Environment:
Backend
node:latest
socket.io | 4.5.2
Frontend
React Native | 0.70.4
socket.io-client | 4.6.0
both Android and iOS
Here is my NodeJs entry file:
const numCPUs = cpus().length
if (cluster.isPrimary) {
const app = express()
const httpServer = http.createServer(app)
setupMaster(httpServer, { loadBalancingMethod: 'least-connection' })
setupPrimary()
for (let i = 0; i < numCPUs; i++) {
cluster.fork()
}
cluster.on('exit', (worker) => {
cluster.fork()
})
} else {
const app = express()
const httpServer = http.createServer(app)
const io = new Server(httpServer, { maxHttpBufferSize: 1e8 })
io.adapter(createAdapter())
setupWorker(io)
API.Socket.init(io, process.pid)
middlewares.forEach((middleware: any) => app.use(middleware))
routes.forEach((route) => app.use(route.path, route.handler))
httpServer.listen(CONFIG.PORT, () => {})
}
I have a simple chat application.
When user A sends message to user B, new chat message and notification is recorded in database. Now that chat message and notification* should be sent to the B user. There are 2 socket emit-functions for that:
sendNewNotification(
notification: BE.Entities.TNotification,
toUser: string,
) {
this.io
?.to(toUser)
.volatile.emit(ECustomEvents.NewNotification, notification)
}
sendPrivateMessage(
toUser: string | Array<string>,
chatMessage: BE.Entities.TChatMessage,
sourceUser: BE.Entities.TUser,
) {
this.io
?.to(toUser)
.volatile.emit(ECustomEvents.PrivateMessage, chatMessage, sourceUser)
}
If I do it like this, the targetUser is not going to receive the event with the newChatMessage however he will receive the savedNotification
API.Socket.sendPrivateMessage(targetUserId, newChatMessage, userToPass)
API.Socket.sendNewNotification(savedNotification, targetUserId)
Now, if I switch these lines:
API.Socket.sendNewNotification(savedNotification, targetUserId)
API.Socket.sendPrivateMessage(targetUserId, newChatMessage, userToPass)
the behavior would be as expected: the target user B will receive both saved notification and new chat message
How is that possible? What could be wrong?
Thank you mates in advance!
With the current information, I'm not so sure the order matters but perhaps that it's a side-effect / coincidence. Are you checking anywhere to make sure the server-side socket is ready before the client emits?
Consider this super simple WebSocket chat sandbox:
One of the issues I noticed when writing this is when the server WebSocket is not ready, I could not emit from the client to the server. To make sure the server is ready, I sent a ping from the server to the client notifying the client that the server is ready:
wss.on("connection", async function connection(client, request) {
console.log("user connected", Date.now());
client.send(JSON.stringify({ ready: true }));
...
});
I also notice you are usingg the volatile.emit which according to the documentation:
Volatile events
Volatile events are events that will not be sent if the underlying connection is not ready (a bit like UDP, in terms of reliability).
This can be interesting for example if you need to send the position of the characters in an online game (as only the latest values are useful).
socket.volatile.emit("hello", "might or might not be received");
The Socket.IO docs have a similar listener which lets you know when the server is ready.
If you prevent the client from emitting until the server is ready, you can avoid this issue. You also should not need to use the volatile.emit for something that must be delivered.
Related
So i've been making a realtime E2EE chatting application in node.js and socket.io, and I've ran into an issue
I'm using a recent socket.io version, specifically 4.2.0 and I've been attempting to find out the number of clients within a room, in order to create a check to either allow, or block access to a chat area, since it doesn't support more than 2 clients in 1 room.
My variables/includes for socket.io
var socket = require("socket.io")
var io = socket(server)
var chat = io.of('/socket').on('connection', function (socket) {
socket.on('loginchat', async function(data){
io.in(data.id).allSockets().then(result=>{
console.log(result.size) })
});
});
data.id is a randomly generated string and used to create a room server side, so my idea was to use allSockets() to get a count of sockets connected to that room, but it returns zero even with 2 clients connected.
allSockets() idea from https://stackoverflow.com/a/66065685/16140221
I can't find a working solution on stack overflow, or anything inside the docs that is an obvious method to do so. I'm not the best at socket.io since I simply picked it up to use for this project, so any help is appreciated :)
Given the example you provided, you don't seem to ever make a socket to join a room. So your room is forever empty.
According the socket.io documentation you must first listen for the connection event, then you must use join to add users to the room.
const socket = require("socket.io")
const io = socket(server)
io.on("connection", socket => {
socket.on('loginchat', async data => {
//Assuming data.id is the room identifier
const roomUsers = await io.in(data.id).allSockets();
//There, you make your socket join the room if room users are not exceeding
//your maximum
if(roomUsers.size < 2) socket.join(data.id);
});
});
var socket = require("socket.io")
var io = socket(server)
var chat = io.of('/socket').on('connection', function (socket) {
socket.on('loginchat', async function(data){
const sockets = await io.of("/socket").in(data.id).fetchSockets();
console.log(sockets.length)
if(sockets.length <= 1){
socket.room = data.id;
socket.join(data.id);
}else{
//attempting to join a room with greater than 2 users
console.log("too many")
}
});
});
https://socket.io/docs/v3/migrating-from-3-x-to-4-0/
Using the fetchSockets() and checking the length of the object, you are able to check the length or numbers of users in a room.
Working in Socket.io v4.3.1 but most likely functioning in any v4.x
I am working on Socket IO, the connection between the client and the server is established successfully. I am facing two problems:
1 - When the initial connection is made between the client and the server, the socket.client.id on server and socket.id on client side, both are the same, but when I refresh the client page, the id of the client changes to other one, but on the server it is still the same. Does it makes any issue / problem while communicating with the server or even with the client using sockets, while not having the same ids ? or does the id on the server get changed when the client page is refreshed ?
2 - On the initial connection establishment the socket passes a messages, using socket.emit() from server and receives as socket.on() on client. But when I try to emit anything from client it doesn't get received on server.
Socket Connections
function Globals() {
this.socketConnection = async function() {
let p = new Promise(function(res, rej) {
io.on("connection", function(socket) {
if (socket.connected) {
res(socket);
} else {
rej("Socket Connection Error !");
}
})
})
return await p;
}
}
new Globals().socketConnection().then(function(soc) {
console.log(soc.client.id);
socket = soc;
soc.emit("Hi");
soc.on("Nady", function() {
console.log("I am called");
})
})
Client Side Connection
function Globals() {
this.socketConnection = async function() {
var socket = io('http://localhost:8080');
let p = new Promise(function(res, rej) {
socket.on('connect', function() {
if (socket.connected) {
console.log(socket.id);
res(socket);
}
})
})
return await p;
}
}
var socket;
new App().socketConnection().then(function(s) {
socket = s;
});
function ScrapJobs() {
var socket;
new App().socketConnection().then(function(s) {
socket = s;
});
var _this = this;
this.attachListeners = function() {
qs("#init-scrap").ev("click", _this.startScrapping);
}
this.startScrapping = function() {
console.log("I am cliced");
socket.on("Hi", function() {
console.log("Hi Nadeem");
})
socket.emit("Nady");
}
}
When the initial connection is made between the client and the server, the socket.client.id on server and socket.id on client side, both are the same, but when I refresh the client page, the id of the client changes to other one, but on the server it is still the same. Does it makes any issue
The client side socket.id value is set on the client socket object after the connect event is received and is updated (e.g. modified) upon a reconnect event.
It appears that the socket.io infrastructure will keep them the same on client and server. If the client disconnects and then reconnects, there will be a new connection with a new id on both client and server. It is possible you are attempting to hang onto the old socket object on the server after the client has disconnected it (we can't really see enough of your server code to evaluate that).
On the initial connection establishment the socket passes a messages, using socket.emit() from server and receives as socket.on() on client. But when I try to emit anything from client it doesn't get received on server.
You'd have to show us a reproducible case. This does not happen if you are coding things correctly. I would guess that you do not have the right listeners for messages on the right socket in order to see the messages you are sending. I promise you that sending a message from client to server works just fine when implemented properly.
A general comment about your code. Both code blocks you show appear to be stuffing a socket object into a higher scoped (or perhaps even global) variable. That is likely part the cause of your problem because that socket object can become dead if the client reconnects for any reason. Plus putting any sort of socket object into a global or module level variable makes your server only capable of serving one client - it's simply not how you design multi-client servers.
I'm exploring different websocket library for self-learning and I found that this library is really amazing ws-node. I'm building a basic 1 on 1 chat in ws-node library
My question is what is the equivalent of socket.io function which is socket.to().emit() in ws? because i want to send a message to a specific user.
Frontend - socket.io
socket.emit("message", { message: "my name is dragon", userID: "123"});
Serverside - socket.io
// listening on Message sent by users
socket.on("message", (data) => {
// Send to a specific user for 1 on 1 chat
socket.to(data.userID).emit(data.message);
});
WS - backend
const express = require('express');
const http = require('http');
const WebSocket = require('ws');
const express = require('express');
const http = require('http');
const WebSocket = require('ws');
const app = express();
const server = http.createServer(app);
const wss = new WebSocket.Server({ server });
wss.on('connection', (ws) => {
ws.on('message', (data) => {
\\ I can't give it a extra parameter so that I can listen on the client side, and how do I send to a specific user?
ws.send(`Hello, you sent -> ${data.message}`);
});
});
Honestly, the best approach is to abstract away the WebSocket using a pub/sub service.
The issue with client<=(server)=>client communication using WebSockets is that client connections are specific to the process (and machine) that "owns" the connection.
The moment your application expands beyond a single process (i.e., due to horizontal scaling requirements), the WebSocket "collection" becomes irrelevant at best. The array / dictionary in which you stored all your WebSocket connections now only stores some of the connections.
To correct approach would be to use a pub/sub approach, perhaps using something similar to Redis.
This allows every User to "subscribe" to a private "channel" (or "subject"). Users can subscribe to more than one "channel" (for example, a global notification channel).
To send a private message, another user "publishes" to that private "channel" - and that's it.
The pub/sub service routes the messages from the "channels" to the correct subscribers - even if they don't share the same process or the same machine.
This allows a client connected to your server in Germany to send a private message to a client connected to your server in Oregon (USA) without anyone being worried about the identity of the server / process that "owns" the connection.
There isn't an equivalent method. socket.io comes with a lot of helpers and functionalities, that will make your life easier, such as rooms, events...
socket.io is a realtime application framework, while ws is just a WebSocket client.
You will need to make your custom wrapper:
const sockets = {};
function to(user, data) {
if(sockets[user] && sockets[user].readyState === WebSocket.OPEN)
sockets[user].send(data);
}
wss.on('connection', (ws) => {
const userId = getUserIdSomehow(ws);
sockets[userId] = ws;
ws.on('message', function incoming(message) {
// Or get user in here
});
ws.on('close', function incoming(message) {
delete sockets[userId];
});
});
And then use it like this:
to('userId', 'some data');
In my opinion, if you seek that functionality, you should use socket.io. Which it's easy to integrate, has a lot of support, and have client libraries for multiple languages.
If your front-end uses socket.io you must use it on the server too.
Question based on this answer: https://stackoverflow.com/a/18650183/4478897
I tried to find this solution but nothing seems to work in the way that I need.
Clustering expressjs and socket.io we can share sessions using redis and send io messages inside io world (io.sockets.on('connection',...). The problem is if we want to send the message (or use a simple socket.join/leave) inside the expressjs world (route.get/post).
If we are not using clusters we can atach the client socket object to the express request object (or simply export the io object) and then use it at any time on any GET/POST route.
At the other hand, if we are clustering and use the mentioned method to get the socket object inside the expressjs world, sometimes the socket object is undefined because the socket object for this client is initialized at other worker.
Some example flow:
Client connects to http://localhost and worker 1 handles this request.
After the page is loaded, the client connects to socket.io. Worker 2 handles this connection.
Client do a POST and again worker 1 or worker X handles this request.
In this case when the client do the POST, only the worker 2 knows the socket object for this client. So this will get an undefined socket object.
So, the question:
How can we get the client socket object from any worker to reuse it on expressjs request object.
Maybe my code is wrong but is almost like the link to the answer mentioned above.
NOTEs
Don't want to use some kind of proxy.
Don't want to migrate to other libraries (expressio, sockjs...)
Sorry for my English :)
Using last nodejs, socket.io, expressjs, socket.io-redis, redis... versions
Don't hesitate to ask something!
UPDATE 1
Possible solution but still need to test it. Dont know if this is a really good: solution.
UPDATE 3: Working code on my own answer
UPDATE 2
Like update 1 but using https://nodejs.org/dist/latest-v5.x/docs/api/cluster.html#cluster_event_message
remoteJoin and remoteLeave methods were added in socket.io-redis 3.0.0:
io.adapter.remoteJoin('<my-id>', 'room1', function (err) {
if (err) { /* unknown id */ }
// success
});
io.adapter.remoteLeave('<my-id>', 'room1', function (err) {
if (err) { /* unknown id */ }
// success
});
Note: The implementation looks a lot (hopefully?) like the answer above.
Well finally tried the code and it works (with some misspells modifications and other things) but i'm sure that needs to be a better code somewhere. So i'm open to more answers!
This code is part of my socket.io module when authorize the client socket and some other stuff...
var redis = require("redis");
var redisPub = redis.createClient();
var redisSub = redis.createClient();
var PubSubChannel = "clusterChannel";
// Function that checks if this worker knows the socket object of this socketId.
// If not, publish the message to all the other sockets (workers)
io.socketDo = function (type, socketId, roomName) {
if (typeof io.sockets.connected[socketId] != "undefined") {
if (type === "join") {
return io.sockets.connected[socketId].join(roomName);
}
if (type === "leave") {
return io.sockets.connected[socketId].leave(roomName);
}
} else {
redisPub.publish(
PubSubChannel,
JSON.stringify({
type: type,
socketId: '' + socketId,
roomName: roomName
})
);
}
};
// Subscribe to some channel
redisSub.subscribe(PubSubChannel);
// When this worker receive a message from channel "PubSubChannel" checks
// if it have the socket object for this socketId and do the operation
redisSub.on("message", function (channel, data) {
data = JSON.parse(data);
var type = data.type;
var socketId = data.socketId;
var roomName = data.roomName;
if ((type === "join" || type === "leave") && channel == PubSubChannel){
if (typeof io.sockets.connected[socketId] != "undefined") {
if (type === "join") {
return io.sockets.connected[socketId].join(roomName);
}
if (type === "leave") {
return io.sockets.connected[socketId].leave(roomName);
}
}
}
});
Then just simply export the module and attach it to your expressjs request => req.io = io
// req.session.socketId value is fetched on "io.sockets.on('connection', function(socket) {"
// by express to socket.io using redis shared sessions
app.get('/', function (req, res) {
req.io.socketDo('join', req.session.socketId, 'someRoomToJoin');
// IT WORKS!
req.io.sockets.in('someRoomToJoin').emit('text');
req.io.socketDo('leave', req.session.socketId, 'someRoomToLeave');
res.send('Hello World!');
});
In my normal setup, the client will emit data to my server regardless of whether or not there is another client to receive it. How can I make it so that it only sends packets when the user-count is > 1? I'm using node with socket.io.
To do this you would want to listen to the connection event on your server (as well as disconnect) and maintain a list of clients which are connected in a 'global' variable. When more than 1 client is connected send out a message to all connected clients to know they can start sending messages, like so:
var app = require('express').createServer(),
io = require('socket.io').listen(app);
app.listen(80);
//setup express
var clients = [];
io.sockets.on('connection', function (socket) {
clients.push(socket);
if (clients.length > 1) {
io.socket.emit('start talking');
}
socket.on('disconnect', function () {
var index = clients.indexOf(socket);
clients = clients.slice(0, index).concat(clients.slice(index + 1));
if (clients.length <= 1) {
io.sockets.emit('quiet time');
};
});
});
Note: I'm making an assumption here that the socket is passed to the disconnect event, I'm pretty sure it is but haven't had a chance to test.
The disconnect event wont receive the socket passed into it but because the event handler is registered within the closure scope of the initial connection you will have access to it.