#### API "schema"

In this case, <a href="https://github.com/OAI/OpenAPI-Specification" class="external-link" target="_blank">OpenAPI</a> is a specification that dictates how to define a schema of your API.

This schema definition includes your API paths, the possible parameters they take, etc.

#### Data "schema"

The term "schema" might also refer to the shape of some data, like a JSON content.

This is normally called a **webhook**.

## Webhooks steps

The process normally is that **you define** in your code what is the message that you will send, the **body of the request**.

You also define in some way at which **moments** your app will send those requests or events.

And **your users** define in some way (for example in a web dashboard somewhere) the **URL** where your app should send those requests.

    * Because pydantic data structures are just instances of classes you define; auto-completion, linting, mypy and your intuition should all work properly with your validated data.
* Validate **complex structures**:
    * Use of hierarchical Pydantic models, Python `typing`’s `List` and `Dict`, etc.
    * And validators allow complex data schemas to be clearly and easily defined, checked and documented as JSON Schema.

* **Cloud services** that handle this for you
    * The cloud service will probably **handle replication for you**. It would possibly let you define **a process to run**, or a **container image** to use, in any case, it would most probably be **a single Uvicorn process**, and the cloud service would be in charge of replicating it.

!!! tip

```

</div>

If you use Hypercorn, it also has the option `--root-path`.

!!! note "Technical Details"
    The ASGI specification defines a `root_path` for this use case.

    And the `--root-path` command line option provides that `root_path`.

### Checking the current `root_path`

Here we define the config `env_file` inside of your Pydantic `Settings` class, and set the value to the filename with the dotenv file we want to use.

### Creating the `Settings` only once with `lru_cache`

* 🐛 Fix FastAPI People GitHub Action: set HTTPX timeout for GraphQL query request. PR [#5222](https://github.com/tiangolo/fastapi/pull/5222) by [@iudeen](https://github.com/iudeen).
* 🐛 Make sure a parameter defined as required is kept required in OpenAPI even if defined as optional in another dependency. PR [#4319](https://github.com/tiangolo/fastapi/pull/4319) by [@cd17822](https://github.com/cd17822).

<div class="termy">

```console
$ pip install -r requirements.txt
---> 100%
Successfully installed fastapi pydantic
```

</div>

!!! info
    There are other formats and tools to define and install package dependencies.

### Create the **FastAPI** Code

* Create an `app` directory and enter it.
* Create an empty file `__init__.py`.
* Create a `main.py` file with:

```Python

    You can use a closing code from the <a href="https://tools.ietf.org/html/rfc6455#section-7.4.1" class="external-link" target="_blank">valid codes defined in the specification</a>.

### Try the WebSockets with dependencies

If your file is named `main.py`, run your application with:

<div class="termy">

```console
$ fastapi dev main.py