# DataShareExtensionAbility (for System Applications Only)
DataShareExtensionAbility provides the data sharing capability. System applications can implement a DataShareExtensionAbility or access an existing DataShareExtensionAbility in the system. Third-party applications can only access an existing DataShareExtensionAbility. For details, see [Cross-Application Data Sharing Overview](../database/share-device-data-across-apps-overview.md).
One UIAbility instance corresponds to one mission. The number of UIAbility instances is related to the UIAbility launch type, specified by **launchType**, which is configured in the **config.json** file in the FA model and the [module.json5](../quick-start/module-configuration-file.md) file in the stage model.
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@@ -11,13 +11,13 @@ The following describes how the mission list manager manages the UIAbility insta
-**multiton**: Each time [startAbility()](../reference/apis/js-apis-inner-application-uiAbilityContext.md#uiabilitycontextstartability) is called, a **UIAbility** instance is created in the application process.
-**multiton**: Each time [startAbility()](../reference/apis/js-apis-inner-application-uiAbilityContext.md#uiabilitycontextstartability) is called, a UIAbility instance is created in the application process.
-**specified**: The ([onAcceptWant()](../reference/apis/js-apis-app-ability-abilityStage.md#abilitystageonacceptwant)) method of [AbilityStage](abilitystage.md) determines whether to create an instance.
-**specified**: The ([onAcceptWant()](../reference/apis/js-apis-app-ability-abilityStage.md#abilitystageonacceptwant)) method of [AbilityStage](abilitystage.md) determines whether to create a UIAbility instance.
Before getting started with the development of mission management, be familiar with the following concepts related to mission management:
- AbilityRecord: minimum unit for the system service to manage a UIAbility instance. It corresponds to a UIAbility component instance of an application.
- AbilityRecord: minimum unit for the system service to manage a UIAbility instance. It corresponds to a UIAbility component instance of an application. A maximum of 512 UIAbility instances can be managed on the system service side.
- MissionRecord: minimum unit for mission management. One MissionRecord has only one AbilityRecord. In other words, a UIAbility component instance corresponds to a mission.
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@@ -30,9 +30,9 @@ Missions are managed by system applications (such as home screen), rather than t
A UIAbility instance corresponds to an independent mission. Therefore, when an application calls [startAbility()](../reference/apis/js-apis-inner-application-uiAbilityContext.md#uiabilitycontextstartability) to start a UIAbility, a mission is created.
To call [missionManager](../reference/apis/js-apis-application-missionManager.md) to manage missions, the home screen application must request the **ohos.permission.MANAGE_MISSIONS** permission. For details about the configuration, see [Declaring Permissions in the Configuration File](../security/accesstoken-guidelines.md#declaring-permissions-in-the-configuration-file).
1.To call [missionManager](../reference/apis/js-apis-application-missionManager.md) to manage missions, the home screen application must request the **ohos.permission.MANAGE_MISSIONS** permission. For details about the configuration, see [Declaring Permissions in the Configuration File](../security/accesstoken-guidelines.md#declaring-permissions-in-the-configuration-file).
You can use **missionManager** to manage missions, for example, listening for mission changes, obtaining mission information or snapshots, and clearing, locking, or unlocking missions.
2.You can use **missionManager** to manage missions, for example, listening for mission changes, obtaining mission information or snapshots, and clearing, locking, or unlocking missions.
Based on the OpenHarmony thread model, different services run on different threads. Service interaction requires inter-thread communication. Threads can communicate with each other in Emitter or Worker mode. Emitter is mainly used for event synchronization between threads, and Worker is mainly used to execute time-consuming tasks.
> **NOTE**
>
> The FA model provides an independent thread for each ability. Emitter is mainly used for event synchronization within the ability thread, between a pair of ability threads, or between the ability thread and worker thread.
