Understanding WebSockets

WebSockets establish a two-way communication channel over a persistent connection. Unlike conventional request-response architectures, where clients must wait for a server's reply, WebSockets empower both clients and servers to transmit messages independently.

To start using WebSockets in Python, you'll need to install the websockets library:

pip install websockets

Setting Up a WebSocket Server

Let's kick off by creating a basic WebSocket server. With just a few lines of code, you can have a server up and running:

import asyncio

import websockets

async def handle_connection(websocket, path):

while True:

message = await websocket.recv()

print(f"Received message: {message}")

await websocket.send(f"Echo: {message}")

start_server = websockets.serve(handle_connection, "localhost", 8765)

asyncio.get_event_loop().run_until_complete(start_server)

asyncio.get_event_loop().run_forever()

This code snippet creates a WebSocket server on localhost:8765 that echoes any received message. The handle_connection function manages the communication for each WebSocket connection.

Video Description: This video demonstrates how to utilize Python, Flask, and WebSockets for real-time updates in web applications.

Establishing a WebSocket Client Connection

With the server operational, let's write a Python script to connect to it. The websockets library simplifies this process:

import asyncio

import websockets

async def send_message():

uri = "ws://localhost:8765"

async with websockets.connect(uri) as websocket:

message = input("Enter a message: ")

await websocket.send(message)

response = await websocket.recv()

print(f"Server response: {response}")

asyncio.get_event_loop().run_until_complete(send_message())

This client script connects to the WebSocket server and sends a message, then prints the server's reply. Run both the server and client scripts to observe real-time communication in action.

Broadcasting Messages to Clients

Next, let's enhance our server to broadcast messages to all connected clients. Update your server code as follows:

import asyncio

import websockets

connected_clients = set()

async def handle_connection(websocket, path):

connected_clients.add(websocket)

try:

while True:

message = await websocket.recv()

print(f"Received message: {message}")

# Broadcast the message to all connected clients

for client in connected_clients:

await client.send(f"Broadcast: {message}")

finally:

# Remove the client upon disconnection

connected_clients.remove(websocket)

start_server = websockets.serve(handle_connection, "localhost", 8765)

asyncio.get_event_loop().run_until_complete(start_server)

asyncio.get_event_loop().run_forever()

Now, any message sent by a client will be relayed to all other connected clients, illustrating the power of WebSockets in crafting real-time interactive applications.

Handling Custom Events

WebSockets can also manage custom events. Let's modify our client script to handle these events:

import asyncio

import websockets

async def handle_events():

uri = "ws://localhost:8765"

async with websockets.connect(uri) as websocket:

while True:

message = await websocket.recv()

if message.startswith("Event:"):

event_data = message.split(":")[1].strip()

print(f"Event received: {event_data}")

asyncio.get_event_loop().run_until_complete(handle_events())

Next, update the server to send events:

async def handle_connection(websocket, path):

connected_clients.add(websocket)

try:

while True:

message = await websocket.recv()

print(f"Received message: {message}")

if message.startswith("Event:"):

# Broadcast the event to all connected clients

for client in connected_clients:

await client.send(message)

else:

# Broadcast regular messages

for client in connected_clients:

await client.send(f"Broadcast: {message}")

finally:

connected_clients.remove(websocket)

Now, any message beginning with "Event:" will be treated as a special event and broadcast accordingly.