Socket is an abstract layer of TCP/IP network communication, which provides a series of data interaction operation interfaces, so that developers can no longer pay attention to the details of specific protocol processing, so that their programs can quickly realize network data interaction.
To put it simply, program processes need to communicate through sockets, which is similar to a plug-in, and all processes must be associated to work. As long as it is an application related to the network, sockets must be used.
Socket programming in Python is generally divided into two communication protocols, TCP and UDP, and socket is based on C/S architecture, so socket network programming requires writing client programs and server programs.
TCP communication process
client process
Initializesocket()
Use ip and port number connect() to connect to the server
Use recv() to receive data, send() to send data to interact with the server
closesocket()
Server process
Initializesocket()
Use bind() to bind ip and port number
Use listen() to listen for messages
Get the client's socket address accept()
Use recv() to receive data, send() to send data to interact with the client
closesocket()
Use the socket.socket class in Python to realize TCP program developmentsocket.socket(AddressFamily, Type)
Parameter Description:
AddressFamily indicates the type of IP address, divided into TPv4 and IPv6
Type indicates the transport protocol type
Common methods are as follows:
| function | describe |
|---|---|
| socket() | Get the socket class object |
| bind((hostname, port)) | Bind and listen on the port of the specified host |
| listen() | Enable monitoring on the bound port, the parameter indicates the maximum number of connections waiting to be established |
| accept() | Wait for the client to connect, and return the client address after connection |
| send(data) | Send data, data is binary data |
| recv(buffer) | Indicates received data, buffersize is the length of each received data |
| close() | close socket connection |
| connect((hostname, port)) | Set the host name and port number to connect to |
Use Python to implement TCP communication code:
Service-Terminal:
import socket
# 创建一个socket对象，默认TCP套接字
s = socket.socket()
# 绑定端口
s.bind(('127.0.0.1',9006))
# 监听端口
s.listen(5)
print("正在连接中……")
# 建立连接之后，持续等待连接
while 1:
# 阻塞等待连接
sock,addr = s.accept()
print(sock,addr)
# 一直保持发送和接收数据的状态
while 1:
text = sock.recv(1024)
# 客户端发送的数据为空的无效数据
if len(text.strip()) == 0:
print("服务端接收到客户端的数据为空")
else:
print("收到客户端发送的数据为：{}".format(text.decode()))
content = input("请输入发送给客户端的信息：")
# 返回服务端发送的信息
sock.send(content.encode())
sock.close()
client:
import socket
# 创建一个socket对象
s1 = socket.socket()
s1.connect(('127.0.0.1', 9006))
# 不断发送和接收数据
while 1:
send_data = input("客户端要发送的信息：")
# socket传递的都是bytes类型的数据,需要转换一下
s1.send(send_data.encode())
# 接收数据，最大字节数1024,对返回的二进制数据进行解码
text = s1.recv(1024).decode()
print("服务端发送的数据：{}".format(text))
print("------------------------------")
Because network communication needs to find the device in the network through the ip address, and find the port of the corresponding process through the port number, the client ip port must be consistent with the client ip port.
When the connection between the client and the server is established, the port number will not be released immediately after exiting the program, and it needs to wait for about 1-2 minutes. It can be solved by setting port multiplexing (
tcp_server_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, True))
The above code realizes that the TCP server program can only serve one client. If the server program wants to communicate with multiple clients, multi-threading or modules can be used. Socketserver is a repackage socketserverof socket, thus simplifying socket network programming. method.
For more information about the use of python socket, you can check the official documentation to learn:
https://docs.python.org/zh-cn/3/library/socketserver.html#module-socketserver
https://docs.python.org/zh-cn/3/library/socket.html
https://docs.python.org/zh-cn/3/howto/sockets.html
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