This can be very useful for setting up **resources** that you need to use for the whole app, and that are **shared** among requests, and/or that you need to **clean up** afterwards. For example, a database connection pool, or loading a shared machine learning model.

## Use Case

Let's start with an example **use case** and then see how to solve it with this.

Let's imagine that you have some **machine learning models** that you want to use to handle requests. 🤖

     * extra state from AbstractFuture), our options are limited: A call to setException() would be
     * a no-op. We could log, but if that's what we really want, we should modify
     * AbstractFuture.executeListener to do so, since that method would have the ability to continue
     * to execute other listeners.
     *

[19515] [INFO] Application startup complete.
```

</div>

Let's see what each of those options mean:

* `main:app`: This is the same syntax used by Uvicorn, `main` means the Python module named "`main`", so, a file `main.py`. And `app` is the name of the variable that is the **FastAPI** application.
    * You can imagine that `main:app` is equivalent to a Python `import` statement like:

        ```Python

 * }
 * }</pre>
 *
 * The calls to {@link #isSubtype} and {@link #notSubtype} tells the framework what assertions need
 * to be made.
 *
 * <p>The declaration methods must be public.
 */
@AndroidIncompatible // only used by android incompatible tests.
abstract class SubtypeTester implements Cloneable {

  /** Annotates a public method that declares subtype assertion. */
  @RequiredModifiers(Modifier.PUBLIC)

It will use the default status code or the one you set in your *path operation*.

## Additional status codes

If you want to return additional status codes apart from the main one, you can do that by returning a `Response` directly, like a `JSONResponse`, and set the additional status code directly.

    // Verify the peer received what was expected.
    assertThat(peer.takeFrame().type).isEqualTo(Http2.TYPE_HEADERS)
    assertThat(peer.takeFrame().type).isEqualTo(Http2.TYPE_RST_STREAM)
  }

  /**
   * Confirm that the client times out if the server stalls after 3 bytes. After the timeout the
   * connection is still considered healthy while we await the degraded pong. When that doesn't

In this case, it would use the certificate for `someapp.example.com`.

<img src="/img/deployment/https/https03.svg">

The client already **trusts** the entity that generated that TLS certificate (in this case Let's Encrypt, but we'll see about that later), so it can **verify** that the certificate is valid.

## Details

The first `"/static"` refers to the sub-path this "sub-application" will be "mounted" on. So, any path that starts with `"/static"` will be handled by it.

The `directory="static"` refers to the name of the directory that contains your static files.

The `name="static"` gives it a name that can be used internally by **FastAPI**.

  // seLinux is the strategy that will dictate the allowable labels that may be set.
  optional SELinuxStrategyOptions seLinux = 10;

  // runAsUser is the strategy that will dictate the allowable RunAsUser values that may be set.
  optional RunAsUserStrategyOptions runAsUser = 11;

  // RunAsGroup is the strategy that will dictate the allowable RunAsGroup values that may be set.

# Security Tools

When you need to declare dependencies with OAuth2 scopes you use `Security()`.

But you still need to define what is the dependable, the callable that you pass as a parameter to `Depends()` or `Security()`.

There are multiple tools that you can use to create those dependables, and they get integrated into OpenAPI so they are shown in the automatic docs UI, they can be used by automatically generated clients and SDKs, etc.