Python Falcon – WSGI vs ASGI

When developing web applications or APIs with Falcon, one crucial decision you’ll need to make is whether to use WSGI (Web Server Gateway Interface) or ASGI (Asynchronous Server Gateway Interface) as the communication protocol between Falcon and your web server. In this article, we’ll explore the differences between WSGI and ASGI and help you decide which one is the right choice for your Falcon application.

What is Python Falcon

Python Falcon is a lightweight web framework in Python. It is used for building high-performance APIs (Application Programming Interfaces). It is a minimalist ASGI/WSGI framework for building REST APIs with a focus on performance and reliability. In this article, we will look at the difference between WSGI vs ASGI

Some key features of Python Falcon:

1. Performance-oriented – Used in projects where speed and low latency are crucial, such as microservices and high-traffic APIs.
2. Minimalistic – This framework only provides the essential tools and features for building APIs. Not more than that.
3. HTTP-centric – Falcon is builtMinimalistic around HTTP protocols which makes developers think in terms of HTTP requests (GET, POST, DELETE, etc.).
4. Middleware support – This allows us to add custom processing to requests and responses.
5. WebSocket Support – This makes Falconis built suitable for applications requiring real-time and bidirectional communications.
6. ASGI / WSGI – Falcon supports both ASGI (Asynchronous Server Gateway Interface) and WSGI (Web Server Gateway Interface).
7. Well-documented – Falcon has comprehensive documentation and a Falconsupportive community.

When we have to handle HTTP requests and responses in Falcon, there are two different protocols –

1. WSGI – Web Server Gateway Interface
2. ASGI – Asynchronous Server Gateway Interface

WSGI (Web Server gate Interface)

WSGI is synchronous, which means it handles one request at a time. When a request comes in, it’s processed by the web server and the WSGI application sequentially. This makes it suitable for applications with low to moderate traffic.

Some key features of WSGI

1. Synchronous Processing
   • WSGI is a synchronous protocol, which means that it handles one request at a time.
   • Each incoming HTTP request is processed sequentially. In the meantime, it blocks the server until the processing is completed.
   • This limits the responsiveness and concurrency of the application, especially when we are dealing with long-running tasks.
2. Compatibility
   • WSGI is a traditional, and widely accepted interface for Python applications.
   • It is compatible with many web servers and hosting environments.
3. Simplicity
   • Writing code is pretty Straightforward and simple,
   • It is a good choice for small to medium APIs which can bring moderate size traffic.

Example

Python3

import falcon

# Create a Falcon application
app = falcon.App()

# Define a resource to handle requests
class HelloWorldResource:
    def on_get(self, req, resp):
        resp.status = falcon.HTTP_200
        resp.body = "Hello, WSGI World!"

# Add the resource to the application
app.add_route("/", HelloWorldResource())

# Run the application using a WSGI server (e.g., gunicorn)
# Install gunicorn with: pip install gunicorn
# Run with: gunicorn myapp:app
# OR
# Install waitress with: pip install waitress
# Run with: waitress-serve --host=0.0.0.0 --port=8000 filename:app

Code Explanation

We created a Flask WSGI application using “flask” module. This is a basic example just showing difference between WSGI and ASGI working.

1. Import the library using command
   • import flask.
   • Before that run command pip install flask in your terminal to install flask.
2. Create a falcon app
   • app = Flask(__name__)
   • This app object will be used to define routes and handle HTTP requests.
3. Defining a falcon resource class
   • class HelloWorldResouce is a resource class.
   • In python, resources are Python classes that handle http requests(GET POST PUT)
   • Here, “on_get” method is defined to handle GET requests.
   • When a GET request is received, it sets the response status to 200 (ok) and shows the response body with output “Hello WSGI World!” at localhost:8000.
4. Now, add this resource to your application:
   • app.add_route(“/”, HelloWorldResource())
   • This line executes the HelloWorldResource at root URL “/”.
   • When the GET request is made to the root URL “/”, Falcon will invoke on_get method of the HelloWorldResource class.
5. Final step is to run the application using some WSGI server.
   • Gunicorn – pip install gunicorn
     • Run the file and then type this command in your terminal
       • gunicorn filename:app
   • waitress – pip install waitress
     • Run the file and then type this command in your terminal
       • waitress-serve –host=0.0.0.0 –port=8000 filename:app
       • Your can choose any other port (here 8000)
6. Output of above code
   • The output of the above code will be visible at localhost:8000 or at port you chose.
   • This is the output screen.

Output

ASGI (Asynchronous Server Gateway Interface)

ASGI, or Asynchronous Server Gateway Interface, is a more recent standard that’s designed to handle asynchronous web applications and real-time communication more efficiently. It allows Falcon and other Python web frameworks to work with asynchronous web servers and take advantage of asynchronous programming techniques.

1. Synchronous Processing
   • ASGI is an asynchronous protocol, which means that it allows parallel processing of multiple requests.
   • It handles real-time, long-polling and Websocket connections efficiently.
2. Compatibility
   • ASGI is newer than WSGI.
   • This may require web servers and hosting environments that support ASGI, like Daphne, hypercorn or uvicorn.
3. Complex Use Cases
   • ASGI is ideal for complex and high traffic applications.
   • It is ideal for application processing in real time like chat applications, streaming services and live notifications.

Example

Python3

import falcon
app = falcon.App()
class HelloWorldResource:
    async def on_get(self, req, resp):
        resp.status = falcon.HTTP_200
        resp.text = "Hello, ASGI World!"
app.add_route("/", HelloWorldResource())

Code Explanation

1. Import the library using command
   • Falcon is used to create ASGI application and uvicorn is used to run the application.
2. Create a falcon app
   • app = falcon.app()
   • This app object will be used to define routes and handle HTTP requests.
3. Similar to WSGI code, we define a falcon resource class
   • class HelloWorldResouce is a resource class.
   • Resources are Python classes that handle http requests(GET, POST, PUT)
   • Here, “on_get” method is defined to handle GET requests.
   • When a GET request is received, it sets the response status to 200 (ok) and shows the response body with output “Hello ASGI World!” at localhost:8000.
4. Again similar to previous code, add this resource to your application:
   • app.add_route(“/”, HelloWorldResource())
   • This line executes the HelloWorldResource at root URL “/”.
   • When the GET request is made to the root URL “/”, Falcon will invoke on_get method of the HelloWorldResource class.
5. Finally, run the application using some ASGI server.
   • Run the file and then type this command in your terminal
     • uvicorn filename:app
   • Run the file and then type this command in your terminal
     • pip install waitress
     • waitress-serve –host=0.0.0.0 –port=8000 filename:app
     • Your can choose any other port (here 8000)
6. Output of above code
   • The output of the above code will be visible at localhost:8000 or at port you chose.
   • This is the output screen.

Output

Output of ASGI app at localhost:8000

How to choose between ASGI and WSGI with Falcon?

The choice depends on specific requirements of the application. For example , if we have a simple API with low to moderate traffic, and we want wide range compatibility, we can opt for WSGI. If we have a complex API with high traffic and application uses real-time features like Websocket, we must opt for ASGI. This way, we can handle simultaneous connections efficiently.

Difference Table WSGI vs ASGI

Characteristic	WSGI	ASGI
Full form	Web Server Gateway Interface	Asynchronous Server Gateway Interface
Synchronous Processing	Handles one request at a time	Allows parallel processing of multiple requests at a time
Blocking Behavior	Blocks the server until the processing of one request is completed.	Does not block the server
Compatibility	Traditional, so runs on mojority web servers and hosting environments	Newer protocol, so may require specific web servers and hosting environments
Usage	Used for simple and straightforward applications that use simple APIs with low to moderate traffic.	Used for complex and high traffic applications.
Example servers/hosts	waitress, gunicorn	waitress, uvicorn