З цієї причини FastAPI також надає альтернативну документацію API (використовуючи ReDoc), до якої можна отримати доступ за посиланням <a href="http://127.0.0.1:8000/redoc" class="external-link" target="_blank">http://127.0.0.1:8000/redoc</a>:

本例没有实现回调本身（只是一行代码），只有文档部分。

/// tip | 提示

实际的回调只是 HTTP 请求。

实现回调时，要使用 <a href="https://www.encode.io/httpx/" class="external-link" target="_blank">HTTPX</a> 或 <a href="https://requests.readthedocs.io/" class="external-link" target="_blank">Requests</a>。

///

## 编写回调文档代码

应用不执行这部分代码，只是用它来*记录 外部 API* 。

但，您已经知道用 **FastAPI** 创建自动 API 文档有多简单了。

## Kurulum

<div class="termy">

```console
$ pip install fastapi

---> 100%
```

</div>

* <a href="https://github.com/encode/uvicorn/blob/master/uvicorn/middleware/proxy_headers.py" class="external-link" target="_blank">Uvicorn's `ProxyHeadersMiddleware`</a>
* <a href="https://github.com/florimondmanca/msgpack-asgi" class="external-link" target="_blank">MessagePack</a>

And open the docs at <a href="http://127.0.0.1:8000/docs" class="external-link" target="_blank">http://127.0.0.1:8000/docs</a>.

You will see the automatic API docs for the main app, including only its own _path operations_:

<img src="/img/tutorial/sub-applications/image01.png">

And then, open the docs for the sub-application, at <a href="http://127.0.0.1:8000/subapi/docs" class="external-link" target="_blank">http://127.0.0.1:8000/subapi/docs</a>.

    This will (let's imagine) let the API user (some external developer) create an
    invoice.

    And this path operation will:

    * Send the invoice to the client.
    * Collect the money from the client.
    * Send a notification back to the API user (the external developer), as a callback.
        * At this point is that the API will somehow send a POST request to the
            external API with the notification of the invoice event

///

## More info { #more-info }

To learn more about the options, check Starlette's documentation for:

* <a href="https://www.starlette.dev/websockets/" class="external-link" target="_blank">The `WebSocket` class</a>.

**Typer** є молодшим братом FastAPI. І це **FastAPI для CLI**. ⌨️ 🚀

## Вимоги

FastAPI стоїть на плечах гігантів:

* <a href="https://www.starlette.dev/" class="external-link" target="_blank">Starlette</a> для web частини.
* <a href="https://docs.pydantic.dev/" class="external-link" target="_blank">Pydantic</a> для частини даних.

La simplicidad del sistema de inyección de dependencias hace que **FastAPI** sea compatible con:

* todas las bases de datos relacionales
* bases de datos NoSQL
* paquetes externos
* APIs externas
* sistemas de autenticación y autorización
* sistemas de monitoreo de uso de la API
* sistemas de inyección de datos de response
* etc.

## Simple y Poderoso { #simple-and-powerful }

///

## Mais informações { #more-info }

Para aprender mais sobre as opções, verifique a documentação do Starlette para:

* <a href="https://www.starlette.dev/websockets/" class="external-link" target="_blank">A classe `WebSocket`</a>.