I'm integrating websockets with express on the backend and using browser's native websocket api on the client side. I have so far been able to send and receive message from the client to server and server back to client. But all this happens with a page refresh only. Isn't websocket supposed to be real time? Lets say I make a change in the message on server file, then it has to immediately reflect in my browser's console. and lets say I make a change in the message in the script file on the client side, then it has to immediately show the changes on server's console.(Also I'm using nodemon to run the server so changes has to reflect pretty quickly). But right now, I see myself making a request to / via page refresh and then server upgrading and then responding back with the message.
Please tell me if I'm missing something in the code or otherwise in the concept?
app.js
const express = require('express')
const app = express()
const path = require('path')
const WebSocketServer = require('websocket').server;
app.set('view engine', 'html');
app.use(express.static(path.join(__dirname, '/public')))
const port = 8080
app.get('/', (req, res) => {
res.render('index')
})
const server = app.listen(port, () => {
console.log(`Example app listening on port ${port}`)
})
wsServer = new WebSocketServer({
httpServer: server
});
function originIsAllowed(origin) {
return true;
}
wsServer.on('request', function(request) {
if (!originIsAllowed(request.origin)) {
request.reject();
console.log((new Date()) + ' Connection from origin ' + request.origin + ' rejected.');
return;
}
var connection = request.accept(null, request.origin);
console.log((new Date()) + ' Connection accepted.');
connection.on('message', function(message) {
if (message.type === 'utf8') {
console.log('Received Message: ' + message.utf8Data);
connection.sendUTF("server says hi");
}
else if (message.type === 'binary') {
console.log('Received Binary Message of ' + message.binaryData.length + ' bytes');
connection.sendBytes(message.binaryData);
}
});
connection.on('close', function(reasonCode, description) {
console.log((new Date()) + ' Peer ' + connection.remoteAddress + ' disconnected.');
});
});
client.js:
const socket = new WebSocket('ws://localhost:8080');
// Connection opened
socket.addEventListener('open', function (event) {
socket.send('Hello to Server!');
});
// Listen for messages
socket.addEventListener('message', function (event) {
console.log('Message from server ', event.data);
});
I am not sure if I understand the question, but if you want the client to send message to server, you have do it the same way as it is done in open listener:
socket.send('MESSAGE FOR SERVER') or, if server should send something to client, then just
connection.send('MESSAGE FOR CLIENT').
Realtime communication with WebSocket means, the connection is created only once and the protocol is kept opened (Unlike REST API, where the connection is created with every request.)
The message must be sent actively either from server or client, there is nothing observing some message state and updating it on the other side.
Related
I am trying to build/deploy a tracker server for use with P2P applications using the below code. It works fine locally, but when I deploy it to Heroku, the port bindings fail because only one port is allowed.
// Create a web sockets signaling server
var express = require('express');
var bodyParser = require('body-parser');
var app = express();
//Allow all requests from all domains & localhost
app.all('/*', function(req, res, next) {
res.header("Access-Control-Allow-Origin", "*");
res.header("Access-Control-Allow-Headers", "X-Requested-With, Content-Type, Accept");
res.header("Access-Control-Allow-Methods", "POST, GET");
next();
});
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({extended: false}));
let lookup = {}
const hostname = '0.0.0.0';
const port = process.env.PORT;
var Server = require('bittorrent-tracker').Server
var server = new Server({
udp: false, // enable udp server? [default=true]
http: true, // enable http server? [default=true]
ws: true, // enable websocket server? [default=true]
stats: true, // enable web-based statistics? [default=true]
})
server.on('error', function (err) {
// fatal server error!
console.log(err.message)
})
server.on('warning', function (err) {
// client sent bad data. probably not a problem, just a buggy client.
console.log(err.message)
})
server.on('listening', function () {
// fired when all requested servers are listening
console.log('Signal server http port:' + server.http.address().port)
console.log('Signal server ws port:' + server.ws.address().port)
})
// start tracker server listening! Use 0 to listen on a random free port.
server.listen(port, hostname, 'listening')
// listen for individual tracker messages from peers:
server.on('start', function (addr) {
console.log('got start message from ' + addr)
Object.keys(server.torrents).forEach(hash => {
lookup[server.torrents[hash].infoHash] = server.torrents[hash].peers.length
console.log("peers: " + server.torrents[hash].peers.length)
})
})
server.on('complete', function (addr) {})
server.on('stop', function (addr) {})
app.get('/peers', function(req, res) {
res.send(lookup);
})
app.listen(process.env.PORT, function() {
console.log('Express server port: ' + this.address().port); //Listening on port #
})
If I use process.env.PORT for both server and app, I get the following, which is expected since Heroku only allows 1 listen port:
2021-02-13T05:35:31.016101+00:00 heroku[web.1]: State changed from starting to up
2021-02-13T05:35:30.885170+00:00 app[web.1]: Express server port: 9898
2021-02-13T05:35:30.885204+00:00 app[web.1]: listen EADDRINUSE: address already in use 0.0.0.0:9898
2021-02-13T05:35:30.885205+00:00 app[web.1]: listen EADDRINUSE: address already in use 0.0.0.0:9898
If I hard code the port for either server or app, the application launches fine, but the signaling server doesn't work. No substantial logging is generated.
2021-02-13T05:38:21.141806+00:00 heroku[web.1]: State changed from starting to up
2021-02-13T05:38:20.998054+00:00 app[web.1]: Express server port: 25702
2021-02-13T05:38:20.998550+00:00 app[web.1]: Signal server http port:31415
2021-02-13T05:38:20.998683+00:00 app[web.1]: Signal server ws port:31415
Is it possible that the bittorrent-tracker server and express server can use the same port? For instance, could I get and return the list of peers within this block of code without the need for express at all?
server.on('start', function (addr) {
console.log('got start message from ' + addr)
// Could I do something here to eliminate the need for Express?
Object.keys(server.torrents).forEach(hash => {
lookup[server.torrents[hash].infoHash] = server.torrents[hash].peers.length
console.log("peers: " + server.torrents[hash].peers.length)
})
})
The documentation states:
The http server will handle requests for the following paths:
/announce, /scrape. Requests for other paths will not be handled.
But perhaps there is some way I can shim in the requests that express is handling?
Not long after asking this question, it occurred to me that I might not need express at all. It turns out that was correct.
For anyone wanting a Heroku-ready bittorrent-tracker, here is the updated code:
// Create a web sockets signaling server
let lookup = {}
const hostname = '0.0.0.0';
const port = process.env.PORT;
var Server = require('bittorrent-tracker').Server
var server = new Server({
udp: false, // enable udp server? [default=true]
http: true, // enable http server? [default=true]
ws: true, // enable websocket server? [default=true]
stats: true, // enable web-based statistics? [default=true]
})
server.on('error', function (err) {
// fatal server error!
console.log(err.message)
})
server.on('warning', function (err) {
// client sent bad data. probably not a problem, just a buggy client.
console.log(err.message)
})
server.on('listening', function () {
// fired when all requested servers are listening
console.log('Signal server http port:' + server.http.address().port)
console.log('Signal server ws port:' + server.ws.address().port)
})
// start tracker server listening! Use 0 to listen on a random free port.
server.listen(port, hostname, 'listening')
// listen for individual tracker messages from peers:
server.on('start', function (addr) {
console.log('got start message from ' + addr)
Object.keys(server.torrents).forEach(hash => {
lookup[server.torrents[hash].infoHash] = server.torrents[hash].peers.length
console.log("peers: " + server.torrents[hash].peers.length)
})
})
server.on('complete', function (addr) {})
server.on('stop', function (addr) {})
I am using websocket and http server together, assigning each of them a different port, when a post request hits it sends a message to client using websocket and response of http request is send when client responds to the message.
My problem is I want to create multiple websockets but a single https server, I have tried some things but unable to do it.
Current code for creating websocket and httpserver is
const app = require('express')()
bodyParser = require('body-parser')
app.use(bodyParser.json())
const net = require('net');
var client;
var res1,currentReq;
//----------------------------------------------------------------------------
// http requests listener
//----------------------------------------------------------------------------
app.listen(8001, () => console.log('Http server listening on port 8001'));
//----------------------------------------------------------------------------
// http requests handling
//----------------------------------------------------------------------------
app.post('/getUser', (req, res) => {
console.log(req.body)
res1 = res;
currentReq='getUser';
client.write('{"route":"/","data":{"username":"' + req.body.username +'"}, "res": "' + res + '"}');
//res.end('{"Extension":"' +' data '+ '"}');
console.log("/getUser finished");
// res.end('{"Extension":"' +' data '+ '"}');
});
//----------------------------------------------------------------------------
// Establishing tcp connection for incoming requests
//----------------------------------------------------------------------------
var server = net.createServer(function(connection) {
console.log ('client has connected successfully!');
client = connection;
client.on('data',function(data){
switch(currentReq)
{
case 'getUser' :
console.log('send get user response');
res1.end(data);
break;
}
console.log(data.toString());
//res1.end(data);
});
connection.pipe(connection);
});
//----------------------------------------------------------------------------
// listener for tcp connections
//----------------------------------------------------------------------------
server.listen(8000, function() {
console.log('server for localhost is listening on port 8000');
console.log('server bound address is: ' + server.address ());
});
I have below source code about socket server/client in nodejs.
const net = require('net');
net.createServer((socket)=>{
socket.pipe(socket);
socket.on('data', (data)=>{
console.log('receive data ', data.toString());
socket.write('this is server')
});
}).listen(3000);
console.log("Chat server running at port 5000\n");
let client = new net.Socket();
client.setEncoding('utf8');
client.connect(3000, '127.0.0.1', function() {
console.log('Connected');
client.write('Hello, server! Love, Client.');
});
client.on('data', function(data) {
console.log('Received: ' + data);
});
when I run above code, the server will send the data(which is from the client) back to the client. I know this is cased by socket.pipe(socket);. I want to keep that code and am looking for a way to separate the input/output data in client side like below:
client.on('data', function(data) {
if( the data is sent from client ){
...
} else {
//this is the data generated from server
}
});
Does anyone know how to do that in nodejs client side?
Actually you can separate out the data from client and server, depending upon what messages you emit or what you listen, from that you can distinguish between client and server.
The message you emit from server are the message, you received on the client side if client is listening to that messages, the message you emit by client are the message received on server if server is listening to the messages.
Below is the code for a socket.io
var app = require('express')();
var http = require('http').Server(app);
var io = require('socket.io')(http);
app.get('/', function(req, res){
res.send('<h1>SocketChat Server</h1>');
});
http.listen(3000, function(){
console.log('Listening on *:3000');
});
io.on('connection', function(clientSocket){
/* Here server is listening to client 'connectUser' message so here data is sent from client*/
clientSocket.on('connectUser', function(clientNickname, groupName) {
var message = "User " + clientNickname + " was connected." + clientSocket;
console.log(message);
clientSocket.emit('userConnected');
});
});
/* Here server is emitting message('userConnected') that will be received by client. */
From above you can see that how to distinguish the client and server messages.
I have a use case where I need to take input from browser pass it to my node server over a socket, this input is then send to a third party website for processing again over socket. The result received from the third party website needs to be sent back to browser.
node server
var express = require('express');
var app = express();
var server = require('http').createServer(app);
var socketIO = require('socket.io'),
server, io;
var thirdPartSocketClient = require('socket.io-client');
//Custom imports
var thirdParty = require('./ms_socket.js');
var socket = socketIO(server);
socket.on('connection', function(client) {
var token = null;
//Token from third party site that we should have before sending the actual info
thirdParty.getToken(function callback(returnToken) {
token = returnToken;
});
thirdPartSocketClient = thirdParty.getTranslation(token);
client.on('audio', function(data) {
thirdPartSocketClient.emit(data);
});
});
server.listen(8080, function() {
console.log('Open http://localhost:8080 in your browser');
});
ms_socket.js
//Exported function making a socket call to third party service
var exports = module.exports = {};
var request = require('request');
var wsClient = require('socket.io-client');
var fs = require('fs');
exports.getToken = function(callback) {
//send back the token
}
exports.getTranslation = function(accessToken) {
var ws = new wsClient(thirdPartySocketURL);
// event for connection failure
ws.on('connectFailed', function(error) {
console.log('Initial connection failed: ' + error.toString());
});
// event for connection succeed
ws.on('connect', function(connection) {
console.log('Websocket client connected');
// process message that is returned
//processMessage would process the incoming msg from third party service
connection.on('message', processMessage);
connection.on('close', function(reasonCode, description) {
console.log('Connection closed: ' + reasonCode);
});
// print out the error
connection.on('error', function(error) {
console.log('Connection error: ' + error.toString());
});
});
// connect to the service
ws.connect(thirdPartySocketURL, null, null, {
'Authorization': 'Bearer ' + accessToken
});
return ws;
}; //End of export function
I am able to receive the data from browser, make a connection to third party service (can see the socket connection) and emit the data. however I am unable to receive the reply back from the third part service.
Is it because node is not listening to my socket events of thirdparty ?
Not sure exactly why its not working.
I save the data locally on the server, read the file and then send it, then I get a response back from the service.
If this is not a "right" design can you please suggest a good way, should I be using message queues (if yes, feel free to recommend one)
Thanks
I am using a TCP connection via node.js to connect to a certain port in windows, however I want the connection to be established until the user logs out .
In other words I want to add the TCP Connection as a session attribute in node.js ,so that it will last as long as the session is alive for the user.
I have tried this ,but it doesn't work.
Code :
var express = require('express');
var authRouter = express.Router();
var createTCPConnection = function () {
var net = require('net');
var HOST = '127.0.0.1';
var PORT = 6969;
var client = new net.Socket();
client.connect(PORT, HOST, function() {
console.log('CONNECTED TO: ' + HOST + ':' + PORT);
// Write a message to the socket as soon as the client is connected, the server will receive it as message from the client
client.write('I am Chuck1 Norris!');
});
// Add a 'data' event handler for the client socket
// data is what the server sent to this socket
client.on('data', function(data) {
// Close the client socket completely
//client.destroy();
});
// Add a 'close' event handler for the client socket
client.on('close', function() {
console.log('Connection closed');
});
return client;
};
authRouter.route('/').get(function(req, res) {
var sess = req.session;
if (sess.username) {
//If Session has username attribute, it is a valid session
res.render('dashboard', {
title : 'Welcome To Operator Screen',
username : sess.username
});
if(sess.tcpClient === undefined) {
console.log('Establishing TcpClient');
sess.tcpClient = createTCPConnection();
} else {
console.log('TcpClient already established');
}
} else {
//Invalid/expired session, redirect to homepage
res.redirect('/logout');
}
});
module.exports = authRouter;