Javascript

Socket address type

Client

Node.js uses the type net.Socket. It uses an event driven callback model, so data ead is handled by Socket.on('data', function(data)) {...}. The client is EchoClient.js illustrates this:

//from https://www.hacksparrow.com/nodejs/tcp-socket-programming-in-node-js.html

var net = require('net');

if (process.argv.length < 3) {
    concole.log('Usage: command hostname')
    process.exit(1)
}
hostname = process.argv[2]

var HOST = hostname;
var PORT = 2000;

var client = new net.Socket();
client.connect(PORT, HOST, function() {
  //console.log('CONNECTED TO: ' + HOST + ':' + PORT);
});

// Add a 'data' event handler for the client socket
// data is what the server sent to this socket
client.on('data', function(data) {
    console.log(`Echoed: '${data}'`);
    process.stdout.write("Enter line:")
});

// Add a 'close' event handler for the client socket
client.on('close', function() {
  console.log('Connection closed');
});

// now read from stdin and echo to/from server
const readline = require('readline');

// no newline after prompt
process.stdout.write("Enter line:")

const con = readline.createInterface({
  input: process.stdin,
  output: process.stdout
});

con.on('line', (input) => {
    console.log(`Read line: '${input}'`);
    client.write(input);
    if (input == 'BYE') {
        con.close()
        client.destroy()
	process.exit(0);
    }
});

Multi-threaded server

The server is pretty straightforward, following similar lines to the client: EchoServer.js illustrates this:

//from https://www.hacksparrow.com/nodejs/tcp-socket-programming-in-node-js.html



const net = require('net');
const server = net.createServer((c) => {
    // 'connection' listener.
    console.log('client connected');

    c.on('end', () => {
	console.log('client disconnected');
    });

    c.on('data', function(data) {
	c.write(data);
    });

    c.on('close', function() {
	console.log('Connection closed');
    });

    c.on('error', function() {
	c.destroy();
	console.log('Connection error');
    });
});

server.on('error', (err) => {
    throw err;
});

server.listen(2000, () => {
	console.log('server bound');
    });

Socket options

JavaScript Resources

• TCP socket programming in Node.js

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Copyright © Jan Newmarch, jan@newmarch.name

" Network Programming using Java, Go, Python, Rust, JavaScript and Julia" by Jan Newmarch is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License .
Based on a work at https://jan.newmarch.name/NetworkProgramming/ .

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