Client-Server framework where one server will communicate with multiple clients
Description:
Client-server is a software architecture model consisting of two parts, client systems and server systems, both communicating over a computer network or on the same computer. A client-server application is a distributed system made up of both client and server software. Client server application provide a better way to share the workload.The client process always initiates a connection to the server, while the server process always waits for requests from any client.
For handling multiple clients , the concept of Threading is used here.
Explanation:
--socket(socket.AF_INET, socket.SOCK_STREAM):
AF_INET ia an address family that indicates the type of address that the socket can communicate with. AF_INET indicates ipv4 addresses. when a socket is creating it is necessary to specify the address family. linux kernel supports 29 other address families
SOCK_STREAM indicates that it is a TCP socket . for UDP we use SOCK_DGRAM
--setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1):
socket.SO_REUSEADDR, causes the port to be released immediately after the socket is closed so that it is re-usable.
SOL_SOCKET is the socket layer itself. It is used for options that are protocol independent
--socket.bind((hostname, port)):
Bind to a particular port in preparation to receive connections on this port. bind() takes one parameter, which is a two value tuple consisting of a hostname (string) and port number (integer).
--socket.accept():
Used for accepting a new connection. We can get the IP address and port number.
--socket.listen():
Tells the socket to listen for incoming connections
Implementation:
Server.py:
import socket
from threading import Thread
def client_thread(conn, ip, port):
#this is to check if client wants to exit or not
client_status = True
#loop runs untill client gives exit
while client_status:
#recieving the client request query and decoding as well as printing
data = conn.recv(1024)
message=data.decode()
print("message from "+ip+":"+port+">>",message)
#checking for exit in message for termination
if "exit" in message:
print("Connection " + ip + ":" + port + " closed")
conn.close()
#if exit set status to false to end listening loop
client_status = False
else:
#server reply to client
reply="hello , Message recieved: "+message
conn.sendall(reply.encode())
def main():
#set the host and port number
host = "127.0.0.1" #we can also use gethostname() or specify separately
port = 8888 # we can enter any other appropriate port
#creating a socket object for server
Server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
#making the port reusable in case of abrupt closing
Server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
#binding to the port
Server.bind((host, port))
#queue upto 3 requests
Server.listen(3)
print("Server is ready for requests")
# infinite loop- does not reset for every requests
while True:
#establishing new client connection
conn, address = Server.accept()
#extracting ip and port address of client
ip, port = str(address[0]), str(address[1])
print("Connected with client ")
print("ip: " + ip + " port:" + port)
try:
#creating thread to handle multiple clients
newclient = Thread(target=client_thread, args=(conn, ip, port))
newclient.start()
except:
print("Error executing thread.")
#closing the server
Server.close()
if __name__ == "__main__":
main()
Client.py:
import socket
import sys
def main():
#creating a socket object for client
Client1 = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
#setting host and port number
host = "127.0.0.1" #we can also use gethostname() or specify separately
port = 8888 # we can enter any other appropriate port
#connecting to server
try:
Client1.connect((host, port))
except:
print("Connection error")
sys.exit()
#taking input from client and sending to server untill client wants to terminate
print("Enter 'exit' to disconnect")
message = input(" >> ")
while message != 'exit':
#sending client data
Client1.send(message.encode())
#accepting server reply and printing it
#here it is accpeting data upto 1024 bytes. Can be increased for larger data
reply = Client1.recv(1024).decode()
print("SERVER >",reply)
message = input(" >> ")
#sending termination message for server
Client1.send(b'exit')
if __name__ == "__main__":
main()
Output:
Establishing connection with 2 clients:
Receiving client requests and responding back:
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