Specifically, to see Uvicorn, Starlette and FastAPI compared together (among many other tools).

The simpler the problem solved by the tool, the better performance it will get. And most of the benchmarks don't test the additional features provided by the tool.

The hierarchy is like:

* **Uvicorn**: an ASGI server
    * **Starlette**: (uses Uvicorn) a web microframework

                """
            ),
        ] = None,
        auto_error: Annotated[
            bool,
            Doc(
                """
                By default, if the HTTP Basic authentication is not provided (a
                header), `HTTPBasic` will automatically cancel the request and send the
                client an error.

                If `auto_error` is set to `False`, when the HTTP Basic authentication

    "root_path": "/api/v1"
}
```

but this time at the URL with the prefix path provided by the proxy: `/api/v1`.

Of course, the idea here is that everyone would access the app through the proxy, so the version with the path prefix `/api/v1` is the "correct" one.

And the version without the path prefix (`http://127.0.0.1:8000/app`), provided by Uvicorn directly, would be exclusively for the _proxy_ (Traefik) to access it.

                """
            ),
        ] = None,
        auto_error: Annotated[
            bool,
            Doc(
                """
                By default, if no HTTP Authorization header is provided, required for
                OAuth2 authentication, it will automatically cancel the request and
                send the client an error.

These features are what Marshmallow was built to provide. It is a great library, and I have used it a lot before.

But it was created before there existed Python type hints. So, to define every <abbr title="the definition of how data should be formed">schema</abbr> you need to use specific utils and classes provided by Marshmallow.

!!! check "Inspired **FastAPI** to"
    Use code to define "schemas" that provide data types and validation, automatically.

```

### Interactive API docs

Now go to <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 interactive API documentation (provided by <a href="https://github.com/swagger-api/swagger-ui" class="external-link" target="_blank">Swagger UI</a>):

![Swagger UI](https://fastapi.tiangolo.com/img/index/index-01-swagger-ui-simple.png)

### Alternative API docs

# WebSockets

When defining WebSockets, you normally declare a parameter of type `WebSocket` and with it you can read data from the client and send data to it.

It is provided directly by Starlette, but you can import it from `fastapi`:

```python
from fastapi import WebSocket
```

!!! tip

      "url": "https://errors.pydantic.dev/2.1/v/int_parsing"
    }
  ]
}
```

because the path parameter `item_id` had a value of `"foo"`, which is not an `int`.

The same error would appear if you provided a `float` instead of an `int`, as in: <a href="http://127.0.0.1:8000/items/4.2" class="external-link" target="_blank">http://127.0.0.1:8000/items/4.2</a>

!!! check

# Generate Clients

As **FastAPI** is based on the OpenAPI specification, you get automatic compatibility with many tools, including the automatic API docs (provided by Swagger UI).

One particular advantage that is not necessarily obvious is that you can **generate clients** (sometimes called <abbr title="Software Development Kits">**SDKs**</abbr> ) for your API, for many different **programming languages**.

## OpenAPI Client Generators

def test_users_token_monica_with_no_jessica(client: TestClient):
    response = client.get("/users?token=monica")
    assert response.status_code == 400
    assert response.json() == {"detail": "No Jessica token provided"}


def test_items_token_jessica(client: TestClient):
    response = client.get(
        "/items?token=jessica", headers={"X-Token": "fake-super-secret-token"}
    )
    assert response.status_code == 200