Question

In Python, make changes in the client code, so that the client allows the user to continue to send multiple requests until the user types in “Quit”. This means that the client process should not exit after the user sends one request and receives one response. Instead, the client process should be able to receive subsequent inputs from the user. You need to have a loop in the client code, so that it can accept the user request until the user explicitly types in “Quit”.  Please comment on what each line does.

You are required to have files:

The modified UDP client code. (preferred file name: UDPClient.py)

The modified TCP client code. (preferred file name: TCPClient.py)

Python Socket Programming (using Python 3)

If we use UDP sockets, we have the following code:

Python code for the UDP client:

UDP client

from socket import *

serverName = 'localhost'

serverPort = 12000

clientSocket = socket(AF_INET, SOCK_DGRAM)

message = input("Input a lowercase sentence: ")

clientSocket.sendto(message.encode(), (serverName, serverPort))

modifiedMessage, serverAddress = clientSocket.recvfrom(2048)

print(modifiedMessage.decode())

clientSocket.close()

TCP client

from socket import *

serverName = 'localhost'

serverPort = 12000

clientSocket = socket(AF_INET, SOCK_STREAM)

clientSocket.connect((serverName, serverPort))

sentence = input("Input a lowercase sentence: ")

clientSocket.send(sentence.encode())

modifiedSentence = clientSocket.recv(1024)

print(modifiedSentence.decode())

clientSocket.close()

TCP clients to interact correctly with the given TCP server, your clients should also use a non-persistent implementation to send multiple requests to the server. This means that you should use a separate TCP connection to send each request from the user; if the user has multiple requests to send (which is an important requirement you need to implement), you should constantly open and close new TCP connections.

modified UDP client code

modified TCP client code

Answer 1

UDP Client:

Code:

# Import socket
from socket import *

# Server address
serverName = 'localhost'
# Server port number
serverPort = 12000

# Loop until user give Quit command
while True:
# Creating client socket
clientSocket = socket(AF_INET, SOCK_DGRAM)
# Get a lower case sentence from user
message = input("Input a lowercase sentence: ")
# If the input is Quit, then end the program
if message is "Quit":
break
# Otherwise send the message to server
clientSocket.sendto(message.encode(), (serverName, serverPort))
# Receive response from server
modifiedMessage, serverAddress = clientSocket.recvfrom(2048)
# Print the server response
print(modifiedMessage.decode())
# Close client socket
clientSocket.close()

Code screenshot:

# Import socket from socket import * # Server address serverName = 'localhost' # Server port number server Port = 12000 # Loop until user give Quit command while True: # Creating client socket client Socket = socket (AF_INET, SOCK_DGRAM) # Get a lower case sentence from user message = input ("Input a lowercase sentence: ") # If the input is Quit, then end the program if message is "Quit": break # Otherwise send the message to server client Socket.sendto (message. encode (), (serverName, serverPort)) # Receive response from server modifiedMessage, serverAddress = client Socket.recvfrom (2048) # Print the server response print (modifiedMessage.decode()) # Close client socket client Socket.close()

Output:

RESTART: C:\Users\Retheesh\Desktop\UDPClient.py Input a lowercase sentence: "hello" HELLO Input a lowercase sentence: Thai" HAI Input a lowercase sentence: "Quit" >>>|

TCP Client:

Code:

# Import socket
from socket import *

# Server address
serverName = 'localhost'
# Server port number
serverPort = 12000

# Loop until give Quit command
while True:
# Creating client socket
clientSocket = socket(AF_INET, SOCK_STREAM)
# Connecting with server
clientSocket.connect((serverName, serverPort))
# Get a lowercase sentence from user
sentence = input("Input a lowercase sentence: ")
# If inpt is Quit, then end the program
if sentence is "Quit":
break
# Otherwise sending the message to server
clientSocket.send(sentence.encode())
# Receiving message from server
modifiedSentence = clientSocket.recv(1024)
# Print the message from server
print(modifiedSentence.decode())
# Closing socket
clientSocket.close()

Code screenshot:

# Import socket from socket import * # Server address serverName = 'localhost' # Server port number server Port = 12000 # Loop until give Quit command while True: # Creating client socket client Socket = socket (AF_INET, SOCK_STREAM) # Connecting with server client Socket.connect((serverName, server Port)) # Get a lowercase sentence from user sentence = input ("Input a lowercase sentence: ") # If inpt is Quit, then end the program if sentence is "Quit": " break # Otherwise sending the message to server client Socket.send(sentence.encode()) # Receiving message from server modifiedSentence = client Socket.recv (1024) # Print the message from server print (modifiedSentence.decode()) # Closing socket client Socket.close()

Output:

===== ===== RESTART: C:\Users\Retheesh\Desktop\TCPClient.py Input a lowercase sentence: "hello" HELLO Input a lowercase sentence: "hai" HAI Input a lowercase sentence: "Quit" >>>

Additional Information:

UDP server code:

import socket

bufferSize = 1024

# Create a datagram socket
UDPServerSocket = socket.socket(family=socket.AF_INET, type=socket.SOCK_DGRAM)
#UDPServerSocket.close()
# Bind to address and ip
UDPServerSocket.bind(("127.0.0.1", 12001))

print("UDP server up and listening")

# Listen for incoming datagrams
while(True):
bytesAddressPair = UDPServerSocket.recvfrom(bufferSize)
message = bytesAddressPair[0]
address = bytesAddressPair[1]
clientMsg = "Message from Client:{}".format(message)
clientIP = "Client IP Address:{}".format(address)
print(clientMsg)
print(clientIP)

bytesToSend = str.encode(message.upper())
  
# Sending a reply to client
# UDPServerSocket.sendto(bytesToSend, address)
UDPServerSocket.sendto(bytesToSend, address)

UDP server code screenshot:

import socket buffer Size = 1024 # Create a datagram socket UDPServerSocket = socket.socket (family=socket. AF_INET, type=socket. SOCK_DGRAM) #UDPServer Socket.close() # Bind to address and ip UDPServerSocket.bind( ("127.0.0.1", 12001)) print ("UDP server up and listening") # Listen for incoming datagrams while (True): bytesAddress Pair = UDPServerSocket.recvfrom (bufferSize) message = bytesAddress Pair[0] address = bytesAddress Pair[1]|| clientMsg = "Message from Client:{}".Format (message) clientIP = "Client IP Address: {}". format (address) print (clientMsg) print (clientIP) bytesToSend = str.encode (message. upper()) # Sending a reply to client # UDPServerSocket.sendto (bytesToSend, address) UDPServerSocket.sendto (bytesToSend, address)

TCP server code:

import socket
import sys

# Create a TCP/IP socket
sock = socket.socket(family=socket.AF_INET, type=socket.SOCK_STREAM)

# Bind the socket to the port
sock.bind(('localhost', 12000))

# Listen for incoming connections
sock.listen(1)

while True:
# Wait for a connection
print >>sys.stderr, 'waiting for a connection'
connection, client_address = sock.accept()

try:
print >>sys.stderr, 'connection from', client_address

# Receive the data in small chunks and retransmit it
while True:
data = connection.recv(1024)
print >>sys.stderr, 'received "%s"' % data
if data:
print >>sys.stderr, 'sending data back to the client'
connection.sendall(data.upper())
else:
print >>sys.stderr, 'no more data from', client_address
break
  
finally:
# Clean up the connection
connection.close()

TCP server code screenshot:

import socket import sys # Create a TCP/IP socket sock = socket.socket (family=socket.AF_INET, type=socket. SOCK_STREAM) # Bind the socket to the port sock.bind(('localhost', 12000)) # Listen for incoming connections sock.listen (1) while True: # Wait for a connection print >>sys.stderr, "waiting for a connection connection, client_address = sock.accept() try: print >>sys.stderr, 'connection from', client_address # Receive the data in small chunks and retransmit it while True: data = connection.recv(1024) print >>sys.stderr, 'received "*"' $data if data: print >>sys.stderr, 'sending data back to the client' connection.sendall (data.upper()) else: print >>sys.stderr, 'no more data from', client_address break finally: # Clean up the connection connection.close |