**FastAPI** provides the same `WebSocket` directly just as a convenience for you, the developer. But it comes directly from Starlette.

///

## Await for messages and send messages { #await-for-messages-and-send-messages }

In your WebSocket route you can `await` for messages and send messages.

{* ../../docs_src/websockets_/tutorial001_py310.py hl[48:52] *}

You can receive and send binary, text, and JSON data.

### Gérer les fichiers et async { #files-and-async }

Dans la plupart des cas, les objets de type fichier ne sont pas compatibles avec `async` et `await` par défaut.

Par exemple, ils n'ont pas de `await file.read()`, ni de `async for chunk in file`.

Et dans de nombreux cas, leur lecture serait une opération bloquante (pouvant bloquer la boucle d'événements), car ils sont lus depuis le disque ou le réseau.

```Python
with open("file.txt") as file:
    file.read()
```

Python’ın güncel sürümlerinde bir de **async context manager** vardır. Bunu `async with` ile kullanırsınız:

```Python
async with lifespan(app):
    await do_stuff()
```

* `seek(offset)`: Переходить до байтової позиції `offset` (`int`) у файлі.
    * Наприклад, `await myfile.seek(0)` перейде на початок файлу.
    * Це особливо корисно, якщо ви виконаєте `await myfile.read()` один раз, а потім потрібно знову прочитати вміст.
* `close()`: Закриває файл.

Оскільки всі ці методи є асинхронними `async` методами, вам потрібно їх «await»-ити.

/// note | Teknik Detaylar

Bir `async` görev, yalnızca bir `await` noktasına geldiğinde iptal edilebilir. Eğer hiç `await` yoksa, generator (içinde `yield` olan fonksiyon) düzgün şekilde iptal edilemez ve iptal istendikten sonra bile çalışmaya devam edebilir.

Bu küçük örneğin `await` ifadesine ihtiyacı olmadığı için, event loop’un iptali ele alabilmesi adına `await anyio.sleep(0)` ekliyoruz.

Büyük veya sonsuz akışlarda bu daha da önemlidir.

          }
        };
    waiter.start();
    service.startAsync().awaitRunning();
    assertEquals(State.RUNNING, service.state());
    service.stopAsync();
    waiter.join(LONG_TIMEOUT_MILLIS); // ensure that the await in the other thread is triggered
    assertFalse(waiter.isAlive());
  }

  public void testAwaitTerminated_failedService() throws Exception {
    ManualSwitchedService service = new ManualSwitchedService();

          }
        };
    waiter.start();
    service.startAsync().awaitRunning();
    assertEquals(State.RUNNING, service.state());
    service.stopAsync();
    waiter.join(LONG_TIMEOUT_MILLIS); // ensure that the await in the other thread is triggered
    assertFalse(waiter.isAlive());
  }

  public void testAwaitTerminated_failedService() throws Exception {
    ManualSwitchedService service = new ManualSwitchedService();

          @Override
          protected void finalize() {
            latch.countDown();
          }
        };
    unused = null; // Hint to the JIT that unused is unreachable
    GcFinalization.await(latch);
    assertEquals(0, latch.getCount());
  }

  public void testAwaitDone_future() {
    SettableFuture<@Nullable Void> future = SettableFuture.create();
    Object unused =
        new Object() {

expected"));if(s.hooks&&(s.hooks.options=s,s.hooks.block=e),s.async)return(async()=>{let o=s.hooks?await s.hooks.preprocess(n):n,p=await(s.hooks?await s.hooks.provideLexer():e?x.lex:x.lexInline)(o,s),c=s.hooks?await s.hooks.processAllTokens(p):p;s.walkTokens&&await Promise.all(this.walkTokens(c,s.walkTokens));let h=await(s.hooks?await s.hooks.provideParser():e?b.parse:b.parseInline)(c,s);return s.hooks?await s.hooks.postprocess(h):h})().catch(a);try{s.hooks&&(n=s.hooks.preprocess(n));let u=(s.hooks?s...

import time

from fastapi import FastAPI, Request

app = FastAPI()


@app.middleware("http")
async def add_process_time_header(request: Request, call_next):
    start_time = time.perf_counter()
    response = await call_next(request)
    process_time = time.perf_counter() - start_time
    response.headers["X-Process-Time"] = str(process_time)