How to Make a Chat Room Application in Python?

In a Chat Room Application, two or more clients connected to the server and chat with each other. The server fetches the messages from one client and shares them with other clients so all the clients could communicate with each other.

To build a Chat Room in Python we need to create only two scripts. The first script will be the server script that will handle all the messages from the clients and broadcast the messages and the second script would be the client script, which will be used by clients to connect with the server and send messages.

In this tutorial, I will be using my local system as a server which means my server would be the localhost, and all the clients will also run locally on this system. Before we implement our Chat Room using Python let's discuss the modules we will be using in this tutorial.

Required Modules

For this tutorial, we will be using two Python standard libraries.

Python socket

socket is one of the Python inbuilt modules, and it is widely used to perform socket programming in Python. Using the socket modules we can set the connection between two nodes network. For this tutorial, we will use socket programming to set server and clients and communicate them with each other.

Python threading

Python threading module is used to simulate multi-threading in Python. Although actually Python does not support multi-threading because of GIL lock, but threading module allows us to simulate the execution of threads concurrently.

Both the modules socket and threading are available for Python so we do not need to install them separately. Now let's start coding our server and client scripts.

Server Script with Python

First, we need to write our Python server script, that will handle all the clients and broadcast(share) message amongst them. In our server script, we will create three modules:

• broadcast_message() will share messages amongst all the connected clients.
• message_manager() will receive messages from the clients.
• connection() will manage both the messages and show the connected clients.

Now let's start coding the server script We will begin with importing the required modules.

import socket
import threading

HOST = '127.0.0.1'   #localhost
PORT = 50000  # anyport

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

server.bind((HOST, PORT))
server.listen()   #listen incoming connection

clients = []
client_names =[]

def broadcast_message(message):
    for client in clients:
        client.send(message)

def message_manager(client):
    while True:
        try:
            message = client.recv(1024)   # receive  the message
            broadcast_message(message) 
        except:
            index = clients.index(client)
            clients.remove(client)
            client.close()
            client_name = client_names[index]
            print(f"Client {client_name} Disconnected!".encode('ascii'))
            client_names.remove(client_name)
            break

Now let's define the connection() function that will handle the complete server by running the clients and their messages in different threads.

def connection():
    while True:
        client, address =server.accept()
        print(f"{address} Connected[+]")
        client.send("UserName".encode('ascii'))
        client_name =client.recv(1024).decode('ascii')

        client_names.append(client_name)
        clients.append(client)

        print(f"{client_name} Connected[+]")  #on server
        message = f"{client_name} Connected[+]".encode('ascii')   
        broadcast_message(message)       #send message to every client

        client.send("You are connected to server".encode('ascii'))

        thread = threading.Thread(target=message_manager, args=(client,))
        thread.start()

print("Server[127.0.0.1] localhost is running.... ")
connection()

Python Server Program for Chat Room

#server.py

import socket
import threading

HOST = '127.0.0.1'   #localhost
PORT = 50000  # anyport 

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

server.bind((HOST, PORT))
server.listen()   #listen incoming connection

clients = []
client_names =[]

def broadcast_message(message):
    for client in clients:
        client.send(message)

def message_manager(client):
    while True:
        try:
            message = client.recv(1024)   # receive  the message
            broadcast_message(message) 
        except:
            index = clients.index(client)
            clients.remove(client)
            client.close()
            client_name = client_names[index]
            print(f"Client {client_name} Disconnected!".encode('ascii'))
            client_names.remove(client_name)
            break

def connection():
    while True:
        client, address =server.accept()
        print(f"{address} Connected[+]")
        client.send("UserName".encode('ascii'))
        client_name =client.recv(1024).decode('ascii')

        client_names.append(client_name)
        clients.append(client)

        print(f"{client_name} Connected[+]")  #on server
        message = f"{client_name} Connected[+]".encode('ascii')   
        broadcast_message(message)       #send message to every client

        client.send("You are connected to server".encode('ascii'))

        thread = threading.Thread(target=message_manager, args=(client,))
        thread.start()

print("Server[127.0.0.1] localhost is running.... ")
connection()

Client Script with Python

We have done with the Server script, now we need to write the client script that will be used by the client to connect with the server, send and read messages. I have divided the client script into two major modules:

• read_messages() will receive the messages from the server.
• write_message() will send the messages to the server.

In our client script, we first need to import the required modules and set the connection for the localhost and port number on which our server script is running.

import socket
import threading

HOST = '127.0.0.1'   
PORT = 50000  

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

client.connect((HOST, PORT))
username= input("Please Enter a User Name: ")

Now let's define a function read_message() that will read or print all the messages on the terminal sent from other users and also send the Entered username to the server for when the client connected to the server for the first time.

def read_message():
    while True:
        try:
            message = client.recv(1204).decode('ascii')    #receive messgae from server
            if message =="UserName":
                client.send(username.encode('ascii'))
            else:
                print(message)
        except:
            print("Error!")
            client.close()
            break

client.recv(1204).decode('ascii') will receive the message from the server. The send(username.encode('ascii')) will send the Entered username to the server if the message is encoded to Username or when the user connected to the server for the very first time.

The try block will show the message if everything goes well if the client closes its terminal or left the server the except block close the client using close() function. Now let's create a write_message() function that will help the user to write and send messages to the server.

def write_message():
    while True:
        message = f"{username}: {input(': ')}"
        client.send(message.encode("ascii"))     #send message to server

The send() function will send the encoded message to the severe. Now we need to call the read_message() and write_message() function using threads so multiple users can send the messages concurrently, instead of one after another.

read_thread = threading.Thread(target=read_message)
read_thread.start()

write_thread = threading.Thread(target=write_message)
write_thread.start()

import socket
import threading

HOST = '127.0.0.1'   
PORT = 50000  

client = socket.socket(socket.AF_INET, socket.SOCK_STREAM) 
client.connect((HOST, PORT))
username= input("Please Enter a User Name: ")

def read_message():
    while True:
        try:
            message = client.recv(1204).decode('ascii')    #receive messgae from server
            if message =="UserName":
                client.send(username.encode('ascii'))
            else:
                print(message)
        except:
            print("Error!")
            client.close()
            break
                
def write_message():
    while True:
        message = f"{username}: {input(': ')}"
        client.send(message.encode("ascii"))     #send message to server

read_thread = threading.Thread(target=read_message)
read_thread.start()

write_thread = threading.Thread(target=write_message)
write_thread.start()

Output

To see the output you can open three terminals or command prompts, out of which one needs to be the server and the other two could be clients. Do not execute the client.py script before the server.py script always executes the server first. When you execute the server script on one terminal and two clients script on two other terminals you will be able to create a Chat room.

Conclusion

Now let's sum up the above article. To create a chat room in Python you need to create two different scripts one for the server and another for the client. To set the communication between the server and client we use Python socket programming along with multi-threading, so there would no lag between the message send and message read. You can copy and paste the above two scripts, run them on your local machine and it would work as expected.

Here in this article, I have used the LocalHost to set the server and clients, if you have a dedicated server or router on which you want to set the server, you only need to change the HOST address and the PORT number.

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