@Singleton
public class DefaultClassRealmManager implements ClassRealmManager {
    public static final String API_REALMID = "maven.api";

    public static final String API_V4_REALMID = "maven.api.v4";

    /**
     * During normal command line build, ClassWorld is loaded by jvm system classloader, which only includes
     * plexus-classworlds jar and possibly javaagent classes, see https://issues.apache.org/jira/browse/MNG-4747.
     * <p>

Puedes definir manejadores de eventos (funciones) que necesitan ser ejecutadas antes de que la aplicación se inicie, o cuando la aplicación se está cerrando.

Estas funciones pueden ser declaradas con `async def` o `def` normal.

### Evento `startup` { #startup-event }

Para añadir una función que debería ejecutarse antes de que la aplicación inicie, declárala con el evento `"startup"`:

        suggester.createIndexIfNothing();
        suggester.createIndexIfNothing();

        // Should still be able to use the index
        suggester.refresh();
        assertEquals("Index should work normally", 0, suggester.getAllWordsNum());
    }

    // ============================================================
    // Tests for data persistence and index lifecycle

API 的用户（外部开发者）要在您的 API 内使用 POST 请求创建一条发票记录。

（假设）您的 API 将：

* 把发票发送至外部开发者的消费者
* 归集现金
* 把通知发送至 API 的用户（外部开发者）
    * 通过（从您的 API）发送 POST 请求至外部 API（即**回调**）来完成

## 常规 **FastAPI** 应用 { #the-normal-fastapi-app }

添加回调前，首先看下常规 API 应用是什么样子。

常规 API 应用包含接收 `Invoice` 请求体的*路径操作*，还有包含回调 URL 的查询参数 `callback_url`。

这部分代码很常规，您对绝大多数代码应该都比较熟悉了：

{* ../../docs_src/openapi_callbacks/tutorial001_py310.py hl[7:11,34:51] *}

Dies wurde in Version 0.110.0 geändert, um unbehandelten Speicherverbrauch durch weitergeleitete Exceptions ohne Handler (interne Serverfehler) zu beheben und um es mit dem Verhalten von normalem Python-Code konsistent zu machen.

### Hintergrundtasks und Abhängigkeiten mit `yield`, Technische Details { #background-tasks-and-dependencies-with-yield-technical-details }

Sie können `async def` oder einfach `def` verwenden.

Und Sie können Abhängigkeiten mit `async def` innerhalb normaler `def`-*Pfadoperation-Funktionen* oder `def`-Abhängigkeiten innerhalb von `async def`-*Pfadoperation-Funktionen*, usw. deklarieren.

Es spielt keine Rolle. **FastAPI** weiß, was zu tun ist.

/// note | Hinweis

{* ../../docs_src/handling_errors/tutorial001_py310.py hl[1] *}

### Lanza un `HTTPException` en tu código { #raise-an-httpexception-in-your-code }

`HTTPException` es una excepción de Python normal con datos adicionales relevantes para APIs.

Debido a que es una excepción de Python, no la `return`, sino que la `raise`.

{* ../../docs_src/custom_response/tutorial006c_py310.py hl[2,7,9] *}

### `StreamingResponse` { #streamingresponse }

Bir async generator veya normal generator/iterator (içinde `yield` olan bir fonksiyon) alır ve response body’yi stream eder.

{* ../../docs_src/custom_response/tutorial007_py310.py hl[3,16] *}

/// note | Teknik Detaylar

    //                                                                           Attribute
    //                                                                           =========
    // keeping parsed request parameters, normal texts or uploaded files
    // keys are requested parameter names (treated as field name here)
    protected Map<String, Object> elementsAll; // lazy-loaded, then after not null

     */
    int ATTR_ARCHIVE = 0x20;

    // extended file attribute encoding(others same as above)
    /**
     * File is compressed.
     */
    int ATTR_COMPRESSED = 0x800;
    /**
     * File is a normal file.
     */
    int ATTR_NORMAL = 0x080;
    /**
     * File is temporary.
     */
    int ATTR_TEMPORARY = 0x100;

    // access mask encoding
    /**