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Why my socketio is not connecting with my socketio-client?

i am working on a chatapp project that needs a real time chatting so i have used socketio in my server side which is written in nodejs and than used socketio-client in my main chatapp react-native project.
But now a problem is coming my socket is not initializing. I'm not able to connect my server with my main app. I am using socketio and socketio client my both the socket version are same 4.5.1 but it's not even connecting. I have tried to use old version of socket but its also not working and I have also tried to change my localhost port to 4000 but it's also not working.
My server code:
const express = require('express');
var bodyParser = require('body-parser');
const app = express();
const http = require('http');
const server = http.createServer(app);
const { Server } = require("socket.io");
const io = new Server(server);
const port = process.env.PORT || 3000;
require('./src/config/database')
const user_routes = require('./src/user/users.routes');
app.use(bodyParser.urlencoded({extended: true}))
app.use(express.json())
app.get('/', (req, res) => {
res.sendFile(__dirname + '/index.html');
});
app.use('/User', user_routes)
io.on('connection', (socket) => {
console.log('a user connected');
socket.on('send_message',(data)=>{
console.log("received message in server side",data)
io.emit('received_message',data)
})
socket.on('disconnect', () => {
console.log('user disconnected');
});
});
server.listen(port, () => {
console.log( `Server running at http://localhost:${port}/`);
});
My app socketservice file code:
import io from 'socket.io-client';
const SOCKET_URL = 'http://localhost:3000'
class WSService {
initializeSocket = async () => {
try {
this.socket = io(SOCKET_URL, {
transports: ['websocket']
})
console.log("initializing socket", this.socket)
this.socket.on('connect', (data) => {
console.log("=== socket connected ====")
})
this.socket.on('disconnect', (data) => {
console.log("=== socket disconnected ====")
})
this.socket.on('error', (data) => {
console.log("socekt error", data)
})
} catch (error) {
console.log("scoket is not inialized", error)
}
}
emit(event, data = {}) {
this.socket.emit(event, data)
}
on(event, cb) {
this.socket.on(event, cb)
}
removeListener(listenerName) {
this.socket.removeListener(listenerName)
}
}
const socketServcies = new WSService()
export default socketServcies
Where I have marked it should be connected = true but it's false in the dev console I have done console log so check that it's connecting or not and I can see that it's not connecting. How to make it connect?
There is no error in my app or server I have checked many times and my server is also running when I am running my app.

Answering my own question
The problem was i was using android emulator and android in an emulator can't connect to localhost you need to use the proxy ip so when i add http://10.0.2.2:3000 in const SOCKET_URL = 'http://10.0.2.2:3000' than its working fine
credit goes to gorbypark who told me this in discord

I'm assuming that your front and back runs in localhost. The documentation says that if the front-end is in the same domain as the back-end, you don't need to use the URL. Since you have the options parameter declared, you can use the default argument window.location in first place:
class WSService {
initializeSocket = async () => {
try {
this.socket = io(window.location, {
transports: ['websocket']
})
console.log("initializing socket", this.socket)
this.socket.on('connect', (data) => {
console.log("=== socket connected ====")
})
this.socket.on('disconnect', (data) => {
console.log("=== socket disconnected ====")
})
this.socket.on('error', (data) => {
console.log("socekt error", data)
})
} catch (error) {
console.log("scoket is not inialized", error)
}
}
emit(event, data = {}) {
this.socket.emit(event, data)
}
on(event, cb) {
this.socket.on(event, cb)
}
removeListener(listenerName) {
this.socket.removeListener(listenerName)
}
}

Don't specify the host/port for socket-io to connect to. It can figure it out on its own.
Per documentation, it tries to connect to window.location if no URL is specified as an argument.
So instead of
this.socket = io(SOCKET_URL, {
transports: ['websocket']
})
Just do
this.socket = io()
I am not sure it works with other arguments. You could try like this
this.socket = io(undefined, {
transports: ['websocket']
})

WebSocket connection is taking long time and failed

I created a secure websocket using this,
const Socket = require("websocket").server
const https = require("tls")
const fs = require('fs');
//certificate information
const certificate = {
cert: fs.readFileSync("/home/WebRTC/ssl/webrtc.crt",'utf8'),
key: fs.readFileSync("/home/WebRTC/ssl/webrtc.key",'utf8')
};
const server = https.createServer(certificate,(req, res) => {})
server.listen(3000, () => {
console.log("Listening on port 3000...")
})
const webSocket = new Socket({ httpServer: server })
and created the web client using this,
const webSocket = new WebSocket("wss://ip:3000")
webSocket.onerror= (event) => {
alert("Connection error occured");
}
webSocket.onopen = (event) =>{
alert("Connection established");
}
webSocket.onmessage = (event) => {
alert("Message received");
}
Im using https. Created a self signed certificate
wss://ip:3000. here the IP is the certificate resolving IP. These files are hosted in a publicly accessible server
But when I put the request, it takes a lot of time and gives and error.
"WebSocket connection to 'wss://ip:3000/' failed: "
Please be kind enough to help

NextJS, Express, Error during WebSocket handshake: Unexpected response code: 200

The basic problem can be summarized as follows: When creating a Websocket server in Node using ws with the server option populated by an express server(as in this example), while using that same express server to handle the routing for NextJS (as in this example), the upgrade header seems to not be properly parsed.
Instead of the request being routed to the Websocket server, express sends back an HTTP 200 OK response.
I've searched high and low for an answer to this, it may be that I simply do not understand the problem. A possibly related question was brought up in an issue on NextJS's github. They recommend setting WebsocketPort and WebsocketProxyPort options in the local next.config.js, however I have tried this to no avail.
A minimal example of the relevant server code can be found below. You may find the full example here.
const express = require('express')
const next = require('next')
const SocketServer = require('ws').Server;
const port = parseInt(process.env.PORT, 10) || 3000
const dev = process.env.NODE_ENV !== 'production'
const app = next({ dev })
const handle = app.getRequestHandler()
app.prepare().then(() => {
const server = express()
server.all('*', (req, res) => {
return handle(req, res)
})
server.listen(port, err => {
if (err) throw err
console.log(`> Ready on http://localhost:${port}`)
})
const wss = new SocketServer({ server });
wss.on('connection', function connection(ws, request) {
console.log('Client connected');
ws.on('close', () => console.log('Client disconnected'));
});
wss.on('error', function (error) {
console.log(error);
});
setInterval(() => {
wss.clients.forEach((client) => {
client.send(new Date().toTimeString());
});
}, 1000);
}).catch(ex => {
console.error(ex.stack);
process.exit(1);
});
The expected result, of course, is a connection to the websocket server. Instead I receive the following error:
WebSocket connection to 'ws://localhost:3000/' failed: Error during WebSocket handshake: Unexpected response code: 200
Can anyone elucidate anything for me here?

Ok, after more digging I have solved the problem. Quite simply, the ws.Server object to which I was trying to feed the server = express() object is not strictly speaking an http server object. However, server.listen() returns such an http server object. On such an object we can listen for an 'upgrade' call, which we can pass to our ws.Server object's handleUpgrade() event listener, through which we can connect. I will be updating the examples that I linked in my question, but the relevant code is below:
app.prepare().then(() => {
const server = express()
server.all('*', (req, res) => {
return handle(req, res)
})
const wss = new SocketServer({ server });
wss.on('connection', function connection(ws, request) {
console.log('Client connected');
ws.on('close', () => console.log('Client disconnected'));
});
wss.on('error', function (error) {
console.log(error);
});
let srv = server.listen(port, err => {
if (err) throw err
console.log(`> Ready on http://localhost:${port}`)
})
srv.on('upgrade', function(req, socket, head) {
wss.handleUpgrade(req, socket, head, function connected(ws) {
wss.emit('connection', ws, req);
})
});

Socket.IO server to server connection doesn't work

I wrote a simple test case.
const socketioclient = require("socket.io-client");
const io = require("socket.io");
const server = io.listen(process.env.PORT);
server.on("connection", (client) => {
console.log("[SERVER] Client connected!");
client.emit("chat", "Bye!");
client.on("bye", () => {
console.log("[SERVER] Client goodbye'd us.");
client.disconnect();
})
});
const client = socketioclient("localhost:" + process.env.PORT);
client.once("connect", () => {
console.log("[CLIENT] Connected to remote server, identificating.")
this.sendIdentification();
});
client.on("chat", (msg) => {
console.log("[CLIENT] Server sends message:", msg);
if (msg.toLowerCase().indexOf("bye") != -1) {
client.emit("bye");
}
});
client.on("disconnected", () => {
console.log("[CLIENT] Disconnected.");
})
client.on("error", () => {
console.error("[CLIENT] Socket IO connection error.")
});
If you run it, nothing happens. Client does not connect to the server at all.

How to send broadcast to all connected client in node js

I'm a newbie working with an application with MEAN stack. It is an IoT based application and using nodejs as a backend.
I have a scenario in which I have to send a broadcast to each connected clients which can only open the Socket and can wait for any incoming data. unless like a web-browser they can not perform any event and till now I have already gone through the Socket.IO and Express.IO but couldn't find anything which can be helpful to achieve what I want send raw data to open socket connections'
Is there any other Node module to achieve this. ?
Here is the code using WebSocketServer,
const express = require('express');
const http = require('http');
const url = require('url');
const WebSocket = require('ws');
const app = express();
app.use(function (req, res) {
res.send({ msg: "hello" });
});
const server = http.createServer(app);
const wss = new WebSocket.Server({ server });
wss.on('connection', function connection(ws) {
ws.on('message', function(message) {
wss.broadcast(message);
}
}
wss.broadcast = function broadcast(msg) {
console.log(msg);
wss.clients.forEach(function each(client) {
client.send(msg);
});
};
server.listen(8080, function listening() {
console.log('Listening on %d', server.address().port);
});
Now, my query is when this code will be executed,
wss.on('connection', function connection(ws) {
ws.on('message', function(message) {
wss.broadcast(message);
}
}

var WebSocketServer = require("ws").Server;
var wss = new WebSocketServer({port:8100});
wss.on('connection', function connection(ws) {
ws.on('message', function(message) {
wss.broadcast(message);
}
}
wss.broadcast = function broadcast(msg) {
console.log(msg);
wss.clients.forEach(function each(client) {
client.send(msg);
});
};

Try the following code to broadcast message from server to every client.
wss.clients.forEach(function(client) {
client.send(data.toString());
});
Demo server code,
const WebSocket = require('ws')
const wss = new WebSocket.Server({ port: 2055 },()=>{
console.log('server started')
})
wss.on('connection', (ws) => {
ws.on('message', (data) => {
console.log('data received \n '+ data)
wss.clients.forEach(function(client) {
client.send(data.toString());
});
})
})
wss.on('listening',()=>{
console.log('listening on 2055')
})