FastAPI Architecture & ASGI Server (Uvicorn)

1Concept

FastAPI is a modern, high-performance web framework built on Starlette and Pydantic. It runs on the Asynchronous Server Gateway Interface (ASGI) standard via Uvicorn, automatically generating OpenAPI (Swagger) documentation at `/docs`.

2Architecture Diagram

HTTP Request ---> [ Uvicorn ASGI Server ] ---> [ Starlette Routing ] ---> [ Pydantic Validation ] ---> Endpoint

3Code Example

fastapi_app_code = '''
from fastapi import FastAPI

app = FastAPI(title="Enterprise API Gateway", version="1.0.0")

@app.get("/health")
async def health_check():
    return {"status": "HEALTHY", "version": "1.0.0"}

# Run with: uvicorn main:app --workers 4 --port 8000
'''
print("=== FastAPI Microservice Definition ===")
print(fastapi_app_code.strip())

4Expected Output

=== FastAPI Microservice Definition ===
from fastapi import FastAPI

app = FastAPI(title="Enterprise API Gateway", version="1.0.0")

@app.get("/health")
async def health_check():
    return {"status": "HEALTHY", "version": "1.0.0"}

# Run with: uvicorn main:app --workers 4 --port 8000

5Key Takeaways

• ✓FastAPI achieves performance on par with NodeJS and Go.
• ✓Interactive Swagger documentation is available at `/docs`; ReDoc is at `/redoc`.
• ✓Defines endpoints with `async def` for I/O operations and `def` for CPU tasks (dispatched to threadpool).