Python server programming basics: understanding the TCP/IP protocol

As a high-level programming language, Python has many features and plays an important role in server programming. However, before using Python for server programming, we must understand the TCP/IP protocol. This article will take you through the TCP/IP protocol and its relationship with Python server programming.

TCP/IP protocol:

TCP/IP protocol is a protocol family for application communication in the network. The protocol used in the Internet is the TCP/IP protocol, which includes IP (Internet Protocol) and TCP (Transmission Control Protocol).

IP:

The IP protocol is the standard protocol used for datagram exchange on the Internet. It is mainly responsible for packaging and transmitting data. When we send data over the Internet, the data is broken into many small packets, and each packet is tagged with the source and destination addresses for transmission. When the packets arrive at their destination, the IP protocol is responsible for reassembling them into the original data.

TCP:

TCP protocol is a reliable protocol that runs on top of the IP protocol. It ensures reliability during data transmission by establishing a persistent connection between the client and server to ensure that data is sent and received correctly. The TCP protocol ensures that data is not lost during transmission and is transmitted in the correct order, thereby ensuring data integrity and reliability.

Python server programming basics:

Python server programming usually refers to network programming that communicates with many clients. Python has many libraries for server programming, such as the socket library in the standard library. Using the socket library in Python, we can create a socket object that can listen to a specific port and wait for connection requests from clients.

socket:

Python provides a standard library socket, which is a way to use the TCP/IP protocol for network programming. We can use the socket library to create a socket object that can listen for connection requests from clients and can accept and send data. The following code snippet shows how to create a socket object to listen on port 8888 for connection requests from clients.

import socket

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind(('127.0.0.1', 8888))
s.listen(5)

In the above code, we first create a socket object s and bind it to the IP address 127.0.0.1 and the port number 8888. Use s.listen(5) to indicate that the socket can listen to connection requests from up to 5 clients.

accept method:

After creating the socket object, we can use the accept() method to wait for the connection request from the client. When a connection is established with the client, the accept() method will return a new socket object that can communicate with the client.

while True:
    conn, addr = s.accept()
    # 记录与客户端建立连接的信息
    print("客户端{}已连接".format(addr))
    # 接收客户端发送的数据
    data = conn.recv(1024)
    # 发送数据到客户端
    conn.sendall(b"Hello, client!")
    # 断开与客户端的连接
    conn.close()

In the code snippet, we use an infinite loop to wait for the connection request from the client. When a connection is established with the client, we record the connection information; then use conn.recv() to receive the data sent by the client, and use conn.sendall() to send the data to the client Send a message to the client, and finally use conn.close() to disconnect from the client.

Summary:

This article introduces the basic knowledge of the TCP/IP protocol and how to use sockets for server programming in Python. Understanding the TCP/IP protocol is important for server programming because it describes the underlying structure of Internet data. Creating a server using Python is also relatively simple, we only need to use the socket library.

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