#!Nonblocking I/O - Chapter 5 -pollclient.py

 import socket,sys,select

 port=51423

 host='localhost'

 spinsize=10

 spinpos=0

 spindir=1

 def spin():

     global spinsize,spinpos,spindir

     spinstr='.'*spinpos+'|'+'.'*(spinsize-spinpos-1)

     sys.stdout.write('\r'+spinstr+'  ')

     sys.stdout.flush()

     spinpos+=spindir

     if spinpos<0:

         spindir=1

         spinpos=1

     elif spinpos>=spinsize:

         spinpos-=2

         spindir=-1

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

 sock.connect((host,port))

 p=select.poll()

 p.register(sock.fileno(),select.POLLIN|select.POLLERR|select.POLLHUP)

 while True:

     results=p.poll(2002)

     if len(results):

         if results[0][1]==select.POLLIN:

             data=sock.recv(4096).decode()

             if not len(data):

                 print("\rRemote end closed connection; exiting.")

                 break

         sys.stdout.write("\rReceived :"+data)

         sys.stdout.flush()

         spin()

     else:

         print("\rProblem occurred; exiting")

         sys.exit(0)

 #!Delaying Server - Chapter 5 -delayserver.py

 import socket,traceback,time

 host=""

 port=51423

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

 sock.setsockopt(socket.SOL_SOCKET,socket.SO_REUSEADDR,1)

 sock.bind((host,port))

 sock.listen(1)

 while True:

     try:

         clientsock,clientaddr= sock.accept()

     except KeyboardInterrupt:

         raise

     except:

         traceback.print_exc()

         continue

     try:

         print("Got connection from ",clientsock.getpeername)

         while True:

             try:

                 print(time.asctime().encode())

                 clientsock.sendall(time.asctime().encode()+b"\n")

             except:

                 break

             time.sleep(2)

     except (KeyboardInterrupt,SystemExit):

         raise

     except:

         traceback.print_exc()

     try:

         clientsock.close()

     except KeyboardInterrupt:

         raise

     except:

         traceback.print_exc()