---

Des exemples communs d'opérations "CPU bounds" sont les procédés qui requièrent des traitements mathématiques complexes.

Par exemple :

* Traitements d'**audio** et d'**images**.

    response = client.get(
        "/items/bar?token=jessica", headers={"X-Token": "fake-super-secret-token"}
    )
    assert response.status_code == 404
    assert response.json() == {"detail": "Item not found"}


def test_items_plumbus_with_no_token(client: TestClient):
    response = client.get(
        "/items/plumbus", headers={"X-Token": "fake-super-secret-token"}
    )
    assert response.status_code == 422

    response = client.get(
        "/items/bar?token=jessica", headers={"X-Token": "fake-super-secret-token"}
    )
    assert response.status_code == 404
    assert response.json() == {"detail": "Item not found"}


@needs_py39
def test_items_plumbus_with_no_token(client: TestClient):
    response = client.get(
        "/items/plumbus", headers={"X-Token": "fake-super-secret-token"}
    )

Right before deciding to build **FastAPI** I found **APIStar** server. It had almost everything I was looking for and had a great design.

It was one of the first implementations of a framework using Python type hints to declare parameters and requests that I ever saw (before NestJS and Molten). I found it more or less at the same time as Hug. But APIStar used the OpenAPI standard.

```JSON
{
  "item": "The Foo Wrestlers"
}
```

しかし、クライアントが`http://example.com/items/bar`（存在しない`item_id` `"bar"`）をリクエストした場合、HTTPステータスコード404（"not found"エラー）と以下のJSONレスポンスが返されます:

```JSON
{
  "detail": "Item not found"
}
```

!!! tip "豆知識"
    `HTTPException`を発生させる際には、`str`だけでなく、JSONに変換できる任意の値を`detail`パラメータとして渡すことができます。

    `dist`や`list`などを渡すことができます。

{!../../../docs_src/behind_a_proxy/tutorial004.py!}
```

and then it won't include it in the OpenAPI schema.

## Mounting a sub-application

If you need to mount a sub-application (as described in [Sub Applications - Mounts](sub-applications.md){.internal-link target=_blank}) while also using a proxy with `root_path`, you can do it normally, as you would expect.

 │  🐍 main.py          │
 │                      │
 ╰──────────────────────╯

<font color="#3465A4">INFO    </font> Importing module <font color="#4E9A06">main</font>
<font color="#3465A4">INFO    </font> Found importable FastAPI app

 ╭─ <font color="#8AE234"><b>Importable FastAPI app</b></font> ─╮
 │                          │

            logging.error(log_message)
            raise RuntimeError(log_message)
        discussion = lang_to_discussion_map[lang]
        logging.info(
            f"Found a translation discussion for language: {lang} in discussion: #{discussion.number}"
        )

        already_notified_comment: Union[Comment, None] = None
        already_done_comment: Union[Comment, None] = None

```

Dann wird er nicht in das OpenAPI-Schema aufgenommen.

## Mounten einer Unteranwendung

Wenn Sie gleichzeitig eine Unteranwendung mounten (wie beschrieben in [Unteranwendungen – Mounts](sub-applications.md){.internal-link target=_blank}) und einen Proxy mit `root_path` verwenden wollen, können Sie das normal tun, wie Sie es erwarten würden.

}
```

Aber wenn der Client `http://example.com/items/bar` anfragt (ein nicht-existierendes `item_id` `"bar"`), erhält er einen HTTP-Statuscode 404 (der „Not Found“-Fehler), und eine JSON-Response wie folgt:

```JSON
{
  "detail": "Item not found"
}
```

!!! tip "Tipp"