## Introduction to EnterpriseAdminExtensionAbility
**EnterpriseAdminExtensionAbility** is essential to a mobile device management (MDM) application. When developing an MDM application for an enterprise, you must inherit the **EnterpriseAdminExtensionAbility** class and have the MDM service logic implemented in an **EnterpriseAdminExtensionAbility** instance. The **EnterpriseAdminExtensionAbility** class provides callbacks for the enable, disable, install, and uninstall events of a device administrator application, implementing notification of system administrator status changes.
EnterpriseAdminExtensionAbility is a mandatory component for Mobile Device Management (MDM) applications. When developing MDM applications for enterprises, you need to inherit EnterpriseAdminExtensionAbility and implement MDM service logic in the EnterpriseAdminExtensionAbility instance. EnterpriseAdminExtensionAbility implements notifications of system management status changes and defines the callbacks for when a device administrator application is enabled or disabled or an application is installed or uninstalled.
## Constraints
-***Function constraints***
-**Function constraints**
The APIs provided can be used only by device administrator applications.
EnterpriseAdminExtensionAbility is applicable only to enterprise administrator applications.
## Scenarios: Listening for the Enable, Disable, Install, and Uninstall Events of a Device Administrator Application
## Observing Activation/Deactivation of a Device Administrator Application and Installation/Removal of an Application
### Overview
**onAdminEnabled**: called when the enterprise administrator or employee deploys an MDM application and enables the DeviceAdmin permission for the application. The MDM application can set the initialization policy in the **onAdminEnabled** callback.
**onAdminEnabled**: When an enterprise administrator or employee deploys an MDM application and activates the device administrator application, this callback is invoked to notify the MDM application that the DeviceAdmin permission is activated. The initialization policy of the MDM application can set in **onAdminEnabled**.
**onAdminDisabled**: called when the system or employee disables the DeviceAdmin permission to notify the enterprise administrator that the device is no longer managed.
**onAdminDisabled**: When the device administrator application is deactivated, the callback is invoked to notify the MDM application that the DeviceAdmin permission is deactivated.
**onBundleAdded**: called to notify the enterprise administrator that the specified MDM application is installed on the device. In enterprise application administration settings, after the enterprise administrator subscribes to application installation and uninstallation events, the MDM application reports the events through the callbacks.
**onBundleAdded**: The enterprise administrator can subscribe to application installation and uninstallation events. When an application is installed on an enterprise device, the MDM application reports the event in this callback to notify the enterprise administrator.
**onBundleRemoved**: called to notify the enterprise administrator that the specified MDM application is uninstalled on the device.
**onBundleRemoved**: When an application is removed from an enterprise device, the MDM application reports the event in this callback to notify the enterprise administrator.
| EnterpriseAdminExtensionAbility | onAdminDisabled(): void | Called when the device administrator application is enabled.|
| EnterpriseAdminExtensionAbility | onBundleAdded(bundleName: string): void | Called when the MDM application is installed. |
| EnterpriseAdminExtensionAbility | onAdminEnabled(): void | Called when the device administrator application is disabled. |
| EnterpriseAdminExtensionAbility | onBundleRemoved(bundleName: string): void | Called when the MDM application is uninstalled. |
| EnterpriseAdminExtensionAbility | onAdminDisabled(): void | Called when a device administrator application is deactivated.|
| EnterpriseAdminExtensionAbility | onBundleAdded(bundleName: string): void | Called when an application is installed on a device. |
| EnterpriseAdminExtensionAbility | onAdminEnabled(): void | Called when a device administrator application is activated. |
| EnterpriseAdminExtensionAbility | onBundleRemoved(bundleName: string): void | Called when an application is removed from a device. |
### How to Develop
To implement **EnterpriseAdminExtensionAbility**, enable the device administrator application and create an **ExtensionAbility** instance from the code directory of the device administrator application. The procedure is as follows:
To implement EnterpriseAdminExtensionAbility, you need to activate the device administrator application and create **ExtensionAbility** in the code directory of the device administrator application. The procedure is as follows:
1. In the **ets** directory of the target module, right-click and choose **New > Directory** to create a directory named **EnterpriseExtAbility**.
2. Right-click the **EnterpriseExtAbility** directory and choose **New > TypeScript File** to create a file named **EnterpriseExtAbility.ts**.
3. Open the **EnterpriseExtAbility.ts** file and import the **EnterpriseAdminExtensionAbility** module. Customize a class that inherits from **EnterpriseAdminExtensionAbility** and add the required callbacks, such as **onAdminEnabled()** and **onAdminDisabled()**, through which the enterprise administrator can receive notification when the device administrator application is enabled or disabled.
2. Right-click the **EnterpriseExtAbility** directory, and choose **New > TypeScript File** to create a file named **EnterpriseExtAbility.ts**.
3. Open the **EnterpriseExtAbility.ts** file and import the **EnterpriseAdminExtensionAbility** module. Inherit the **EnterpriseAdminExtensionAbility** module to the custom class and add application notification callbacks, such as **onAdminEnabled()** and **onAdminDisabled()**. When the device administrator application is activated or deactivated, the device administrator can receive notifications.
4. Register **ServiceExtensionAbility** in the [module.json5](../quick-start/module-configuration-file.md) file of the target module. Among the parameters, set **type** to **enterpriseAdmin** and **srcEntrance** to the code path of the current ExtensionAbility.
4. Register **ServiceExtensionAbility** in the [**module.json5**](../quick-start/module-configuration-file.md) file corresponding to the project module. Set **type** to **enterpriseAdmin** and **srcEntrance** to the path of the ExtensionAbility code.
```ts
"extensionAbilities":[
...
...
@@ -78,7 +78,7 @@ To implement **EnterpriseAdminExtensionAbility**, enable the device administrato
## Example
Use the **subscribeManagedEvent** and **unsubscribeManagedEvent** APIs in the **@ohos.enterprise.adminManager** module to subscribe to and unsubscribe from the application installation and uninstallation event, respectively. After the subscription is successful, the MDM application notifies the enterprise administrator when it is installed or uninstalled on the device.
Use **subscribeManagedEvent()** and **unsubscribeManagedEvent()** in the **@ohos.enterprise.adminManager** module to subscribe to application installation and removal events. When an application is installed or removed, the MDM application is notified of the event. Then, the MDM application reports the event in the callback to notify the enterprise administrator.
