python-study-29

Review

Last Lesson review:     1, c/s        client----- Server        Browser-----Server        which must have:            1, stable operation , has been providing services            to the outside 2, binding a fixed ip+port    2,        the Internet:2.1 Physical Connection Media         2.2  Internet Protocol (Internet Protocol i.e. English of computer interface)    3, TCP         three handshake         semi-connection pool backlog=5             Limit the number of requests at the same time, not the number         of connections Four waves to disconnect    today content:1, the software based on socket writing C/s architecture        based on TCP    protocol 2, TCP protocol sticky packet Problem

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Socket communication based on TCP protocol

ImportSocket#1. Buy Mobile phonePhone=socket.socket (Socket.af_inet,socket. SOCK_STREAM)#TCP is called a streaming protocol, and UDP is called Datagram Protocol Sock_dgram#print (phone)#2. Insert/bind Mobile card#phone.setsockopt (socket. Sol_socket,socket. so_reuseaddr,1)Phone.bind (('127.0.0.1', 8080))#3. BootPhone.listen (5)#semi-connection pool, limit the number of requests#4, waiting for the telephone connectionPrint('start ....') whileTrue:#Connecting LoopsConn,client_addr=phone.accept ()#(three-time handshake established two-way connection (client IP, port))    #PRINT (conn)    Print('there is already a connection established successfully', CLIENT_ADDR)#5. Communication: receiving \ Sending messages     whileTrue:#Communication Cycle        Try:            Print('service in the data collection ...') Data=CONN.RECV (1024)#The maximum number of bytes received, no data will be waiting in situ, that is, the amount of data sent by the sender must be >0bytes            #print (' ===> ')            ifLen (data) = = 0: Break #when the client unilaterally disconnects, the server will not receive the empty data            Print('data from the client', data) Conn.send (Data.upper ())exceptConnectionreseterror: Break    #6. Hang up the phone connectionconn.close ()#7. Shut down the machinePhone.close ()

Sever

ImportSocket#1. Buy Mobile phonePhone=Socket.socket (Socket.af_inet,socket. SOCK_STREAM)#print (phone)#2. Dial phonePhone.connect (('127.0.0.1', 8080))#specifying server-side IP and Ports#3, communication: send \ Receive Messages whileTrue:#Communication CycleMsg=input ('>>:'). Strip ()#msg= "    ifLen (msg) = = 0:Continuephone.send (Msg.encode ('Utf-8'))    #print (' has send-----> ')DATA=PHONE.RECV (1024)    #print (' has recv-----> ')    Print(data)#4. ClosePhone.close ()

Client

Access process application Layer data--os (protocol layer: port, plus TCP header, add IP header, find gateway Mac, binary number----network transport----Physical layer, data layer, network layer, Transport layer, application layer)

DNS: Horizontal recursive query for vertical iterative queries

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