```Python hl_lines="7"
    {!> ../../../docs_src/request_forms/tutorial001.py!}
    ```

Zum Beispiel stellt eine der Möglichkeiten, die OAuth2 Spezifikation zu verwenden (genannt <abbr title='„Passwort-Fluss“'>„password flow“</abbr>), die Bedingung, einen `username` und ein `password` als Formularfelder zu senden.

    * ویژگی HTTP Digest و غیره.
* شیوه `oauth2`: تمام روش‌های OAuth2 برای مدیریت امنیت (به نام "flows").
    * چندین از این flows برای ساخت یک ارائه‌دهنده احراز هویت OAuth 2.0 مناسب هستند (مانند گوگل، فیسبوک، توییتر، گیت‌هاب و غیره):
        * ویژگی `implicit`
        * ویژگی `clientCredentials`
        * ویژگی `authorizationCode`
    * اما یک "flow" خاص وجود دارد که می‌تواند به طور کامل برای مدیریت احراز هویت در همان برنامه به کار رود:

Subclass [EventListener](https://square.github.io/okhttp/3.x/okhttp/okhttp3/EventListener.html) and override methods for the events you are interested in. In a successful HTTP call with no redirects or retries the sequence of events is described by this flow.

![Events Diagram](../assets/images/******@****.***)

 * of EventBus may be better written using <a
 * href="https://kotlinlang.org/docs/coroutines-guide.html">Kotlin coroutines</a>, including <a
 * href="https://kotlinlang.org/docs/flow.html">Flow</a> and <a
 * href="https://kotlinlang.org/docs/channels.html">Channels</a>. Yet other usages are better served
 * by individual libraries that provide specialized support for particular use cases.
 *

	// StatelessHandler is handlers for one to many requests,
	// where responses may be dropped.
	// Stateless requests provide no incoming stream and there is no flow control
	// on outgoing messages.
	StatelessHandler struct {
		Handle StatelessHandlerFn
		// OutCapacity is the output capacity on the caller.
		// If <= 0 capacity will be 1.
		OutCapacity int
	}

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## `username` und `password` entgegennehmen

Wir werden **FastAPIs** Sicherheits-Werkzeuge verwenden, um den `username` und das `password` entgegenzunehmen.

OAuth2 spezifiziert, dass der Client/Benutzer bei Verwendung des „Password Flow“ (den wir verwenden) die Felder `username` und `password` als Formulardaten senden muss.

# Simple OAuth2 with Password and Bearer

Now let's build from the previous chapter and add the missing parts to have a complete security flow.

## Get the `username` and `password`

We are going to use **FastAPI** security utilities to get the `username` and `password`.

OAuth2 specifies that when using the "password flow" (that we are using) the client/user must send a `username` and `password` fields as form data.

 * which is necessarily blocking. By implementing an {@code InputStream} it allows consumers to
 * "pull" as much data as they can handle, which is more convenient when dealing with flow
 * controlled, async APIs.
 *
 * @author Chris Nokleberg
 */
@J2ktIncompatible
@GwtIncompatible
@ElementTypesAreNonnullByDefault
final class ReaderInputStream extends InputStream {

typedef struct TF_AbstractOp TF_AbstractOp;

// Stores a function representation that can be used for execution or for
// setting functional attributes of other composite ops e.g. control flow.
typedef struct TF_AbstractFunction TF_AbstractFunction;

// This allows the client to swap the implementation of the tracing engine.
// Any future call to TF_CreateFunction will use the implementation defined
// here.