`from starlette.websockets import WebSocket`을 사용할 수도 있습니다.

**FastAPI**는 개발자를 위한 편의를 위해 동일한 `WebSocket`을 직접 제공합니다. 하지만 이는 Starlette에서 가져옵니다.

///

## 메시지를 대기하고 전송하기 { #await-for-messages-and-send-messages }

WebSocket 경로에서 메시지를 대기(`await`)하고 전송할 수 있습니다.

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

여러분은 이진 데이터, 텍스트, JSON 데이터를 받을 수 있고 전송할 수 있습니다.

## 시도해보기 { #try-it }

/// note | Nota Técnica

Una tarea `async` solo puede cancelarse cuando llega a un `await`. Si no hay `await`, el generador (función con `yield`) no se puede cancelar correctamente y puede seguir ejecutándose incluso después de solicitar la cancelación.

Como este pequeño ejemplo no necesita ninguna sentencia `await`, añadimos un `await anyio.sleep(0)` para darle al loop de eventos la oportunidad de manejar la cancelación.

import pytest

from docs_src.async_tests.app_a_py310.test_main import test_root


@pytest.mark.anyio
async def test_async_testing():

}

func (r *RingBuffer) write(p []byte) (n int, err error) {
	if r.isFull {
		return 0, ErrIsFull
	}

	var avail int
	if r.w >= r.r {
		avail = r.size - r.w + r.r
	} else {
		avail = r.r - r.w
	}

	if len(p) > avail {
		err = ErrTooMuchDataToWrite
		p = p[:avail]
	}
	n = len(p)

	if r.w >= r.r {
		c1 := r.size - r.w
		if c1 >= n {
			copy(r.buf[r.w:], p)
			r.w += n

            executorService.submit(
                () -> {
                  startLatch.countDown();
                  startLatch.await();
                  callable.call();
                  doneLatch.countDown();
                  return null;
                });
      }
      doneLatch.await();
    } finally {
      executorService.shutdown();
    }
  }

        original_route_handler = super().get_route_handler()

        async def custom_route_handler(request: Request) -> Response:
            before = time.time()
            response: Response = await original_route_handler(request)
            duration = time.time() - before
            response.headers["X-Response-Time"] = str(duration)
            print(f"route duration: {duration}")

      // SequentialExecutor by the time the barrier is satisfied
      barrier.await(1, SECONDS);
      executor.execute(barrierTask);
      // timeout means the second task wasn't even tried
      barrier.await(1, SECONDS);
    } finally {
      service.shutdown();
    }
  }

  public void testRejectedExecutionThrownWithMultipleCalls() throws Exception {

/// note | Technische Details

Ein `async`-Task kann nur abgebrochen werden, wenn er ein `await` erreicht. Wenn es kein `await` gibt, kann der Generator (Funktion mit `yield`) nicht ordnungsgemäß abgebrochen werden und könnte weiterlaufen, selbst nachdem der Abbruch angefordert wurde.

Da dieses kleine Beispiel keine `await`-Anweisungen benötigt, fügen wir ein `await anyio.sleep(0)` hinzu, um dem Event Loop die Chance zu geben, den Abbruch zu verarbeiten.

/// note | Technical Details

An `async` task can only be cancelled when it reaches an `await`. If there is no `await`, the generator (function with `yield`) can not be cancelled properly and may keep running even after cancellation is requested.

Since this small example does not need any `await` statements, we add an `await anyio.sleep(0)` to give the event loop a chance to handle cancellation.

///

## Étapes préalables avant de démarrer { #previous-steps-before-starting }

Il existe de nombreux cas où vous souhaitez effectuer certaines étapes **avant de démarrer** votre application.

Par exemple, vous pourriez vouloir exécuter des **migrations de base de données**.