import java.lang.annotation.Target;

/**
 * The annotated element must not be null.
 * <p>
 * Annotated fields must not be null after construction has completed.
 * <p>
 * When this annotation is applied to a method it applies to the method return value.
 *
 * @see Nullable
 * @since 4.0.0
 */
@Experimental
@Documented
@Retention(RetentionPolicy.CLASS)

* <a href="https://hub.docker.com/_/postgres" class="external-link" target="_blank">PostgreSQL</a>
* <a href="https://hub.docker.com/_/mysql" class="external-link" target="_blank">MySQL</a>
* <a href="https://hub.docker.com/_/mongo" class="external-link" target="_blank">MongoDB</a>
* <a href="https://hub.docker.com/_/redis" class="external-link" target="_blank">Redis</a>, etc.

            target /= 1024;
            target /= 1024;
            target /= 1024;
            unit = "G";
        } else {
            target /= 1024;
            target /= 1024;
            target /= 1024;
            target /= 1024;
            unit = "T";
        }
        final DecimalFormat df = (DecimalFormat) NumberFormat.getNumberInstance(getUserLocale());

![Swagger UI interaction](https://fastapi.tiangolo.com/img/index/index-03-swagger-02.png)

* Une autre documentation d'API est fournie par <a href="https://github.com/Rebilly/ReDoc" class="external-link" target="_blank"><strong>ReDoc</strong></a>.

* <a href="https://cdn.jsdelivr.net/npm/swagger-ui-dist@5/swagger-ui.css" class="external-link" target="_blank">`swagger-ui.css`</a>

And **ReDoc** uses the file:

* <a href="https://cdn.jsdelivr.net/npm/redoc@next/bundles/redoc.standalone.js" class="external-link" target="_blank">`redoc.standalone.js`</a>

# Including WSGI - Flask, Django, others

You can mount WSGI applications as you saw with [Sub Applications - Mounts](sub-applications.md){.internal-link target=_blank}, [Behind a Proxy](behind-a-proxy.md){.internal-link target=_blank}.

For that, you can use the `WSGIMiddleware` and use it to wrap your WSGI application, for example, Flask, Django, etc.

## Using `WSGIMiddleware`

You need to import `WSGIMiddleware`.

/// check

, ⏮️ 🎏 🐍 🆎 📄, **FastAPI** 🤝 👆 💽 🔬.

👀 👈 ❌ 🎯 🇵🇸 ⚫️❔ ☝ 🌐❔ 🔬 🚫 🚶‍♀️.

👉 🙃 👍 ⏪ 🛠️ & 🛠️ 📟 👈 🔗 ⏮️ 👆 🛠️.

///

## 🧾

&amp; 🕐❔ 👆 📂 👆 🖥 <a href="http://127.0.0.1:8000/docs" class="external-link" target="_blank">http://127.0.0.1:8000/docs</a>, 👆 🔜 👀 🏧, 🎓, 🛠️ 🧾 💖:

/// tip

The next sections are **not necessarily "advanced"**.

And it's possible that for your use case, the solution is in one of them.

///

## Read the Tutorial first

The next sections assume you already read the main [Tutorial - User Guide: Security](../../tutorial/security/index.md){.internal-link target=_blank}.

### Sprawdź to

Otwórz w swojej przeglądarce <a href="http://127.0.0.1:8000" class="external-link" target="_blank">http://127.0.0.1:8000</a>.

Zobaczysz odpowiedź w formacie JSON:

```JSON
{"message": "Hello World"}
```

### Interaktywna dokumentacja API

Przejdź teraz do <a href="http://127.0.0.1:8000/docs" class="external-link" target="_blank">http://127.0.0.1:8000/docs</a>.

Попередні скріншоти були зроблені у <a href="https://code.visualstudio.com" class="external-link" target="_blank">Visual Studio Code</a>.

Але ви отримаєте ту саму підтримку редактора у <a href="https://www.jetbrains.com/pycharm/" class="external-link" target="_blank">PyCharm</a> та більшість інших редакторів Python:

<img src="/img/tutorial/body/image05.png">

/// tip