🌱 WSGI vs ASGI, Uvicorn & Middleware: Let's Learn from ZERO!

If you've built (or are building) a React + FastAPI project, you've probably run a command like this without thinking much about it:

python -m uvicorn app.main:app --reload --port 8000

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But what actually happens when a request travels from your React frontend to your Python backend? 🤔

In this post, we'll learn step by step, with no prior knowledge required :

✅ WSGI vs ASGI

✅ Synchronous vs Asynchronous web servers

✅ The ASGI spec's minimal 3-callable interface ( scope , receive , send )

✅ Uvicorn as an ASGI server

✅ ASGI middleware

Let's go! 🎉

1. 🖼️ The Big Picture

Imagine you open Instagram and click on a post.…