TCP network application development process

Catalog

One 、TCP Introduction of network application development process

1、TCP Introduction of client program development process

2、TCP Introduction of server program development process

Two 、TCP Client development

3、 ... and 、TCP Server program development

Four 、TCP Attention to web applications

5、 ... and 、socket And send and recv principle

1、 know TCP socket Send and receive buffers

2、send Principle analysis

3、recv Principle analysis

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One 、TCP Introduction of network application development process

TCP Network application development is divided into ：

TCP Client development

TCP Server program development

explain ： Client program refers to the program running on user equipment 　 The server program is a program running on the server device , Dedicated to providing data services for clients

1、TCP Introduction of client program development process

Step-by-step instructions ：

        １. Create client socket object

        ２. Establish a connection with the server socket

        ３. The data

        ４. receive data

        ５. Close client socket

2、TCP Introduction of server program development process

Step-by-step instructions ：　

        １. Create a server socket object 　

        ２. Binding port number 　

        ３. Set listening

        ４. Waiting to accept the connection request from the client

        ５. receive data

        ６. send data

        ７. Close socket

Two 、TCP Client development

Step-by-step instructions ：

        １. Create client socket object

        ２. Establish a connection with the server socket

        ３. The data

        ４. receive data

        ５. Close client socket

Developing code ：

import socket
if __name__ == '__main__':

    #  establish tcp Client socket 
    # AF_INET：ipv4 Address type 
    # SOCK_STREAM：tcp Transport protocol type 
    tcp_client_socket = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
    #  Establish a connection with the server socket 
    tcp_client_socket.connect(("192.168.68.160",8080))

    send_content = "hello"
    #  Encode the string process into binary data 
    send_data = send_content.encode("gbk")
    #  Send data to the server 
    tcp_client_socket.send(send_data)
    #  Receive server data 
    recv_data = tcp_client_socket.recv(1024)
   
    #  Decode the binary 
    recv_content = recv_data.decode("gbk")
    print(recv_content)
    #  Close socket 
    tcp_client_socket.close()

Connect the network debugging assistant to the client instead of the server , The test results are as follows ：

The client connects to the server , After successful connection , The client sends... To the server “hello” Information .

 

After the server sends information to the client , After the client successfully receives the information , Close the connection with the server , The information sent by the server is displayed in the console of the client .

 

 

 

 

 

3、 ... and 、TCP Server program development

import socket

if __name__ == '__main__':
    #  establish tcp The socket of the server 
    tcp_server_socket = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
    #  Port number multiplexing 
    tcp_server_socket.setsockopt(socket.SOL_SOCKET,socket.SO_REUSEADDR,True)
    #  Binding port 
    tcp_server_socket.bind(("",8080))
    #  Set listening 
    tcp_server_socket.listen(128)
    #  Waiting to accept the connection request from the client 
    #  Be careful ： When the connection between the client and the server is successful, a new socket will be returned 
    # tcp_serve It is only responsible for waiting to receive the connection request from the client , This socket is not used for sending and receiving messages 
    new_client,ip_port = tcp_server_socket.accept()
    print(" Client's IP And port number ：",ip_port)
    #  Receiving data from clients 
    recv_data = new_client.recv(1024)
    #  Decoding binary data 
    recv_content = recv_data.decode("gbk")
    print(" Receiving data from clients ：",recv_content)
    #  Send data to client 
    send_content = " The problem is being dealt with "
    send_data = send_content.encode("gbk")
    new_client.send(send_data)
    new_client.close()
    #  Close the server socket , It means that the socket of the server will no longer wait for the connection request of the client 
    tcp_server_socket.close()

When the server program runs , Use the network debugging assistant as the client , Connect with the server , When the connection is successful , The console of the server will print , Currently connected to the client IP And port number .

 

 

When sending messages to the server on the client , After the server receives the message , Will send a message to the client , Finally, close the server .

 

 

Four 、TCP Attention to web applications

1. When TCP The client program wants to start from TCP When the server program communicates, it must first establish a connection

2. TCP Client programs generally do not need to bind port numbers , Otherwise, the client will actively initiate the establishment of a connection

3. TCP The server program must bind the port number , Otherwise, the client cannot find this TCP Server program

4. listen The socket after is a passive socket , Only responsible for receiving connection requests from new clients , Can't send or receive messages

5. When TCP Client programs and TCP After the server program is successfully connected ,TCP The server will generate a new socket , Receive client messages using this socket

6. close accept The socket returned means that the communication with the client has been completed

7. close listen The latter socket means that the socket of the server is closed , It will cause the new client to fail Connect server , But the clients that have been successfully connected before can still communicate normally

8. When the client's socket calls close after , Server side recv Unblock , The length of the data returned is 0, The server can judge whether the client is offline by the length of the returned data , On the contrary, the server closes the socket , Client's recv It will also unblock , The length of the data returned is 0

5、 ... and 、socket And send and recv principle

1、 know TCP socket Send and receive buffers

When creating a TCP socket Object will have a send buffer and a receive buffer , This send and receive buffer refers to a piece of space in memory

2、send Principle analysis

send You have to send data through your network card , Applications can't send data directly through the network card , It needs to call the operating system interface , in other words , The application sends data to the send buffer first （ A piece of memory ）, Then the operating system controls the network card to send the data of the sending buffer to the server network card

3、recv Principle analysis

Application software cannot accept data through network card , It needs to have an operating system interface , The operating system receives data through the network card , Write the received data to the receive buffer （ A piece of memory ）, The application program then obtains the data sent by the client from the receiving buffer