* And then they need to be **renewed**, **acquired again** from the third party.
* The encryption of the connection happens at the **TCP level**.
    * That's one layer **below HTTP**.
    * So, the **certificate and encryption** handling is done **before HTTP**.
* **TCP doesn't know about "domains"**. Only about IP addresses.
    * The information about the **specific domain** requested goes in the **HTTP data**.

👆 👀 👈 👆 💪 ⚙️ 🔗 ⏮️ `yield` & ✔️ `try` 🍫 👈 ✊ ⚠.

⚫️ 5️⃣📆 😋 🤚 `HTTPException` ⚖️ 🎏 🚪 📟, ⏮️ `yield`. ✋️ **⚫️ 🏆 🚫 👷**.

🚪 📟 🔗 ⏮️ `yield` 🛠️ *⏮️* 📨 📨, [⚠ 🐕‍🦺](../handling-errors.md#_4){.internal-link target=_blank} 🔜 ✔️ ⏪ 🏃. 📤 🕳 😽 ⚠ 🚮 👆 🔗 🚪 📟 (⏮️ `yield`).

, 🚥 👆 🤚 `HTTPException` ⏮️ `yield`, 🔢 (⚖️ 🙆 🛃) ⚠ 🐕‍🦺 👈 ✊ `HTTPException`Ⓜ & 📨 🇺🇸🔍 4️⃣0️⃣0️⃣ 📨 🏆 🚫 📤 ✊ 👈 ⚠ 🚫🔜.

from fastapi.testclient import TestClient

from docs_src.handling_errors.tutorial002 import app

client = TestClient(app)


def test_get_item_header():
    response = client.get("/items-header/foo")
    assert response.status_code == 200, response.text
    assert response.json() == {"item": "The Foo Wrestlers"}


def test_get_item_not_found_header():
    response = client.get("/items-header/bar")

## Mounting a **FastAPI** application

"Mounting" means adding a completely "independent" application in a specific path, that then takes care of handling everything under that path, with the _path operations_ declared in that sub-application.

### Top-level application

First, create the main, top-level, **FastAPI** application, and its *path operations*:

        * [Install custom exception handlers](https://fastapi.tiangolo.com/tutorial/handling-errors/#install-custom-exception-handlers).
        * [Override the default exception handlers](https://fastapi.tiangolo.com/tutorial/handling-errors/#override-the-default-exception-handlers).
        * [Re-use **FastAPI's** exception handlers](https://fastapi.tiangolo.com/tutorial/handling-errors/#re-use-fastapis-exception-handlers).

⏮️ 👈, 🌐 🏭 ⚛ 🎏.

✋️ ↩️ 👆 🔀 `GzipRequest.body`, 📨 💪 🔜 🔁 🗜 🕐❔ ⚫️ 📐 **FastAPI** 🕐❔ 💪.

## 🔐 📨 💪 ⚠ 🐕‍🦺

!!! tip
    ❎ 👉 🎏 ⚠, ⚫️ 🎲 📚 ⏩ ⚙️ `body` 🛃 🐕‍🦺 `RequestValidationError` ([🚚 ❌](../tutorial/handling-errors.md#requestvalidationerror){.internal-link target=_blank}).

    ✋️ 👉 🖼 ☑ & ⚫️ 🎦 ❔ 🔗 ⏮️ 🔗 🦲.

👥 💪 ⚙️ 👉 🎏 🎯 🔐 📨 💪 ⚠ 🐕‍🦺.

🌐 👥 💪 🍵 📨 🔘 `try`/`except` 🍫:

```Python hl_lines="13  15"

The main constraint to consider is that there has to be a **single** component handling the **port** in the **public IP**. And then it has to have a way to **transmit** the communication to the replicated **processes/workers**.

Here are some possible combinations and strategies:

│       ├── __init__.py  # makes "internal" a "Python subpackage"
│       └── admin.py     # "admin" submodule, e.g. import app.internal.admin
```

## `APIRouter`

Let's say the file dedicated to handling just users is the submodule at `/app/routers/users.py`.

You want to have the *path operations* related to your users separated from the rest of the code, to keep it organized.

## Recap

With what you have seen up to now, you can set up a secure **FastAPI** application using standards like OAuth2 and JWT.

In almost any framework handling the security becomes a rather complex subject quite quickly.

## Use o `HTTPException`

Para retornar ao cliente *responses* HTTP com erros, use o `HTTPException`.

### Import `HTTPException`

```Python hl_lines="1"
{!../../../docs_src/handling_errors/tutorial001.py!}
```

### Lance o `HTTPException` no seu código.

`HTTPException`, ao fundo, nada mais é do que a conjunção entre uma exceção comum do Python e informações adicionais relevantes para APIs.