`socket`

The Python socket module provides a low-level networking interface that allows you to create and use sockets for network communication.

It enables Python programs to connect to other computers over a network, send and receive data, and handle network-related tasks like client-server communication.

Here’s a quick example:

>>> import socket

>>> with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
...     s.connect(("www.example.com", 80))
...

Key Features

Creates TCP/IP and UDP sockets
Supports both IPv4 and IPv6 addresses
Provides functions for both synchronous and asynchronous network communication
Offers high-level interfaces for creating server and client applications

Frequently Used Classes and Functions

Object	Type	Description
`socket.socket()`	Class	Represents a network socket
`socket.gethostbyname()`	Function	Resolves a hostname to an IP address
`socket.bind()`	Method	Binds a socket to a local address
`socket.listen()`	Method	Enables a socket to accept incoming connections
`socket.accept()`	Method	Accepts a connection from a client
`socket.recv()`	Method	Receives data from a connected socket
`socket.send()`	Method	Sends data to a connected socket
`socket.close()`	Method	Closes the socket

Examples

Creating a TCP/IP socket:

>>> import socket
>>> s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

Connecting to a server:

>>> s.connect(("www.example.com", 80))

Common Use Cases

Creating client-server applications
Implementing network protocols
Sending and receiving data over TCP/IP and UDP
Building web servers or clients
Developing chat applications

Real-World Example

Here’s how to create a TCP server that listens for incoming connections and sends a welcome message to the client:

import socket
import threading

def handle_client(conn, addr):
    with conn:
        print(f"Connected by {addr}")
        conn.sendall(b"Welcome to the server!")

def main():
    with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
        s.bind(("localhost", 12345))
        s.listen()
        print("Server listening on port 12345...")
        while True:
            conn, addr = s.accept()
            thread = threading.Thread(
                target=handle_client, args=(conn, addr), daemon=True
            )
            thread.start()

if __name__ == "__main__":
    main()

In this example, you use the socket module to create a server that listens on a specified port and sends a welcome message to each client that connects. To try it out, run the script on your computer. You’ll get a message telling you that the server is listening on port 12345. Then, run the following command:

$ nc localhost 12345
Welcome to the server!

socket