Python Flask Websocket: A Comprehensive Guide for Beginners

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Introduction

Python is a popular programming language that has been widely adopted by developers across the globe. It is a versatile language that can be used for various applications, including web development, data analysis, artificial intelligence, and more. One of the popular web frameworks in Python is Flask. Flask is a lightweight and flexible web framework that allows developers to build web applications quickly and easily. In this article, we will explore how to use Flask to create websockets using Python.

What is a Websocket?

A websocket is a protocol that enables real-time communication between a client and a server. It is a two-way communication protocol that allows the server to push data to the client without the client having to request it. Websockets are commonly used in web applications that require real-time updates, such as online gaming, chat applications, and financial trading platforms.

What is Flask?

Flask is a micro web framework written in Python. It is a lightweight and flexible framework that allows developers to build web applications quickly and easily. Flask provides a simple and intuitive API that makes it easy to get started with web development in Python. Flask is also highly extensible, which means that developers can easily add new functionality to their applications using third-party libraries.

How to Install Flask?

Before we dive into creating websockets with Flask, we need to install Flask on our system. To install Flask, we need to have Python and pip installed on our system. Once we have Python and pip installed, we can use pip to install Flask. Here are the steps to install Flask:

Open the terminal or command prompt.
Type the following command to install Flask:

pip install Flask

Press Enter to execute the command.

Wait for the installation to complete.

Creating a Flask Application

Now that we have installed Flask, we can start creating our Flask application. Here are the steps to create a Flask application:

Create a new directory for your Flask application.
Navigate to the directory using the terminal or command prompt.
Create a new Python file with the name app.py.
Open the app.py file in your favorite text editor.
Add the following code to the app.py file:

from flask import Flask
app = Flask(__name__)
@app.route(“/”)
def index():
return “Hello, World!”
if __name__ == “__main__”:
app.run(debug=True)

Save the app.py file.

The above code creates a new Flask application with a single route. When the user navigates to the root URL (i.e., “/”), the application returns a “Hello, World!” message. We can run the Flask application by executing the app.py file using the command prompt or terminal. Here are the steps to run the Flask application:

Open the terminal or command prompt.
Navigate to the directory where the app.py file is located.
Type the following command to run the Flask application:

python app.py

Press Enter to execute the command.

Wait for the Flask application to start.

Open a web browser and navigate to the URL “http://localhost:5000/”.

You should see the “Hello, World!” message displayed in the web browser.

What is a Socket?

A socket is an endpoint of a two-way communication link between two programs running on a network. A socket is identified by an IP address and a port number. Sockets are commonly used in computer networking to establish connections between different devices, such as servers, clients, and routers.

What is a Websocket Server?

A websocket server is a program that listens for websocket connections from clients and handles the communication between the clients and the server. The websocket server uses the websocket protocol to establish and maintain the connection between the clients and the server.

How to Create a Websocket Server Using Flask?

Now that we have a basic understanding of websockets, Flask, and sockets, we can start creating our websocket server using Flask. Here are the steps to create a websocket server using Flask:

Add the following code to the app.py file:

from flask_socketio import SocketIO, emit
app = Flask(__name__)
app.config[‘SECRET_KEY’] = ‘secret!’
socketio = SocketIO(app)
@app.route(‘/’)
def index():
return render_template(‘index.html’)
@socketio.on(‘connect’)
def test_connect():
print(‘Client connected’)
@socketio.on(‘disconnect’)
def test_disconnect():
print(‘Client disconnected’)
@socketio.on(‘message’)
def handle_message(message):
print(‘received message: ‘ + message)
emit(‘response’, message)

Create a new file with the name index.html in the templates folder.

Add the following code to the index.html file:

<!DOCTYPE html>
<html>
<head>
<title>Flask Websocket Example</title>
</head>
<body>
<script src=”https://cdnjs.cloudflare.com/ajax/libs/socket.io/2.3.1/socket.io.js”></script>
<script>
var socket = io.connect(‘http://’ + document.domain + ‘:’ + location.port);
socket.on(‘connect’, function() {
console.log(‘Connected’);
});
socket.on(‘response’, function(data) {
console.log(data);
});
socket.send(‘Hello, World!’);
</script>
</body>
</html>

Save the index.html file.

The above code creates a new Flask application with a websocket server. The websocket server listens for connections from clients and handles the communication between the clients and the server. When a client connects to the server, the server prints a message to the console. When a client sends a message to the server, the server prints the message to the console and sends a response back to the client.

The index.html file contains the client-side code that connects to the websocket server and sends a message to the server. When the server sends a response back to the client, the client prints the response to the console.

We can run the Flask application by executing the app.py file using the command prompt or terminal. Here are the steps to run the Flask application:

Open the terminal or command prompt.
Navigate to the directory where the app.py file is located.
Type the following command to run the Flask application:

python app.py

Press Enter to execute the command.

Wait for the Flask application to start.

Open a web browser and navigate to the URL “http://localhost:5000/”.

You should see a blank page displayed in the web browser.

Open the developer console in your web browser.

You should see the message “Connected” printed in the console.

The server should also print the message “Client connected” to the console.

Type a message in the console and press Enter.

You should see the message you typed displayed in the console, along with the response from the server.

Conclusion

In this article, we explored how to use Flask to create websockets using Python. We learned about websockets, Flask, sockets, and how to create a websocket server using Flask. We also learned how to install Flask, create a Flask application, and run a Flask application. We hope this article has provided you with a better understanding of websockets and Flask, and how to use them to create real-time web applications.

FAQs

What is Python Flask?

Python Flask is a micro web framework written in Python. It is a lightweight and flexible framework that allows developers to build web applications quickly and easily.

What is a Websocket?

What is a Socket?

A socket is an endpoint of a two-way communication link between two programs running on a network. A socket is identified by an IP address and a port number.