# OpenAPI Webhooks { #openapi-webhooks }

There are cases where you want to tell your API **users** that your app could call *their* app (sending a request) with some data, normally to **notify** of some type of **event**.

This means that instead of the normal process of your users sending requests to your API, it's **your API** (or your app) that could **send requests to their system** (to their API, their app).

This is normally called a **webhook**.

In this case, it would be better to get **one extra server** and run some processes on it so that they all have **enough RAM and CPU time**.

{* ../../docs_src/dependencies/tutorial008_an_py310.py hl[18:19,26:27] *}

The same way, you could have some dependencies with `yield` and some other dependencies with `return`, and have some of those depend on some of the others.

And you could have a single dependency that requires several other dependencies with `yield`, etc.

You can have any combinations of dependencies that you want.

#### The time to answer helps the attackers { #the-time-to-answer-helps-the-attackers }

At that point, by noticing that the server took some microseconds longer to send the "Incorrect username or password" response, the attackers will know that they got _something_ right, some of the initial letters were right.

    * A "token" is just a string with some content that we can use later to verify this user.
    * Normally, a token is set to expire after some time.
        * So, the user will have to log in again at some point later.
        * And if the token is stolen, the risk is less. It is not like a permanent key that will work forever (in most of the cases).

* `internal`: Internal
    * Use this for changes that only affect how the repo is managed. For example upgrades to internal dependencies, changes in GitHub Actions or scripts, etc.

/// tip

# Header

{* ../../docs_src/dependencies/tutorial013_an_py310.py ln[19:21] *}

Some text

{* ../../docs_src/bigger_applications/app_an_py310/internal/admin.py hl[3] title["app/internal/admin.py"] *}

Some more text

{* ../../docs_src/dependencies/tutorial013_an_py310.py ln[30:38] hl[31:33] *}

# Header 1 { #header-1 }

Some text

## Header 2 { #header-2 }

Some more text

### Header 3 { #header-3 }

Even more text

## Header 4 { #header-4 }

A bit more text

#Not a header

//// tab | Test

/// info
Some text
///

/// note
Some text
///

/// note | Technical details
Some text
///

/// check
Some text
///

/// tip
Some text
///

/// warning
Some text
///

/// danger
Some text
///

////

//// tab | Info

                    public String[] baz() { return new String[] {"some"}; }
                }
            """,
            v2 = """
                public class Source {
                    @$nullUnmarkedAnnotationName public String foo() { return "bar"; }
                    public @$nullUnmarkedAnnotationName String[] baz() { return new String[] {"some", null}; }
                }
            """
        ) {