This guide walks you through building a simple Python socket server that can handle multiple clients at once, along with a basic client script. Follow these 10 steps to understand the essentials of network programming in Python.

1. Import Required Modules

   import socket
   import threading
   

2. Define a Function to Handle Each Client

   def handle_client(conn, addr):
       print(f"Connected by {addr}")
       data = conn.recv(1024)
       if data:
           print(f"Received from {addr}: {data.decode()}")
           conn.sendall(b"Hello from server!")
       conn.close()
   

3. Set Server Address and Port

   HOST = '127.0.0.1'
   PORT = 5555
   

4. Create a Socket

   with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
   

5. Bind the Socket

       s.bind((HOST, PORT))
   

6. Start Listening for Connections

       s.listen()
       print("Server listening...")
   

7. Accept Clients in a Loop

       while True:
           conn, addr = s.accept()
   

8. Start a New Thread for Each Client

           thread = threading.Thread(target=handle_client, args=(conn, addr))
           thread.start()
   

9. Write the Client Code

   import socket
   
   HOST = '127.0.0.1'
   PORT = 5555
   
   with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
       s.connect((HOST, PORT))
       s.sendall(b"Hello from client!")
       data = s.recv(1024)
       print(f"Received from server: {data.decode()}")
   

10. Run and Test
    • Start the server: python server.py
    • Run client.py in one or more terminals.
    • Each client will connect, send a message, and receive a response.
    • The server will handle all clients simultaneously!