Socket Communications underlying principle

Socket communication principles underlying 
the application memory to copy the operating system, the operating system to follow the TCP protocol to send the other party, the other party receives the transmission signal and

from socket import *

client = socket(AF_INET, SOCK_STREAM)
client.connect(('127.0.0.1', 8081))

# 通信循环
while True:
    msg=input('>>: ').strip() #msg=''
    if len(msg) == 0:continue
    client.send(msg.encode('utf-8')) #client.send(b'')
    print('has send')
    data=client.recv(1024)
    print('has recv')
    print(data)

client.close()

Client

# Server must meet at least three things: 
# 1 binds a fixed ip and Port 
# 2. external services has been stable operation 
# 3 is capable of supporting concurrent 
from socket Import * 

Server = socket (AF_INET, SOCK_STREAM) 
Server. the bind (( ' 127.0.0.1 ' , 8081 )) 
server.listen ( . 5 ) 

# links circulating 
the while True: 
    Conn, client_addr = server.accept ()
     Print (client_addr) 

    # communications cycle 
    the while True:
         the try : 
            Data = conn.recv (1024)
             IF len (Data) == 0: BREAK   # for linux system 
            Print ( ' -> receiving the client message: ' , Data) 
            conn.send (data.upper ()) 
        the except ConnectionResetError:
             BREAK 

    conn.Close () 

server.close ()

Server