# Managing External Storage Devices (Available Only for System Applications)
# Managing External Storage Devices (for System Applications Only)
External storage devices are pluggable. OpenHarmony provides the functions of listening for the device insertion and removal events and mounting/unmounting an external storage device.
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@@ -28,13 +28,13 @@ The following table describes the broadcast related parameters.
**Table 1** Broadcast parameters
| Broadcast| Parameter|
| Broadcast| Parameter|
| -------- | -------- |
| usual.event.data.VOLUME_REMOVED | **id**: ID of the volume.<br>**diskId**: ID of the disk to which the volume belongs.|
| usual.event.data.VOLUME_UNMOUNTED | **id**: ID of the volume.<br>**diskId**: ID of the disk to which the volume belongs.<br>**volumeState**: state of the volume.|
| usual.event.data.VOLUME_MOUNTED | **id**: ID of the volume.<br>**diskId**: ID of the disk to which the volume belongs.<br>**volumeState**: state of the volume.<br>**fsUuid**: universally unique identifier (UUID) of the volume.<br>**path**: path where the volume is mounted.|
| usual.event.data.VOLUME_BAD_REMOVAL | **id**: ID of the volume.<br>**diskId**: ID of the disk to which the volume belongs.|
| usual.event.data.VOLUME_EJECT | **id**: ID of the volume.<br>**diskId**: ID of the disk to which the volume belongs.<br>**volumeState**: state of the volume.|
| usual.event.data.VOLUME_REMOVED | **id**: ID of the volume.<br>**diskId**: ID of the disk to which the volume belongs.|
| usual.event.data.VOLUME_UNMOUNTED | **id**: ID of the volume.<br>**diskId**: ID of the disk to which the volume belongs.<br>**volumeState**: state of the volume.|
| usual.event.data.VOLUME_MOUNTED | **id**: ID of the volume.<br>**diskId**: ID of the disk to which the volume belongs.<br>**volumeState**: state of the volume.<br>**fsUuid**: universally unique identifier (UUID) of the volume.<br>**path**: path where the volume is mounted.|
| usual.event.data.VOLUME_BAD_REMOVAL | **id**: ID of the volume.<br>**diskId**: ID of the disk to which the volume belongs.|
| usual.event.data.VOLUME_EJECT | **id**: ID of the volume.<br>**diskId**: ID of the disk to which the volume belongs.<br>**volumeState**: state of the volume.|
@@ -26,11 +26,7 @@ For details, see [AVSession Management](../reference/apis/js-apis-avsession.md).
| -------- | -------- |
| getAllSessionDescriptors(callback: AsyncCallback<Array<Readonly<AVSessionDescriptor>>>): void | Obtains the descriptors of all AVSessions in the system.|
| createController(sessionId: string, callback: AsyncCallback<AVSessionController>): void | Creates an AVSessionController.|
| getValidCommands(callback: AsyncCallback<Array<AVControlCommandType>>): void | Obtains valid commands supported by the AVSession.<br>Playback control commands listened by an audio and video application when it accesses the AVSession are considered as valid commands supported by the AVSession. For details, see [Provider of AVSession](using-avsession-developer.md).|
| getLaunchAbility(callback: AsyncCallback<WantAgent>): void | Obtains the UIAbility that is configured in the AVSession and can be started.<br>The UIAbility configured here is started when a user operates the UI of the controller, for example, clicking a widget in Media Controller.|
| sendAVKeyEvent(event: KeyEvent, callback: AsyncCallback<void>): void | Sends a key event to an AVSession through the AVSessionController object.|
| sendSystemAVKeyEvent(event: KeyEvent, callback: AsyncCallback<void>): void | Sends a key event to the top session.|
| sendControlCommand(command: AVControlCommand, callback: AsyncCallback<void>): void | Sends a playback control command to an AVSession through the AVSessionController object.|
| sendSystemControlCommand(command: AVControlCommand, callback: AsyncCallback<void>): void | Sends a playback control command to the top session.|
| getHistoricalSessionDescriptors(maxSize: number, callback: AsyncCallback\<Array\<Readonly\<AVSessionDescriptor>>>): void<sup>10+<sup> | Obtains the descriptors of historical sessions.|
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@@ -38,15 +34,15 @@ For details, see [AVSession Management](../reference/apis/js-apis-avsession.md).
| API| Description|
| -------- | -------- |
| getAVPlaybackState(callback: AsyncCallback<AVPlaybackState>): void | Obtains the information related to the playback state.|
| getAVMetadata(callback: AsyncCallback<AVMetadata>): void | Obtains the session metadata.|
| getOutputDevice(callback: AsyncCallback<OutputDeviceInfo>): void | Obtains the output device information.|
| sendAVKeyEvent(event: KeyEvent, callback: AsyncCallback<void>): void | Sends a key event to the session corresponding to this controller.|
| getLaunchAbility(callback: AsyncCallback<WantAgent>): void | Obtains the **WantAgent** object saved by the application in the session.|
| isActive(callback: AsyncCallback<boolean>): void | Checks whether the session is activated.|
| destroy(callback: AsyncCallback<void>): void | Destroys this controller. A controller can no longer be used after being destroyed.|
| getValidCommands(callback: AsyncCallback<Array<AVControlCommandType>>): void | Obtains valid commands supported by the session.|
| sendControlCommand(command: AVControlCommand, callback: AsyncCallback<void>): void | Sends a playback control command to the session through the controller.|
| getAVPlaybackState(callback: AsyncCallback<AVPlaybackState>): void<sup>10+<sup> | Obtains the information related to the playback state.|
| getAVMetadata(callback: AsyncCallback<AVMetadata>): void<sup>10+<sup> | Obtains the session metadata.|
| getOutputDevice(callback: AsyncCallback<OutputDeviceInfo>): void<sup>10+<sup> | Obtains the output device information.|
| sendAVKeyEvent(event: KeyEvent, callback: AsyncCallback<void>): void<sup>10+<sup> | Sends a key event to the session corresponding to this controller.|
| getLaunchAbility(callback: AsyncCallback<WantAgent>): void<sup>10+<sup> | Obtains the **WantAgent** object saved by the application in the session.|
| isActive(callback: AsyncCallback<boolean>): void<sup>10+<sup> | Checks whether the session is activated.|
| destroy(callback: AsyncCallback<void>): void<sup>10+<sup> | Destroys this controller. A controller can no longer be used after being destroyed.|
| getValidCommands(callback: AsyncCallback<Array<AVControlCommandType>>): void<sup>10+<sup> | Obtains valid commands supported by the session.|
| sendControlCommand(command: AVControlCommand, callback: AsyncCallback<void>): void<sup>10+<sup> | Sends a playback control command to the session through the controller.|
| sendCommonCommand(command: string, args: {[key: string]: Object}, callback: AsyncCallback<void>): void<sup>10+<sup> | Sends a custom playback control command to the session through the controller.|
| getAVQueueItems(callback: AsyncCallback<Array<AVQueueItem>>): void<sup>10+<sup> | Obtains the information related to the items in the playlist.|
| getAVQueueTitle(callback: AsyncCallback<string>): void<sup>10+<sup> | Obtains the name of the playlist.|
@@ -16,15 +16,15 @@ For details, see [AVSession Management](../reference/apis/js-apis-avsession.md).
| API| Description|
| -------- | -------- |
| createAVSession(context: Context, tag: string, type: AVSessionType, callback: AsyncCallback<AVSession>): void | Creates an AVSession.<br>Only one AVSession can be created for a UIAbility.|
| setLaunchAbility(ability: WantAgent, callback: AsyncCallback<void>): void | Starts a UIAbility.|
| getController(callback: AsyncCallback<AVSessionController>): void | Obtains the controller of the AVSession.|
| getOutputDevice(callback: AsyncCallback<OutputDeviceInfo>): void | Obtains the output device information.|
| activate(callback: AsyncCallback<void>): void | Activates the AVSession.|
| deactivate(callback: AsyncCallback<void>): void | Deactivates this session.|
| destroy(callback: AsyncCallback<void>): void | Destroys the AVSession.|
| createAVSession(context: Context, tag: string, type: AVSessionType, callback: AsyncCallback<AVSession>): void<sup>10+<sup> | Creates an AVSession.<br>Only one AVSession can be created for a UIAbility.|
# Common Events of the Resource Scheduling Subsystem
This document lists the common system events provided by the resource scheduling subsystem to applications. Applications can use [APIs](../js-apis-commonEventManager.md) to subscribe to common system events.
# Common Events of the Resource Scheduler Subsystem
This document lists the common system events provided by the resource scheduler subsystem to applications. Applications can use [APIs](../js-apis-commonEventManager.md) to subscribe to common system events.
