Python server programming: from protocol understanding to practice

As an efficient and easy-to-learn programming language, Python has a rich and easy-to-use network programming library, so it has become one of the preferred languages ​​for server-side development. Python server programming is a skill that requires an in-depth understanding of protocol and network fundamentals, as well as proficiency in using the Python programming language and related libraries. This article will introduce the basic knowledge and skills of Python server programming from protocol understanding to coding practice.

In-depth understanding of protocols

The network is a complex system. Its basic unit is a data packet, and its transmission depends on various protocols. In Python server programming, you need to have an in-depth understanding of network protocols, which is the basis of server programming. The following are commonly used network protocols:

1. TCP/IP protocol: It is one of the most important network protocols in history and is responsible for the segmentation, transmission and routing of data. The TCP/IP protocol is used for all transmissions on the Internet, including email, FTP, HTTP protocols, etc.
2. HTTP protocol: It is one of the most widely used protocols above the TCP/IP protocol and is used for document transmission on the World Wide Web. The HTTP protocol is based on the request-response model. The client sends a request to the server and the server replies with corresponding data.
3. Websocket protocol: It is a long connection protocol based on the HTTP protocol, which can realize real-time data transmission and active push by the server. The websocket protocol is widely used in online games, real-time communication and other fields.
4. FTP protocol: It is a file transfer protocol on top of the TCP/IP protocol, used to transfer files from one host to another. The FTP protocol supports multiple modes of transmission, including ASCII mode and binary mode.

Python server programming skills

Python server programming requires the use of many library functions and techniques, the most important of which is the socket library. Next, we will start with the use of the socket library and explain the skills and key points of Python server programming.

1. Create socket object

Python's socket library encapsulates the underlying socket API and is used to implement network applications. In Python, use the socket.socket() function to create a socket object, whose parameters include socket_family, socket_type and protocol. The following are the basic steps to create a socket object:

import socket

# 创建TCP socket
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

# 创建UDP socket
sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)

2. Bind port and IP address

The server needs to bind a port and an IP address to listen to the client Connection request. Use the socket.bind() function to bind a socket object to a specified port and IP address.

import socket

# 创建TCP socket对象
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

# 绑定到指定的IP和端口
sock.bind(('127.0.0.1', 9000))

# 监听客户端连接
sock.listen(5)

3. Accept client connections

While the server is running, clients will make connection requests, and the server needs to be able to accept these requests. Using the socket.accept() function, the server can accept the client's connection request.

import socket

# 创建TCP socket对象
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

# 绑定到指定的IP和端口
sock.bind(('127.0.0.1', 9000))

# 监听客户端连接
sock.listen(5)

while True:
    # 等待客户端连接
    client, addr = sock.accept()
    print(f'客户端 {addr} 已连接')

    # 处理客户端请求
    while True:
        data = client.recv(1024)
        if not data:
            break
        client.sendall(data)

    # 关闭客户端连接
    client.close()

4. Processing request data

After the client establishes a connection with the server, the client needs to send request data to the server. In Python server programming, you can use the socket.recv() function to receive client data. After receiving the data, the server can process the data and return a response to the client.

import socket

# 创建TCP socket对象
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

# 绑定到指定的IP和端口
sock.bind(('127.0.0.1', 9000))

# 监听客户端连接
sock.listen(5)

while True:
    # 等待客户端连接
    client, addr = sock.accept()
    print(f'客户端 {addr} 已连接')

    # 处理客户端请求
    while True:
        data = client.recv(1024)
        if not data:
            break
        print(f'从客户端收到数据：{data.decode()}')
        client.sendall(data)

    # 关闭客户端连接
    client.close()

5. Send response data

After the client receives the response data, it will process it accordingly based on the response content. Similarly, in Python server programming, you can use the socket.sendall() function to send response data to the client.

import socket

# 创建TCP socket对象
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

# 绑定到指定的IP和端口
sock.bind(('127.0.0.1', 9000))

# 监听客户端连接
sock.listen(5)

while True:
    # 等待客户端连接
    client, addr = sock.accept()
    print(f'客户端 {addr} 已连接')

    # 处理客户端请求
    while True:
        data = client.recv(1024)
        if not data:
            break
        print(f'从客户端收到数据：{data.decode()}')
        client.sendall(f'收到数据：{data.decode()}'.encode())

    # 关闭客户端连接
    client.close()

Summary

Python server programming is an advanced skill that requires an in-depth understanding of network protocols and Python programming skills. In this article, we discuss the basic knowledge and skills of Python server programming, from understanding the protocol to the practice of code, so that readers can understand how to use Python to write server programs. It is recommended that readers further learn Python server programming, master more skills, and apply them to actual projects.

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