Python socket network programming TCP and IP servers communicate with clients

Python socket network programming

Beginners python, recently bought two books "python programming from entry to practice" the 3rd edition Python core programming, first book is primarily concerned with the use of some basic grammar and 1 some basic method, while the second is much deeper, his opinion is 1 and half know solution, just see this part of the network programming, there are still many don't understand of place, but want to come through oneself constantly, constantly looking for learning, should become fully in the morning and evening...

The main module used in this part is the socket module. In this module, you can find the socket() function, which is used to create socket objects. Sockets also have their own set of methods, which can realize network communication based on sockets.

socket() module function

To create a socket, you must use the socket.socket () function, which has the following 1-like syntax

socket(socket_family, socket_type, protocol=0)

Where socket_family is AF_UNIX or AF_INET,socket_type is SOCK_STREAM or SOCK_DGRAM, protocol is usually omitted, default =0.

So to create an TCP/IP socket, you can call socket.socket () in the following manner.

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

Also create the UDP/IP socket using the method call below

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

Create the TCP server

The process for creating an TCP server is as follows, not the actual code

ss = socket()          # Create a server socket 
    ss.bind()              # A socket is bound to an address 
    ss.listen()             # Listening to the connection 
    inf_loop:             # Server infinite loop 
        cs = ss.accepr()   # Accept client connections 
        comm_loop:      # Communication cycle 
            cs.recv()/cs.send()   # Dialogue (receive / Send) 
        cs.close()        # Close the client socket 
    ss.close()            # Close the server socket (optional) 

In practice, the basic process of creating TCP server is as mentioned above, which may be slightly different, but the basic idea should be the same. Here is the code of the real server:

#!/usr/bin/env python
# -*- coding: utf-8 -*-

from socket import *      # will  socket  Attributes are introduced into the namespace 

HOST = ''          # This is the  bind() The identifier of the method indicates that any available address can be used 
PORT = 21571      # The port number 
BUFSIZ = 1024     # Buffer size, 1kb
ADDR = (HOST,PORT)   # Address?? 

tcpSerSocket = socket(AF_INET,SOCK_STREAM)    # create  tcp  The socket 
tcpSerSocket.bind(ADDR)           # Binds the address to the socket 
tcpSerSocket.listen(5)            # Sets and starts socket listening 

while True:        # Loop indefinitely, waiting for the client to connect 
  print('waiting for connection...')   
  tcpCliSocket,addr = tcpSerSocket.accept()    # Passively accept client connections      
  print('...connected from:',addr)

  while True:      # The dialog loops, waiting for the client to send the message 
    data = tcpCliSocket.recv(BUFSIZ)   # Receive client messages 
    if not data:     # If the message is blank, jump out of the dialog loop and close the current connection 
      break
    tcpCliSocket.send(data)   # If a message is received, it is returned to the client intact 

  tcpCliSocket.close()
tcpSerSocket.close()

Create the TCP client

As in 1 above, a simple non-code flow

cs = socket()    # Create a client socket 
    cs.connect()     # Trying to connect to the server 
    comm_loop:     # Communication cycle 
        cs.send()/cs.recv()  # Conversation (send / Receive) 
    cs.close()       # Close the client socket 

Actually creating a client is also a step above translation

#!/usr/bin/env python
# -*- coding: utf-8 -*-

from socket import *

HOST = 'localhost'    # The hostname of the server 
PORT = 21571     # The port number 
BUFSIZ = 1024     # The buffer 
ADDR = (HOST,PORT)   # address 

tcpCliSocket = socket(AF_INET,SOCK_STREAM)  # Create a client socket 
tcpCliSocket.connect(ADDR)     # Connect to server 

while True:        # Communication cycle 
  data = input('> ')    # The client enters the information 
  if not data:   # If the input information is empty, the loop is broken and the communication is turned off 
    break

  data = str.encode(data)      
  tcpCliSocket.send(data)   # Send client information 
  data = tcpCliSocket.recv(BUFSIZ)   # Accept the information returned by the server 
  if not data:    # If the server does not return information, close the communication loop 
    break
  print('get:',data.decode('utf-8'))

tcpCliSocket.close()

Of course, this is only the most basic communication, and about the host name, port number and other things for the time being not very well understood, at present what is done is only on the same computer communication, port number also need 1, if different computers to communicate what to do? I'm just a little white...

Thank you for reading, I hope to help you, thank you for your support of this site!