The process that happens when your API app calls the *external API* is named a "callback". Because the software that the external developer wrote sends a request to your API and then your API *calls back*, sending a request to an *external API* (that was probably created by the same developer).

                updateForm(fessConfig, form);
            });
        });
    }

    /**
     * Sends a test mail using the provided notification settings.
     *
     * @param form the mail form containing notification settings
     * @return HTML response after sending test mail
     */
    @Execute
    @Secured({ ROLE })
    public HtmlResponse sendmail(final MailForm form) {

/// info

To send data, you should use one of: `POST` (the more common), `PUT`, `DELETE` or `PATCH`.

Sending a body with a `GET` request has an undefined behavior in the specifications, nevertheless, it is supported by FastAPI, only for very complex/extreme use cases.

        "items:read items:write users:read profile openid"
    client_id: optional string. OAuth2 recommends sending the client_id and client_secret (if any)
        using HTTP Basic auth, as: client_id:client_secret
    client_secret: optional string. OAuth2 recommends sending the client_id and client_secret (if any)
        using HTTP Basic auth, as: client_id:client_secret
    """

    def __init__(

This includes, for example:

* Email notifications sent after performing an action:
    * As connecting to an email server and sending an email tends to be "slow" (several seconds), you can return the response right away and send the email notification in the background.
* Processing data:

Being able to use asynchronous functions in your tests could be useful, for example, when you're querying your database asynchronously. Imagine you want to test sending requests to your FastAPI application and then verify that your backend successfully wrote the correct data in the database, while using an async database library.

Let's look at how we can make that work.

# 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**.

* «type annotations»: «annotations de type»

* «autocomplete»: «autocomplétion»
* «autocompletion»: «autocomplétion»

* «the request» (what the client sends to the server): «la requête»
* «the response» (what the server sends back to the client): «la réponse»

* «the request body»: «le corps de la requête»
* «the response body»: «le corps de la réponse»

* «path operation»: «opération de chemin»

So, you will have to make sure your data is of the correct type. E.g. it is compatible with JSON, if you are returning a `JSONResponse`.

And also that you are not sending any data that should have been filtered by a `response_model`.

///

### More info { #more-info }

/// note | Technical Details

* «the performance»: NOT «die Performance»
* «the query»: «die Query»
* «the recap»: «die Zusammenfassung»
* «the request» (what the client sends to the server): «der Request»
* «the request body»: «der Requestbody»
* «the request bodies» (plural): «die Requestbodys»
* «the response» (what the server sends back to the client): «die Response»
* «the return type»: «der Rückgabetyp»
* «the return value»: «der Rückgabewert»