Net Module in Node

In Node.js, The Net module provides a set of asynchronous network functions for creating servers and clients.

It is part of the core modules and is commonly used for building networking applications such as TCP servers and clients.

Overview of some key functionalities provided by the net module:

Creating a TCP Server:

The "net.createServer" method is used to create a "TCP" server. It takes a callback function that will be called when a client connects.

Example:

const net = require('net');

const server = net.createServer((socket) => {
  console.log('Client connected');

  // Handle data from the client
  socket.on('data', (data) => {
    console.log(`Received data: ${data}`);
  });

  // Handle the end of the connection
  socket.on('end', () => {
    console.log('Client disconnected');
  });
});

// Listen on a 8000 port on localhost
const PORT = 8000;

server.listen(PORT, () => {
  console.log(`Server listening on http://localhost:${PORT}`);
});

Output:

Server listening on 127.0.0.1:8000
Client connected
Received data: Hello, server!

Creating a TCP Client:

The "net.createConnection" method is used to create a TCP Client that can connect to a TCP Server.

Example:

const net = require('net');

const client = net.createConnection({ port: 8000, host: 'localhost' }, () => {
  console.log('Connected to client');

  // Send data to the server
  client.write('Hello, server!');
});

// Handle data received from the server
client.on('data', (data) => {
  console.log(`Received data from server: ${data}`);
});

// Handle the end of the connection
client.on('end', () => {
  console.log('Disconnected from server');
});

Output:

Connected to client

Handling Errors:

Both the server and client can emit error events, and it's important to handle these events to prevent crashes.

Error Handling:

Example:

server.on('error', (err) => {
  console.error(`Server error: ${err}`);
});

client.on('error', (err) => {
  console.error(`Client error: ${err}`);
});

Closing the Server:

To stop the server, we can call its `close` method. This will close the server and stop it from accepting new connections.

Example:

server.close(() => {
  console.log('Server closed');
});

Event: 'connection':

The 'connection' event is emitted when a new connection is established. The callback function receives a socket object representing the connection.

Example:

server.on('connection', (socket) => {
  console.log('New connection established');
});

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