WSGI

WSGI stands for Web Server Gateway Interface. It's a standard interface between web servers and Python web applications or frameworks. It allows you to write web applications in Python that can run on any WSGI-compatible web server.

🔧 How it works (high-level)

• The web server (e.g., Gunicorn, uWSGI) receives an HTTP request.
• It forwards the request to your Python app via a WSGI interface.
• Your Python app returns a response (status, headers, body) through the WSGI interface.
• The server sends the response back to the client.

📄 WSGI Application Example

def application(environ, start_response):
    status = '200 OK'
    headers = [('Content-Type', 'text/plain')]
    start_response(status, headers)
    return [b"Hello, World!"]

• environ: A dict with request info (method, path, headers, etc.)
• start_response: A function used to send status and headers to the server

✅ Why WSGI is useful

• Standardizes the way Python web apps and servers communicate
• Lets you run frameworks like Flask, Django, or FastAPI (via ASGI fallback) on WSGI servers
• Enables switching between servers without changing your app

🔄 WSGI vs ASGI

• WSGI: Synchronous (traditional apps like Django, Flask)
• ASGI: Asynchronous + synchronous (supports WebSockets, long polling – for FastAPI, Django Channels)