Client-Server Chat Room using Python

2021-11-17 1222 words 6 minutes

Contents

Client-Server Chat Room

In my previous article, I covered what a socket is and the different types of sockets, as well as the C implementation. Today, we’ll use Sockets to create a client-server chat room in Python.

Let’s look at how client-server architecture works first. The client-server architecture is a model in which the server hosts, provides, and controls the majority of the resources and services that the client consumes. One or more client computers are connected to a central server through a network or the internet in this architecture.

In our programme, we will create a basic server that will wait for a client to connect and then receive the messages from client and send it to other clients in the server. When someone disconnected then it broadcast the message that the particular client is disconnected.

Let’s Dive into Coding!

Server Side Coding

We need to import the necessary packages

# File : Server.py

import socket 
# to establish connection between server and client

import threading 
# to run multiple tasks at same time

Create socket object

# server.py continue....

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

socket.AF_INET to define Address family
- AF_INET for IPv4
- AF_INET6 for IPv6
socket.SOCK_STREAM to define type of socket
- SOCK_STREAM for TCP/IP
- SOCK_DGRAM for UDP
- See all other types and their Information here

Define Veriables for easy to use

# server.py continue....

ADDRESS = '127.0.0.1'
PORT = 5550

ADDRESS variable defines the address that we want to host our server
- we are building this for local area network LAN
- so we are specifying local host address which is 127.0.0.1
PORT to host on 5550 port
why not other ports?
- 0 to 1024 ports are well known and predefined for services
- You can see more info here on which port you want to use
- you can use any port above 1024

Bind the server to address and port [means hosting the server on ADDRESS and PORT]

# server.py continue....

server.bind((ADDRESS,PORT))

bind() assign an IP address and port to the server instance
- bind() function needed tuple of address and port

Now, before start listening and accepting the clients. we need to define some functions to organize and simplify the code

# server.py continue....

clients = []
names = []

def broadcast(messege):
  for client in clients:
    client.send(message.encode('utf-8')

creating list called clients and names
- to store the IP addresses of connected clients
- and there names
defined a function called broadcast()
- take messege as parameter
- in every client in list of clients
- send the messege in encoded form
- Why? because sockets talk each other in bytes

Create function for revcieve and broadcast that revcived messege

# server.py continue....

def recv_messege_send(client):
  while True:
    try:
       msg = client.recv(1024).decode('utf-8')
       broadcast(msg)
    except:
       index = clients.index(client)
       nm = names[index]
       print(f"{nm} left the server!")
       clients.remove(client)
       broadcast(f"{nm} left the server!")
       names.remove(nm)
       client.close()
       break

defined a function called recv_send()
- which take client as an parameter then
- try to check any messeage from the client and broadcast the messege
- if any error occurs
  - error like client is left the server
  - client is down
- then take index of that client and remove it from clients list and from names list
- then broadcast the messeage that the particular client is left the server
- close() for closing the connection of that client and break the loop so that server
  - we won’t recive any messege from that removed client anymore

We’re good to go now for listen the clients

# server.py continue....

server.listen(5)

while True: #0
    client,addr = server.accept() #1
    print(f"{addr} is Connected to the server!") #2
    broadcast(f"{addr} is Connected to the server!") #3
    client.send('NAME'.encode('utf-8')) #4
    nm = client.recv(1024).decode('utf-8') #5
    broadcast(f"Name of {addr} is {nm}") #6
    print(f"Name of {addr} is {nm}") #7
    clients.append(client) #8 
    names.append(nm) #9
    rec = threading.Thread(target=recv_messege_send,args=(client,)) #10
    rec.start() #11

server.listen() to listen the client is trying to connect
- listen() function have parameter value 5
- which means server listening upto 5 clients
- You increase number of clients you want to connect to the server
Running a loop
- at #1 to accept the clients who wants to connect to the server
- at #1 in client,addr client store the information of the connected client and addr take only address of connected client
- at #2 and #3 to simply just broadcast the messege that the client is connected
- at #4 asking the client to enter his nickname to display in server
- at #5 to #9 reciving the name of that connected client decodeing it and storing in veriable then broadcasting the messege to tell the connected clients the name of the new connected client and then adding the new connected client address in clients list and name in names list

at #10 we are using threading concept

threading means running multiple functions,tasks at same time
so in that Thread function we targeting the function recv_messege_send with client as an argument
so when the server waiting for the client to connect at that same time server is receving the messege from other clients which are already connected to the server and broadcast that messege
at #11 we are starting that thread

Client side coding

We need to import the necessary packages

# File : client.py

import socket 
# to establish connection between server and client

import threading 
# to run multiple tasks at same time

Take Name to display on the server

# client.py continue....

name = input("Enter your name: ")

Defining Address and port which we want to connect

# client.py continue....

ADDRESS = '127.0.0.1'
PORT = 5550

Create Socket Object

# client.py continue....

client = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
try: 
    client.connect((ADDR,PORT)) #1
except:
    print("Server is Curruntly Down! or Unreachable!") #2
    exit()

socket.AF_INET to define Address family
- AF_INET for IPv4
- AF_INET6 for IPv6
socket.SOCK_STREAM to define type of socket
- SOCK_STREAM for TCP/IP
- SOCK_DGRAM for UDP
- See all other types and their Information here
NOTE: The address family and the type of socket must be same as server’s address family and socket type
at #1 we are trying to connect to the server
- if any error occurs like server is not running or anything else
- then printing the messege “Server is Curruntly Down! or Unreachable!” and exit the program

Creating simple function to send the messege to the server

# client.py continue....

def send_msg(client):
  while True:
      try:
          msg = input()
          client.send(f"{name}: {msg}".encode('utf-8'))
      except:
          print("Something Went Wrong")
          exit()

send_msg take client as an argument then run a while loop to take input from user and send that message with clients name and messege
if any error occurs then print “Something Went Wrong” and exit the program

Creating simple loop to recive and able to run the send_msg function at same time

# client.py continue....

while True:
    rec = client.recv(1024).decode('utf-8') #1
    if rec == 'NAME': #2
        client.send(name.encode('utf-8'))
    elif not rec: #3
        continue
    elif rec: #4
        print(f"{rec}")
    sm = threading.Thread(target=send_msg,args=(client,)) #5
    sm.start() #6

at #1 client receiving the messege from server and storing it in the rec
at #2 if messege received from the server contain ‘NAME’ which is asking for clients name then sending the name
at #3 if messege received from the server doesn’t contain any data then continue without printing it because server has no data to tell something
at #4 any messege is received from the server then simply print it
at #5 we are defining Thread Function to take send_msg function and run this function at same time as client is receving the messege
at #6 simply starting that thread

Contents

Client-Server Chat Room using Python

Client-Server Chat Room

Server Side Coding

Client side coding

Testing