How to use the socket module to create clients and servers in Python 2.x

Python is a widely used programming language that is concise and easy to read. Among them, the socket module is an important module for network programming in Python. It can easily create clients and servers and implement network communication. This article will introduce in detail how to use the socket module to create clients and servers in Python 2.x, and come with code examples.

1. Overview of the socket module
The socket module is one of Python's standard libraries. It provides network-related functions and classes that can be used to create various types of sockets (sockets). Through sockets, communication between different computers can be achieved, including requests and responses, file transfers, etc.

In Python 2.x, the socket module mainly provides two types of sockets: stream sockets (socket.SOCK_STREAM) and datagram sockets (socket.SOCK_DGRAM). Stream sockets can be used to establish reliable, connection-based communication, while datagram sockets are used for connectionless communication.

2. Create a client

1. Import the socket module
   First, you need to import the Python socket module in order to use the functions and classes in it.

import socket

2. Create socket
   Before creating a client, you need to use the socket.socket() function to create a socket. This function accepts two parameters. The first parameter is the Address Family, which specifies the type of socket (such as IPv4 or IPv6). The second parameter is the socket type (stream socket or datagram socket). interface).

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

3. Connecting to the server
   A connection can be established with the server by using the connect() method of the client socket. This method accepts one parameter, the server's IP address and port number, in the form of a tuple. After a successful connection, a new socket will be returned for communication.

server_address = ('192.168.0.100', 8080)
client_socket.connect(server_address)

4. Send and receive data
   Send data to the server by using the send() method of the client socket, and receive data returned by the server using the recv() method. The send() method accepts a string parameter, while the recv() method accepts an integer parameter to specify the maximum length of data to be received.

data = 'Hello, server!'
client_socket.send(data)
response = client_socket.recv(1024)
print response

5. Close the socket
   After the client and server communication is completed, the socket should be closed to release resources. A socket can be closed by using the client socket's close() method.

client_socket.close()

3. Create a server

1. Import the socket module
   Same as creating a client, you first need to import the socket module.

import socket

2. Create socket
   Use the socket.socket() function to create a socket, specify the address family and socket type. At the same time, the socket needs to be set up to be reusable so that it can be restarted immediately after the server shuts down unexpectedly.

server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)

3. Bind server address
   By using the bind() method of the server socket, the server address can be bound to the socket. This method accepts one parameter, a tuple containing the IP address of the server host and the port number it is listening on.

server_address = ('', 8080)
server_socket.bind(server_address)

4. Listening for connection requests
   The server socket needs to use the listen() method to start listening for connection requests. This method accepts a parameter that specifies the maximum number of connections that the server can handle at the same time.

server_socket.listen(5)

5. Accept connections and process requests
   You can accept connections from clients by using the accept() method of the server socket. This method will return a new socket for communication with the client. During the communication with the client, you can use the recv() method to receive the data sent by the client, and the send() method to send the response data.

client_socket, client_address = server_socket.accept()
data = client_socket.recv(1024)
print data
response = 'Hello, client!'
client_socket.send(response)

6. Close the socket
   After the server has completed all processing, the socket should be closed. A socket can be closed by using the server socket's close() method.

server_socket.close()

With the above steps, you can easily create clients and servers using the socket module in Python 2.x. The code can be appropriately modified and optimized according to actual needs to achieve more complex and efficient network communication.

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