I take a few step into socket.io. It's very hard to code without req, because I don't know response to who.
For this question. My website have some blogs. When the blogs updated , I need to 'tell' users who followed the blogs that the blogs have been updated. The problems are I don't know witch followed users are online and I don't know how to emit events to them with only followed user id.
Can some one give me some tips? No need any specific code.
You can call join to subscribe the socket to a given channel:
io.on('connection', function(socket){
socket.join('some room');
});
And then simply use to when broadcasting or emitting:
io.to('some room').emit('some event');
To leave a channel, you need to call leave :
io.on('disconnect', function(socket){
socket.leave('some room');
});
You can make use of cookies to map http requests to corresponding socket connection. Lets say we are using cookie sesson-id.
Drop this cookie on client on a http request.
In the following patch of code, before creating a new socket connection, you attach session-id cookie to the socket header. This way you can access this session-id in .on("connection") event:
var io = require("socket.io");
sio = io.listen(server);
sio.set("authorization", function (data, accept) {
if (data.headers.cookie) {
data.cookie = cookie.parse(data.headers.cookie);
data.headers.sessionID = data.cookie["session-id"];
}
accept(null, true);
});
Next, you store socket connection objects associated to their session-id:
var sockets = {}; // store all socket connections here
sio.sockets.on("connection",connected);
function connected(socket){
var sessionID = socket.handshake.headers.sessionID;
sockets[sessionID] = socket;
}
Now, whenever you wish to emit socket event related to a particular http request:
function dummyReq(req,res){
var session_id = // get cookie from req
//after certain actions
sockets[session_id].emit("dummy-event","dummy-message");
}
In your case you will have to emit socket events for all session-id linked to users who are following those blogs
Related
I've started writing a node.js websocket solution using socket.io.
The browsers connects to the node server successfully and I get see the socket.id and all config associated with console.log(socket). I also pass a userid back with the initial connection and can see this on the server side to.
Question: I'm not sure the best way to associate a user with a connection. I can see the socket.id changes every page change and when a tab is opened up. How can I track a user and send 'a message' to all required sockets. (Could be one page or could be 3 tabs etc).
I tried to have a look at 'express-socket.io-session' but I'm unsure how to code for it and this situation.
Question: I have 'io' and 'app' variables below. Is it possible to use the 2 together? app.use(io);
Essentially I want to be able to track users (I guess by session - but unsure of how to handle different socket id's for tabs etc) and know how to reply to user or one or more sockets.
thankyou
The best way to handle the situation is rely on SocketIO's rooms. Name the room after the user's unique ID. This will support multiple connections out of the box. Then, whenever you need to communicate with a particular user, simply call the message function and pass in their id, the event, and any relevant data. You don't need to worry about explicitly leaving a room, SocketIO does that for you whenever their session times out or they close their browser tab. (We do explicitly leave a room whenever they log out though obviously)
On the server:
var express = require('express');
var socketio = require('socket.io');
var app = express();
var server = http.createServer(app);
var io = socketio(server);
io.on('connect', function (socket) {
socket.on('userConnected', socket.join); // Client sends userId
socket.on('userDisconnected', socket.leave); // Cliend sends userId
});
// Export this function to be used throughout the server
function message (userId, event, data) {
io.sockets.to(userId).emit(event, data);
}
On the client:
var socket = io('http://localhost:9000'); // Server endpoint
socket.on('connect', connectUser);
socket.on('message', function (data) {
console.log(data);
});
// Call whenever a user logs in or is already authenticated
function connectUser () {
var userId = ... // Retrieve userId somehow
if (!userId) return;
socket.emit('userConnected', userId);
}
// Call whenever a user disconnects
function disconnectUser () {
var userId = ... // Retrieve userId somehow
if (!userId) return;
socket.emit('userDisconnected', userId);
}
I am trying to reconnecct the socket after the disconnect event is fired with same socket.id here is my socket config
var http = require('http').Server(app);
var io = require('socket.io')(http);
var connect_clients = [] //here would be the list of socket.id of connected users
http.listen(3000, function () {
console.log('listening on *:3000');
});
So on disconnect event i want to reconnect the disconnected user with same socket.id if possible
socket.on('disconnect',function(){
var disconnect_id = socket.id; //i want reconnect the users here
});
By default, Socket.IO does not have a server-side logic for reconnecting. Which means each time a client wants to connect, a new socket object is created, thus it has a new id. It's up to you to implement reconnection.
In order to do so, you will need a way to store something for this user. If you have any kind of authentication (passport for example) - using socket.request you will have the initial HTTP request fired before the upgrade happened. So from there, you can have all kind of cookies and data already stored.
If you don't want to store anything in cookies, the easiest thing to do is send back to client specific information about himself, on connect. Then, when user tries to reconnect, send this information again. Something like:
var client2socket = {};
io.on('connect', function(socket) {
var uid = Math.random(); // some really unique id :)
client2socket[uid] = socket;
socket.on('authenticate', function(userID) {
delete client2socket[uid]; // remove the "new" socket
client2socket[userID] = socket; // replace "old" socket
});
});
Keep in mind this is just a sample and you need to implement something a little bit better :) Maybe send the information as a request param, or store it another way - whatever works for you.
How can one use an Express POST request as the basis for a socket.io broadcast (instead of a socket message)?
var app = express();
var server = require('http').createServer(app);
var io = require('socket.io')(server);
app.post('/campaigns', function(req, res, next) {
var campaign = new Campaign(req.body);
campaign.save(function(err, campaign) {
if (err) {
next(err);
} else {
res.json(campaign);
// how to broadcast a message to everyone
// except the sender of this POST request?
io.of('/campaigns').emit('new', campaign);
}
});
});
Very simple.
Each time you establish a connection to server, your socket object will have id associated with this connection. Save it on client side in some variable.
Then each time you post a request to server add socket id to query parameters. Upon receiving POST request on server side broadcast the message to all users and socket id to message. On client side modify on message event by adding a logic to skip/hide received message if client's socket id is equal to socket id received as a extra parameter in message.
Pitfalls
May not work if for some reason after POST request client was disconnected and reconnected to server - in this case upon receiving a message back client will have new socket id that is different from what it had before sending POST request. In that case you will have to come up with some more connection-independent client ID scheme to identify client and use it instead of socket.id as identifier. You may try to use sessions.
Client will still receive message even if it won't be displayed.
Not good to combine client-server "intercommunication" methods and use one from another and vice versa.
Now, after some hours of playing around with nodejs and socket.io, I'm getting a couple more problems - one being, that I need to get the sessionID inside node.js, whitout using app.get('/' ... - since that event doesnt seem to fire when socket.io connects, it only fires .on('connection', function( ...
var express = require('express')()
express.set('port', process.env.PORT || 8080)
var server = require('http').createServer(express)
var socket = require('socket.io').listen(server)
server.listen(express.get('port'))
// this event is fired, get('/', ... isnt!
server.on('connection', function(stream) {
// ??
} )
The Session is initially created by the PHP application, as the user logs in. Session data is stored in the database, and the key I need to access that data is the SESSION ID. What's the easiest way to get to it? Like mentioned, I found a couple examples that used app.get('/' ... but I couldnt get that event to fire at all.
Thanks.
If the session data is being stored as a cookie (most likely), then you should be able to re-parse that data during the socket handshake. I posted code for that on this answer, but copied the code here as well:
io.configure(function () {
io.set('authorization', function (handshakeData, callback) {
var cookie = handshakeData.headers.cookie;
// parse the cookie to get user data...
// second argument to the callback decides whether to authorize the client
callback(null, true);
});
});
If the session data is being propagated in the URL, then you may be able to gather this information from handshakeData.url or handshakeData.query. You'll probably have to do your own experimentation.
Hello I am trying to build chat into an application. What I am wondering is when the user logs out of the website how do I also destroy the socket.io handshake associated with that session so the user cannot send messages from say another tab when he is logged out.
I am using expressjs if that is any help.
Well in case anyone ever find this and wants to know I did figure it out.
You can access the sockets disconnect function. I had object of users ids and their socket id so when someone logged out I called
app.get("/logout", function(req,res){
//do other logging out stuff
sockets.disconnectUser(req.session.user_id);
}
// Disconnect User function
sockets.disconnectUser = function(user_id){
sockets.socket(users[user_id]).disconnect();
}
The socket.io object contains information about all connected sockets and the sessionID of each socket. Thus, it is possible to iterate through the connected sockets and disconnect those which are associated with the sessionID that is logging out. There is no need to manually track user and socket ids in this approach.
Example code tested with socket.io#2.2.0, express#4.17.1 and express-session#1.16.2.
const SocketIO = require('socket.io');
let sio = new SocketIO;
app.get('/logout', function(req, res) {
//do other logging out stuff
logoutSocketsIO(req.sessionID);
});
// Iterate through all connected sockets and close those which are associated
// with the given sessionID
// Note: One sessionID can have multiple sockets (e.g. many browser tabs)
function logoutSocketsIO(sessionID) {
let connections = sio.sockets.connected;
for(let c in connections) {
let socketSessionID = connections[c].conn.request.sessionID;
if(sessionID === socketSessionID) {
connections[c].disconnect();
}
}
}