Le programme **serveur** (par exemple **Uvicorn** via **FastAPI CLI**) est capable d'interpréter ces en‑têtes, puis de transmettre ces informations à votre application.

Mais, par sécurité, comme le serveur ne sait pas qu'il se trouve derrière un proxy de confiance, il n'interprétera pas ces en‑têtes.

Notez que vous n’avez pas à créer une classe spéciale et à la passer quelque part à **FastAPI** pour l’« enregistrer » ou quoi que ce soit de similaire.

Vous la passez simplement à `Depends` et **FastAPI** sait faire le reste.

///

## Partager des dépendances `Annotated` { #share-annotated-dependencies }

Dans les exemples ci-dessus, vous voyez qu’il y a un tout petit peu de **duplication de code**.

Used by Starlette:

* [`httpx`](https://www.python-httpx.org) - Required if you want to use the `TestClient`.
* [`jinja2`](https://jinja.palletsprojects.com) - Required if you want to use the default template configuration.

Use `async` *path operations* only when fully certain that the logic called inside is compatible with async and await (it's called with `await`) or that doesn't block.

```python
from fastapi import FastAPI

app = FastAPI()


# Use async def when calling async code
@app.get("/async-items/")
async def read_async_items():
    data = await some_async_library.fetch_items()
    return data

    service.startAsync().awaitRunning();
    for (int i = 1; i < 10; i++) {
      service.runFirstBarrier.await();
      assertEquals(i, service.numberOfTimesRunCalled.get());
      service.runSecondBarrier.await();
    }
    service.runFirstBarrier.await();
    service.stopAsync();
    service.runSecondBarrier.await();
    service.stopAsync().awaitTerminated();
  }

    service.startAsync().awaitRunning();
    for (int i = 1; i < 10; i++) {
      service.runFirstBarrier.await();
      assertEquals(i, service.numberOfTimesRunCalled.get());
      service.runSecondBarrier.await();
    }
    service.runFirstBarrier.await();
    service.stopAsync();
    service.runSecondBarrier.await();
    service.stopAsync().awaitTerminated();
  }

@app.websocket("/function-scope")
async def function_scope(websocket: WebSocket, session: SessionFuncDep) -> Any:
    await websocket.accept()
    await websocket.send_json({"is_open": session.open})


@app.websocket("/request-scope")
async def request_scope(websocket: WebSocket, session: SessionRequestDep) -> Any:
    await websocket.accept()
    await websocket.send_json({"is_open": session.open})


@app.websocket("/two-scopes")

# Eşzamanlılık ve async / await { #concurrency-and-async-await }

*path operasyon fonksiyonları* için `async def` sözdizimi hakkında detaylar ve asenkron kod, eşzamanlılık (concurrency) ve paralellik üzerine arka plan bilgisi.

## Aceleniz mi var? { #in-a-hurry }

<abbr title="too long; didn't read - çok uzun; okumadım"><strong>TL;DR:</strong></abbr>

Eğer `await` ile çağırmanız gerektiğini söyleyen üçüncü taraf kütüphaneler kullanıyorsanız, örneğin:

pkg os, method (*PathError) Error() string
pkg os, method (*Process) Kill() error
pkg os, method (*Process) Release() error
pkg os, method (*Process) Signal(Signal) error
pkg os, method (*Process) Wait() (*ProcessState, error)
pkg os, method (*ProcessState) Exited() bool
pkg os, method (*ProcessState) Pid() int
pkg os, method (*ProcessState) String() string
pkg os, method (*ProcessState) Success() bool

):
    await websocket.accept()
    while True:
        data = await websocket.receive_text()
        await websocket.send_text(
            f"Session cookie or query token value is: {cookie_or_token}"
        )
        if q is not None:
            await websocket.send_text(f"Query parameter q is: {q}")