TCP/XML subscription to receive data with NodeJS?

Question

Node.js

Friends. You need to receive information in real time. With inherently synchronous php, a rather frivolous thing turns out. Started learning NodeJS. But ran into a problem. The system itself works as follows: With its first request, the client announces to the server the
version of the TCP / XML protocol used: The server reports that it is ready to work with the specified protocol version: Well, then we also pass the login, password that we need to receive, and the subscribe command and the system upon receipt of the data will from send to us. So in php it is solved like this:
<proto ver="1.0"/>
<proto ver="1.0">OK</proto>

$socket = socket_create(AF_INET, SOCK_RAW, SOL_TCP);
    //AF_INET - семейство протоколов
    //SOCK_STREAM - тип сокета
    //SOL_TCP - протокол
  $result = socket_connect($socket, $address, $port);
  $msg = '<proto ver="1.0"/>';
  echo "Сообщение серверу: $msg\n";
    socket_write($socket, $msg, strlen($msg)); //Отправляем серверу сообщение
  $out = socket_read($socket, 128); //Читаем сообщение от сервера
var_dump($out);

But here the trick is that in PHP you can choose the raw socket type. And the answer comes. And the subscription works. But unfortunately not for long. And it is impossible to control the shutdown process. Here is the JS code which, unfortunately, does not return a response. I so understand that it is knocked on telnet.

var net = require('net');
var HOST = '172.16.221.106';
var PORT = 14074;

var loopConnection = function() {
    var client = new net.Socket();

    client.connect(PORT, HOST, function() {
        console.log('CONNECTED TO: ' + HOST + ':' + PORT);
        client.write('<proto ver="1.0"/>');
    });

    client.on('data', function(data) {
        console.log('DATA: ' + data.toString());
        client.destroy();
    });

    client.on('close', function() {
        console.log('Connection closed');
        setTimeout(function() {
            loopConnection(); // restart again
        }, 1000); // Wait for one second
    });
};

loopConnection(); // Initialize and first call loopConnection

installed raw-socket but it only creates a server. there is no client functionality. How to be, where to dig, what to study?
ps for help I will throw off mogarych on kiwi or a card =)

Answer 1

Something like this should happen?

const net = require('net');
const HOST = '172.16.221.106';
const PORT = 14074;
const client = new net.Socket();

let socketData = '';
let socketWaitHello = true;

client.connect(PORT, HOST);

client.on('connect', () => {
  console.log(`CONNECTED TO: ${HOST}:${PORT}`);
  client.write(`<proto ver="1.0"/>`);
  socketWaitHello = true;
});

client.on('data', (data) => {
  socketData += data.toString();
});

client.on('end', () => {
  console.log(`DATA: ${socketData}`);
  if (socketWaitHello) {
    if (socketData === `<proto ver="1.0">OK</proto>`) {
      client.write(`<some_auth_data />`);
    }
    else if (socketData === `<auth_is_accepted />`) {
      socketWaitHello = false;
      client.write(`<get_some_data />`);
    }
    else {
      throw new Error(`Server don't answered for hello`);
    }
  }
  else {
    do_something_with_data(socketData);
  }

  socketData = '';
});

client.on('close', () => {
  console.log(`Connection closed`);
});