.log('Player made a move', data);
});
Server side
io = socketio.listen(server);
//listen for new connections from clients
io.sockets.on('connection', function(socket) {
// if client joined game get his socket assigned to the game
socket.on('game', function(game) {
socket.join(game);
});
socket.on('madeAMove', function(data){
let game = data.game;
let move = data.move;
io.sockets.in(game).emit('move', move);
});
})
I am building a complex chatting application, using WebSockets. I use Node.JS's Socket.IO library to implement the protocol. Should I create a separate namespace for each Chat, Or separate room for each Chat?
What is the main difference between Namespaces and Rooms in Socket.IO?
Typically rooms are used if all the clients are of the same type.
Use namespaces if there are different types of clients. For example, anonymous users and authenticated users. In this case one may need to process incoming connection requests differently.
var guest = io.of('/guest');
guest.on('connection', function(socket) {
console.log('A guest client connected');
});
var user = io.of('/user');
user.on('connection', function(socket) {
var authenticated = authenticate(); //authenticate the user
if (!authenticated) {
// log attempt and disconnect the client
}
});
So I'm connecting two variable (objects) to the same socket.io server, one's job is to handle public feed and another's to handle private feed with extended functions.
I've attempted the "force new connection" option, however both connections seem to still use utilize the same socket + session Id.
I originally didn't include code because this is so basic, but here you go:
var socket = io(host);
socket.on('connect', function(e){
socket.emit('join', {
channel: stream_channel,
});
});
One is var socket, the other is var socket2. When it connects to the server it emits "join" where:
io.on('connection', function(socket){
socket.on('join', function(d){
socket.join(d.channel);
});
});
I was able to figure this out by:
Subscribing the websocket to multiple rooms
Appending additional variables at each POST to define the room to emit to
I was able to determine that:
Utilizing the same host will always keep the same session id / socket (even with force connection enabled)
Potentially using a different host or namespace would allow a separation in connection
It's better to keep a single connection with multiple rooms
I want to make a web app where every user can create a chat room that other users can join. I would like to have a main node server managing the rooms, and every time a user creates a new room, a new chat server should be started by the main server and it should manage the room.
My question is, how can I make the new server start in node.js and how can I manage it?
Socket.io allows you too use the room feature and have the behavior you want (separate chat rooms) without running a separate chat server. Running a separate chat server is not really convenient in node.js because it means running another process, and it makes communication between the main server and the chat servers extra complicated.
What i would advise is using that feature and adopt the following kind of design:
io.on('connection', function(socket) {
//initialize the object representing the client
//Your client has not joined a room yet
socket.on('create_room', function(msg) {
//initalize the object representing the room
//Make the client effectively join that room, using socket.join(room_id)
}
socket.on('join_room', function(msg) {
//If the client is currently in a room, leave it using socket.leave(room_id); I am assuming for the sake of simplicity that a user can only be in a single room at all time
//Then join the new room using socket.join(room_id)
}
socket.on('chat_msg', function(msg) {
//Check if the user is in a room
//If so, send his msg to the room only using socket.broadcast.to(room_id); That way, every socket that have joined the room using socket.join(room_id) will get the message
}
}
With this design, you're simply adding listeners to event, and once set up, the whole server is running fine without having to deal with concurrency or sub processes.
It's still very minimalist and you'll probably want to handle a few more concepts, such as unique nicknames, or password authentication etc.
But that can easily be done using this design.
Have fun experimenting with socket.io and node.js!
I'm using Socket.IO in my Node Express app, and using the methods described in this excellent post to relate my socket connections and sessions. In a comment the author describes a way to send messages to a particular user (session) like this:
sio.on('connection', function (socket) {
// do all the session stuff
socket.join(socket.handshake.sessionID);
// socket.io will leave the room upon disconnect
});
app.get('/', function (req, res) {
sio.sockets.in(req.sessionID).send('Man, good to see you back!');
});
Seems like a good idea. However, in my app I will often by sending messages to multiple users at once. I'm wondering about the best way to do this in Socket.IO - essentially I need to send messages to multiple rooms with the best performance possible. Any suggestions?
Two options: use socket.io channels or socket.io namespaces. Both are documented on the socket.io website, but in short:
Using channels:
// all on the server
// on connect or message received
socket.join("channel-name");
socket.broadcast.to("channel-name").emit("message to all other users in channel");
// OR independently
io.sockets.in("channel-name").emit("message to all users in channel");
Using namespaces:
// on the client connect to namespace
io.connect("/chat/channel-name")
// on the server receive connections to namespace as normal
// broadcast to namespace
io.of("/chat/channel-name").emit("message to all users in namespace")
Because socket.io is smart enough to not actually open a second socket for additional namespaces, both methods should be comparable in efficiency.