And then, that system (in this case **FastAPI**) will take care of doing whatever is needed to provide your code with those needed dependencies ("inject" the dependencies).

This is very useful when you need to:

* Have shared logic (the same code logic again and again).

## Mounting a **FastAPI** application { #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 { #top-level-application }

        with:
          # For discussion, see the first setup-java block.
          # The publish-snapshot workflow doesn't run tests, so we don't have to care which version Maven would select for that step.
          java-version: 24
          distribution: 'temurin'
          server-id: sonatype-nexus-snapshots
          server-username: CI_DEPLOY_USERNAME

///

### What is "Mounting" { #what-is-mounting }

"Mounting" means adding a complete "independent" application in a specific path, that then takes care of handling all the sub-paths.

This is different from using an `APIRouter` as a mounted application is completely independent. The OpenAPI and docs from your main application won't include anything from the mounted application, etc.

        if (value instanceof Entity) {
            data.register(key, BeanUtil.copyBeanToNewMap(value));
        } else {
            if (value instanceof final Collection<?> coll && !coll.isEmpty()) {
                // care performance for List that the most frequent pattern
                final Object first = coll instanceof List<?> ? ((List<?>) coll).get(0) : coll.iterator().next();
                if (first instanceof Entity) {

From the list of deployment concepts from above, using workers would mainly help with the **replication** part, and a little bit with the **restarts**, but you still need to take care of the others:

* **Security - HTTPS**
* **Running on startup**
* ***Restarts***
* Replication (the number of processes running)
* **Memory**
* **Previous steps before starting**

    ]
}
```

## Recap { #recap }

Declare headers with `Header`, using the same common pattern as `Query`, `Path` and `Cookie`.

And now, we can use `__init__` to declare the parameters of the instance that we can use to "parameterize" the dependency:

{* ../../docs_src/dependencies/tutorial011_an_py39.py hl[9] *}

In this case, **FastAPI** won't ever touch or care about `__init__`, we will use it directly in our code.

## Create an instance { #create-an-instance }

We could create an instance of this class with:

{* ../../docs_src/dependencies/tutorial011_an_py39.py hl[18] *}

    val timeout: Int = 180,
    val maxParallelForks: Int = 4,
) {
    // Include cross version tests, these take care of selecting a very small set of versions to cover when run as part of this stage, including the current version
    QUICK(true, true, true, 120, 4),

    // Include cross version tests, these take care of selecting a very small set of versions to cover when run as part of this stage, including the current version

# Sub-dependencies { #sub-dependencies }

You can create dependencies that have **sub-dependencies**.

They can be as **deep** as you need them to be.

**FastAPI** will take care of solving them.

## First dependency "dependable" { #first-dependency-dependable }

You could create a first dependency ("dependable") like:

{* ../../docs_src/dependencies/tutorial005_an_py310.py hl[8:9] *}