# Sample code for Multi-Threaded Server
#Python 3
# Usage: python3 UDPserver3.py
#coding: utf-8
from socket import *
import threading
import time
import datetime as dt
#Server will run on this port
serverPort = 12000
t_lock=threading.Condition()
#will store clients info in this list
clients=[]
# would communicate with clients after every second
UPDATE_INTERVAL= 1
timeout=False
def recv_handler():
global t_lock
global clients
global clientSocket
global serverSocket
print(‘Server is ready for service’)
while(1):
message, clientAddress = serverSocket.recvfrom(2048)
#received data from the client, now we know who we are talking with
message = message.decode()
#get lock as we might me accessing some shared data structures
with t_lock:
currtime = dt.datetime.now()
date_time = currtime.strftime(“%d/%m/%Y, %H:%M:%S”)
print(‘Received request from’, clientAddress[0], ‘listening at’, clientAddress[1], ‘:’, message, ‘at time ‘, date_time)
if(message == ‘Subscribe’):
#store client information (IP and Port No) in list
clients.append(clientAddress)
serverMessage=”Subscription successfull”
elif(message==’Unsubscribe’):
#check if client already subscribed or not
if(clientAddress in clients):
clients.remove(clientAddress)
serverMessage=”Subscription removed”
else:
serverMessage=”You are not currently subscribed”
else:
serverMessage=”Unknown command, send Subscribe or Unsubscribe only”
#send message to the client
serverSocket.sendto(serverMessage.encode(), clientAddress)
#notify the thread waiting
t_lock.notify()
def send_handler():
global t_lock
global clients
global clientSocket
global serverSocket
global timeout
#go through the list of the subscribed clients and send them the current time after every 1 second
while(1):
#get lock
with t_lock:
for i in clients:
currtime =dt.datetime.now()
date_time = currtime.strftime(“%d/%m/%Y, %H:%M:%S”)
message=’Current time is ‘ + date_time
clientSocket.sendto(message.encode(), i)
print(‘Sending time to’, i[0], ‘listening at’, i[1], ‘at time ‘, date_time)
#notify other thread
t_lock.notify()
#sleep for UPDATE_INTERVAL
time.sleep(UPDATE_INTERVAL)
#we will use two sockets, one for sending and one for receiving
clientSocket = socket(AF_INET, SOCK_DGRAM)
serverSocket = socket(AF_INET, SOCK_DGRAM)
serverSocket.setsockopt(SOL_SOCKET, SO_REUSEADDR, 1)
serverSocket.bind((‘localhost’, serverPort))
recv_thread=threading.Thread(name=”RecvHandler”, target=recv_handler)
recv_thread.daemon=True
recv_thread.start()
send_thread=threading.Thread(name=”SendHandler”,target=send_handler)
send_thread.daemon=True
send_thread.start()
#this is the main thread
while True:
time.sleep(0.1)