```Python hl_lines="2  7  9"
{!../../../docs_src/custom_response/tutorial006c.py!}
```

### `StreamingResponse`

Nimmt einen asynchronen Generator oder einen normalen Generator/Iterator und streamt den Responsebody.

```Python hl_lines="2  14"
{!../../../docs_src/custom_response/tutorial007.py!}
```

 *
 * ```java
 * Call call = client.newCall(request);
 * try (Response response = call.execute()) {
 * ... // Use the response.
 * }
 * ```
 *
 * You can use a similar block for asynchronous calls:
 *
 * ```java
 * Call call = client.newCall(request);
 * call.enqueue(new Callback() {
 *   public void onResponse(Call call, Response response) throws IOException {

{!../../../docs_src/first_steps/tutorial001.py!}
```

C'est une fonction Python.

Elle sera appelée par **FastAPI** quand une requête sur l'URL `/` sera reçue via une opération `GET`.

Ici, c'est une fonction asynchrone (définie avec `async def`).

---

Vous pourriez aussi la définir comme une fonction classique plutôt qu'avec `async def` :

```Python hl_lines="7"
{!../../../docs_src/first_steps/tutorial003.py!}
```

   * calls returns to zero).
   *
   * Note: The time at which a [call][Call] is considered idle is different depending on whether it
   * was run [asynchronously][Call.enqueue] or [synchronously][Call.execute]. Asynchronous calls
   * become idle after the [onResponse][Callback.onResponse] or [onFailure][Callback.onFailure]
   * callback has returned. Synchronous calls become idle once [execute()][Call.execute] returns.

```Python hl_lines="1"
async def get_burgers(number: int):
    # Do some asynchronous stuff to create the burgers
    return burgers
```

...`def`를 사용하는 대신:

```Python hl_lines="2"
# This is not asynchronous
def get_sequential_burgers(number: int):
    # Do some sequential stuff to create the burgers
    return burgers
```

  }

  @Test
  fun networkInterceptorThrowsRuntimeExceptionAsynchronous() {
    interceptorThrowsRuntimeExceptionAsynchronous(true)
  }

  /**
   * When an interceptor throws an unexpected exception, asynchronous calls are canceled. The
   * exception goes to the uncaught exception handler.
   */
  private fun interceptorThrowsRuntimeExceptionAsynchronous(network: Boolean) {
    val boom = RuntimeException("boom!")

Here's a little bit of that history.

## Alternatives

I have been creating APIs with complex requirements for several years (Machine Learning, distributed systems, asynchronous jobs, NoSQL databases, etc), leading several teams of developers.

As part of that, I needed to investigate, test and use many alternatives.

The history of **FastAPI** is in great part the history of its predecessors.

!!! tip "Tipp"
    Wenn Sie in Ihren Tests neben dem Senden von Anfragen an Ihre FastAPI-Anwendung auch `async`-Funktionen aufrufen möchten (z. B. asynchrone Datenbankfunktionen), werfen Sie einen Blick auf die [Async-Tests](../advanced/async-tests.md){.internal-link target=_blank} im Handbuch für fortgeschrittene Benutzer.

## Tests separieren

  /** http://tools.ietf.org/html/draft-ietf-httpbis-http2-17#section-5.1.1 */
  internal var nextStreamId = if (builder.client) 3 else 2

  private var isShutdown = false

  /** For scheduling everything asynchronous. */
  private val taskRunner = builder.taskRunner

  /** Asynchronously writes frames to the outgoing socket. */
  private val writerQueue = taskRunner.newQueue()

      this.routeDatabase = okHttpClient.routeDatabase
      this.taskRunner = okHttpClient.taskRunner
    }

    /**
     * Sets the dispatcher used to set policy and execute asynchronous requests. Must not be null.
     */
    fun dispatcher(dispatcher: Dispatcher) =
      apply {
        this.dispatcher = dispatcher
      }

    /**