* So, by using FastAPI you are saving development time, bugs, lines of code, and you would probably get the same performance (or better) you would if you didn't use it (as you would have to implement it all...

```Python hl_lines="9"
{!../../../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.

```Python hl_lines="11  14-16"
{!../../../docs_src/sub_applications/tutorial001.py!}
```

### Mount the sub-application

In your top-level application, `app`, mount the sub-application, `subapi`.

In this case, it will be mounted at the path `/subapi`:

```Python hl_lines="11  19"
{!../../../docs_src/sub_applications/tutorial001.py!}
```

And multiple processes normally **don't share any memory**. This means that each running process has its own things, variables, and memory. And if you are consuming a large amount of memory in your code, **each process** will consume an equivalent amount of memory.

### Server Memory

    This is because we want to include their *path operations* in the OpenAPI schema and the user interfaces.

    As we cannot just isolate them and "mount" them independently of the rest, the *path operations* are "cloned" (re-created), not included directly.

## Check the automatic API docs

Now, run `uvicorn`, using the module `app.main` and the variable `app`:

### Technische Details: `root_path`

Wenn Sie eine Unteranwendung wie oben beschrieben mounten, kümmert sich FastAPI darum, den Mount-Pfad für die Unteranwendung zu kommunizieren, mithilfe eines Mechanismus aus der ASGI-Spezifikation namens `root_path`.

### Tested

* 100% <abbr title="The amount of code that is automatically tested">test coverage</abbr>.
* 100% <abbr title="Python type annotations, with this your editor and external tools can give you better support">type annotated</abbr> code base.

### ♾ "🔌-🔌"

⚖️ 🎏 🌌, 🙅‍♂ 💪 👫, 🗄 & ⚙️ 📟 👆 💪.

🙆 🛠️ 🏗 🙅 ⚙️ (⏮️ 🔗) 👈 👆 💪 ✍ "🔌-" 👆 🈸 2️⃣ ⏸ 📟 ⚙️ 🎏 📊 & ❕ ⚙️ 👆 *➡ 🛠️*.

### 💯

* 1️⃣0️⃣0️⃣ 💯 <abbr title="The amount of code that is automatically tested">💯 💰</abbr>.
* 1️⃣0️⃣0️⃣ 💯 <abbr title="Python type annotations, with this your editor and external tools can give you better support">🆎 ✍</abbr> 📟 🧢.
* ⚙️ 🏭 🈸.

## 💃 ⚒

It would take the same amount of time to finish with or without turns (concurrency) and you would have done the same amount of work.

# 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`.