Python server programming: the simplest socket server implementation

With the rapid development of cloud computing and Internet of Things technology, network programming has become an increasingly important skill. Python is a popular programming language and one of the commonly used languages ​​for network programming. Socket is one of the most important network programming modules in Python and can implement various network applications. This article will introduce the basic concepts and simple usage of the Socket module in Python, and provide the simplest Socket server implementation.

1. Basic concepts of Socket module

Socket is a communication technology that allows different applications to communicate on the network. In Python, Socket is a built-in network programming module that is used to implement various network applications, such as Web servers, FTP servers, SMTP servers, and various client applications. In Socket programming, both ends of the communication require a Socket object.

There are four types of Socket: stream socket (TCP), datagram socket (UDP), raw socket (RAW) and signal socket (SIGNAL). Among them, TCP is a streaming Socket, which can achieve reliable and continuous data transmission when communicating on the network through TCP; UDP is a datagram Socket, which can transmit data when the network is unreliable; RAW is a raw set Socket, which can operate lower-level protocols; SIGNAL is a signal socket, which can realize communication between processes.

2. Basic usage of the Socket module in Python

To use the Socket module in Python, you need to import the module first:

import socket

Create a Socket object:

sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

Among them, socket.AF_INET means using the IPv4 protocol, and socket.SOCK_STREAM means using the TCP transmission protocol. If you need to use UDP transmission protocol, you need to declare it like this:

sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)

Then, you can bind the IP address and port through the bind() method:

sock.bind(('127.0.0.1', 8080))

Where, '127.0.0.1' means The IP address of this machine, 8080 represents the port number.

Finally, you can listen to the client's connection request through the listen() method, and receive the client's connection through the accept() method:

sock.listen(5)
while True:
    conn, addr = sock.accept()
    data = conn.recv(1024)
    print(data.decode())
    conn.sendall('Hello, client'.encode())
    conn.close()

Among them, listen(5) means the most in the queue 5 connection requests are allowed, more than 5 will be rejected. The accept() method returns a connected Socket object (conn) and client address (addr). When receiving data sent by the client, you can use the recv() method, and when sending data, you can use the sendall() method. Finally, remember to close the connection.

3. The simplest Socket server implementation

Finally, let’s look at the simplest Socket server implementation, which is used to receive the client’s connection request and return " Hello, client":

import socket

sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.bind(('127.0.0.1', 8080))
sock.listen(5)

while True:
    conn, addr = sock.accept()
    data = conn.recv(1024)
    print(data.decode())
    conn.sendall('Hello, client'.encode())
    conn.close()

Run this script in the terminal. You can see that the server has started listening for connection requests on port 8080. At this time, you can use the telnet tool to simulate a client and connect to the server:

telnet 127.0.0.1 8080

After the connection is successful, you can enter any string on the client, and the server will return "Hello, client". At this point, the simplest Socket server implementation is completed.

Summary

By reading this article, you have already understood the basic concepts and simple usage of the Socket module in Python, and how to implement the simplest Socket server. Socket is one of the most important network programming modules in Python, which can implement various network applications, such as Web servers, FTP servers, SMTP servers, and various client applications. If you need to do network programming, Socket is one of your indispensable tools.

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