# ServiceExtensionContext (System API)

The ServiceExtensionContext module, inherited from **ExtensionContext**, provides context for the ServiceExtensionAbility.

You can use the APIs of this module to start, terminate, connect, and disconnect an ability.

> **NOTE**
> 
>  - The initial APIs of this module are supported since API version 9. Newly added APIs will be marked with a superscript to indicate their earliest API version.
>  - The APIs of this module can be used only in the stage model.
>  - The APIs of this module must be used in the main thread, but not in sub-threads such as Worker and TaskPool.
>  - The APIs provided by this module are system APIs.

## Modules to Import

```ts
import { common } from '@kit.AbilityKit';
```

## Usage

Before using the **ServiceExtensionContext** module, you must define a child class that inherits from **ServiceExtensionAbility**.

**Example**

```ts
import { ServiceExtensionAbility } from '@kit.AbilityKit';
import { rpc } from '@kit.IPCKit';

let commRemote: rpc.IRemoteObject | null; // Release the instance when the connection is disconnected.

class EntryAbility extends ServiceExtensionAbility {
  onCreate() {
    let context = this.context; // Obtain a ServiceExtensionContext instance.
  }
}
```

## ServiceExtensionContext.startAbility

startAbility(want: Want, callback: AsyncCallback<void>): void;

Starts an ability. This API uses an asynchronous callback to return the result. It can be called only by the main thread.

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**System API**: This is a system API and cannot be called by third-party applications.

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| want | [Want](js-apis-app-ability-want.md)  | Yes| Want information about the target ability, such as the ability name and bundle name.|
| callback | AsyncCallback<void> | Yes| Callback used to return the result.|

**Error codes**

For details about the error codes, see [Universal Error Codes](../errorcode-universal.md) and [Ability Error Codes](errorcode-ability.md).

| ID| Error Message|
| ------- | -------- |
| 201 | The application does not have permission to call the interface. |
| 401 | Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed. |
| 16000001 | The specified ability does not exist. |
| 16000002 | Incorrect ability type. |
| 16000004 | Failed to start the invisible ability. |
| 16000005 | The specified process does not have the permission. |
| 16000006 | Cross-user operations are not allowed. |
| 16000008 | The crowdtesting application expires. |
| 16000009 | An ability cannot be started or stopped in Wukong mode. |
| 16000010 | The call with the continuation flag is forbidden.        |
| 16000011 | The context does not exist.        |
| 16000012 | The application is controlled.        |
| 16000013 | The application is controlled by EDM.       |
| 16000019 | No matching ability is found. |
| 16000050 | Internal error. |
| 16000053 | The ability is not on the top of the UI. |
| 16000055 | Installation-free timed out. |
| 16000071 | App clone is not supported. |
| 16000072 | App clone or multi-instance is not supported. |
| 16000073 | The app clone index is invalid. |
| 16000076 | The app instance key is invalid. |
| 16000077 | The number of app instances reaches the limit. |
| 16000078 | The multi-instance is not supported. |
| 16000079 | The APP_INSTANCE_KEY cannot be specified. |
| 16000080 | Creating an instance is not supported. |
| 16000082 | The UIAbility is being started. |
| 16200001 | The caller has been released. |

**Example**

```ts
import { ServiceExtensionAbility, Want } from '@kit.AbilityKit';
import { BusinessError } from '@kit.BasicServicesKit';

class EntryAbility extends ServiceExtensionAbility {
  onCreate() {
    let want: Want = {
      bundleName: 'com.example.myapp',
      abilityName: 'MyAbility'
    };

    try {
      this.context.startAbility(want, (error: BusinessError) => {
        if (error.code) {
          // Process service logic errors.
          console.error(`startAbility failed, error.code: ${error.code}, error.message: ${error.message}`);
          return;
        }
        // Carry out normal service processing.
        console.log('startAbility succeed');
      });
    } catch (paramError) {
      // Process input parameter errors.
      console.error(`error.code: ${paramError.code}, error.message: ${paramError.message}`);
    }
  }
}
```

## ServiceExtensionContext.startAbility

startAbility(want: Want, options?: StartOptions): Promise\<void>;

Starts an ability. This API uses a promise to return the result. It can be called only by the main thread.

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**System API**: This is a system API and cannot be called by third-party applications.

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| want | [Want](js-apis-app-ability-want.md)  | Yes| Want information about the target ability, such as the ability name and bundle name.|
| options | [StartOptions](js-apis-app-ability-startOptions.md) | No| Parameters used for starting the ability.|

**Return value**

| Type| Description|
| -------- | -------- |
| Promise&lt;void&gt; | Promise used to return the result.|

**Error codes**

For details about the error codes, see [Universal Error Codes](../errorcode-universal.md) and [Ability Error Codes](errorcode-ability.md).

| ID| Error Message|
| ------- | -------- |
| 201 | The application does not have permission to call the interface. |
| 401 | Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed. |
| 16000001 | The specified ability does not exist. |
| 16000002 | Incorrect ability type. |
| 16000004 | Failed to start the invisible ability. |
| 16000005 | The specified process does not have the permission. |
| 16000006 | Cross-user operations are not allowed. |
| 16000008 | The crowdtesting application expires. |
| 16000009 | An ability cannot be started or stopped in Wukong mode. |
| 16000010 | The call with the continuation flag is forbidden.        |
| 16000011 | The context does not exist.        |
| 16000012 | The application is controlled.        |
| 16000013 | The application is controlled by EDM.       |
| 16000019 | No matching ability is found. |
| 16000050 | Internal error. |
| 16000053 | The ability is not on the top of the UI. |
| 16000055 | Installation-free timed out. |
| 16000071 | App clone is not supported. |
| 16000072 | App clone or multi-instance is not supported. |
| 16000073 | The app clone index is invalid. |
| 16000076 | The app instance key is invalid. |
| 16000077 | The number of app instances reaches the limit. |
| 16000078 | The multi-instance is not supported. |
| 16000079 | The APP_INSTANCE_KEY cannot be specified. |
| 16000080 | Creating an instance is not supported. |
| 16000082 | The UIAbility is being started. |
| 16200001 | The caller has been released. |

**Example**

```ts
import { ServiceExtensionAbility, Want, StartOptions } from '@kit.AbilityKit';
import { BusinessError } from '@kit.BasicServicesKit';

class EntryAbility extends ServiceExtensionAbility {
  onCreate() {
    let want: Want = {
      bundleName: 'com.example.myapp',
      abilityName: 'MyAbility'
    };
    let options: StartOptions = {
      windowMode: 0,
    };

    try {
      this.context.startAbility(want, options)
        .then((data: void) => {
          // Carry out normal service processing.
          console.log('startAbility succeed');
        })
        .catch((error: BusinessError) => {
          // Process service logic errors.
          console.error(`startAbility failed, error.code: ${error.code}, error.message: ${error.message}`);
        });
    } catch (paramError) {
      // Process input parameter errors.
      console.error(`error.code: ${paramError.code}, error.message: ${paramError.message}`);
    }
  }
}
```

## ServiceExtensionContext.startAbility

startAbility(want: Want, options: StartOptions, callback: AsyncCallback&lt;void&gt;): void

Starts an ability with the start options specified. This API uses an asynchronous callback to return the result. It can be called only by the main thread.

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**System API**: This is a system API and cannot be called by third-party applications.

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| want | [Want](js-apis-app-ability-want.md)  | Yes| Want information about the target ability.|
| options | [StartOptions](js-apis-app-ability-startOptions.md) | Yes| Parameters used for starting the ability.|
| callback | AsyncCallback&lt;void&gt; | Yes| Callback used to return the result.|

**Error codes**

For details about the error codes, see [Universal Error Codes](../errorcode-universal.md) and [Ability Error Codes](errorcode-ability.md).

| ID| Error Message|
| ------- | -------- |
| 201 | The application does not have permission to call the interface. |
| 401 | Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed. |
| 16000001 | The specified ability does not exist. |
| 16000002 | Incorrect ability type. |
| 16000004 | Failed to start the invisible ability. |
| 16000005 | The specified process does not have the permission. |
| 16000006 | Cross-user operations are not allowed. |
| 16000008 | The crowdtesting application expires. |
| 16000009 | An ability cannot be started or stopped in Wukong mode. |
| 16000010 | The call with the continuation flag is forbidden.        |
| 16000011 | The context does not exist.        |
| 16000012 | The application is controlled.        |
| 16000013 | The application is controlled by EDM.       |
| 16000019 | No matching ability is found. |
| 16000050 | Internal error. |
| 16000053 | The ability is not on the top of the UI. |
| 16000055 | Installation-free timed out. |
| 16000071 | App clone is not supported. |
| 16000072 | App clone or multi-instance is not supported. |
| 16000073 | The app clone index is invalid. |
| 16000076 | The app instance key is invalid. |
| 16000077 | The number of app instances reaches the limit. |
| 16000078 | The multi-instance is not supported. |
| 16000079 | The APP_INSTANCE_KEY cannot be specified. |
| 16000080 | Creating an instance is not supported. |
| 16000082 | The UIAbility is being started. |
| 16200001 | The caller has been released. |

**Example**

```ts
import { ServiceExtensionAbility, Want, StartOptions } from '@kit.AbilityKit';
import { BusinessError } from '@kit.BasicServicesKit';

class EntryAbility extends ServiceExtensionAbility {
  onCreate() {
    let want: Want = {
      deviceId: '',
      bundleName: 'com.example.myapplication',
      abilityName: 'EntryAbility'
    };
    let options: StartOptions = {
      windowMode: 0
    };

    try {
      this.context.startAbility(want, options, (error: BusinessError) => {
        if (error.code) {
          // Process service logic errors.
          console.error(`startAbility failed, error.code: ${error.code}, error.message: ${error.message}`);
          return;
        }
        // Carry out normal service processing.
        console.log('startAbility succeed');
      });
    } catch (paramError) {
      // Process input parameter errors.
      console.error(`error.code: ${paramError.code}, error.message: ${paramError.message}`);
    }
  }
}
```

## ServiceExtensionContext.startAbilityWithAccount

startAbilityWithAccount(want: Want, accountId: number, callback: AsyncCallback\<void>): void;

Starts an ability with the account ID specified. This API uses an asynchronous callback to return the result. It can be called only by the main thread.

> **NOTE**
>
> For details about the startup rules for the components in the stage model, see [Component Startup Rules (Stage Model)](../../application-models/component-startup-rules.md).

**Required permissions**: ohos.permission.INTERACT_ACROSS_LOCAL_ACCOUNTS

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**System API**: This is a system API and cannot be called by third-party applications.

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| want | [Want](js-apis-app-ability-want.md) | Yes| Want information about the target ability.|
| accountId | number | Yes| ID of a system account. For details, see [getCreatedOsAccountsCount](../apis-basic-services-kit/js-apis-osAccount.md#getcreatedosaccountscountdeprecated).|
| callback | AsyncCallback\<void\> | Yes| Callback used to return the result.|

**Error codes**

For details about the error codes, see [Universal Error Codes](../errorcode-universal.md) and [Ability Error Codes](errorcode-ability.md).

| ID| Error Message|
| ------- | -------- |
| 201 | The application does not have permission to call the interface. |
| 202 | The application is not system-app, can not use system-api. |
| 401 | Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed. |
| 16000001 | The specified ability does not exist. |
| 16000002 | Incorrect ability type. |
| 16000004 | Failed to start the invisible ability. |
| 16000005 | The specified process does not have the permission. |
| 16000006 | Cross-user operations are not allowed. |
| 16000008 | The crowdtesting application expires. |
| 16000009 | An ability cannot be started or stopped in Wukong mode. |
| 16000010 | The call with the continuation flag is forbidden.        |
| 16000011 | The context does not exist.        |
| 16000012 | The application is controlled.        |
| 16000013 | The application is controlled by EDM.       |
| 16000019 | No matching ability is found. |
| 16000050 | Internal error. |
| 16000053 | The ability is not on the top of the UI. |
| 16000055 | Installation-free timed out. |
| 16000071 | App clone is not supported. |
| 16000072 | App clone or multi-instance is not supported. |
| 16000073 | The app clone index is invalid. |
| 16000076 | The app instance key is invalid. |
| 16000077 | The number of app instances reaches the limit. |
| 16000078 | The multi-instance is not supported. |
| 16000079 | The APP_INSTANCE_KEY cannot be specified. |
| 16000080 | Creating an instance is not supported. |
| 16000082 | The UIAbility is being started. |
| 16200001 | The caller has been released. |

**Example**

```ts
import { ServiceExtensionAbility, Want, StartOptions } from '@kit.AbilityKit';
import { BusinessError } from '@kit.BasicServicesKit';

class EntryAbility extends ServiceExtensionAbility {
  onCreate() {
    let want: Want = {
      deviceId: '',
      bundleName: 'com.example.myapplication',
      abilityName: 'EntryAbility'
    };
    let accountId = 100;

    try {
      this.context.startAbilityWithAccount(want, accountId, (error: BusinessError) => {
        if (error.code) {
          // Process service logic errors.
          console.error(`startAbilityWithAccount failed, error.code: ${error.code}, error.message: ${error.message}`);
          return;
        }
        // Carry out normal service processing.
        console.log('startAbilityWithAccount succeed');
      });
    } catch (paramError) {
      // Process input parameter errors.
      console.error(`error.code: ${paramError.code}, error.message: ${paramError.message}`);
    }
  }
}
```

## ServiceExtensionContext.startAbilityWithAccount

startAbilityWithAccount(want: Want, accountId: number, options: StartOptions, callback: AsyncCallback\<void\>): void;

Starts an ability with the account ID and start options specified. This API uses an asynchronous callback to return the result. It can be called only by the main thread.

> **NOTE**
>
> For details about the startup rules for the components in the stage model, see [Component Startup Rules (Stage Model)](../../application-models/component-startup-rules.md).

**Required permissions**: ohos.permission.INTERACT_ACROSS_LOCAL_ACCOUNTS

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**System API**: This is a system API and cannot be called by third-party applications.

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| want | [Want](js-apis-app-ability-want.md) | Yes| Want information about the target ability.|
| accountId | number | Yes| ID of a system account. For details, see [getCreatedOsAccountsCount](../apis-basic-services-kit/js-apis-osAccount.md#getcreatedosaccountscountdeprecated).|
| options | [StartOptions](js-apis-app-ability-startOptions.md) | Yes| Parameters used for starting the ability.|
| callback | AsyncCallback\<void\> | Yes| Callback used to return the result.|

**Error codes**

For details about the error codes, see [Universal Error Codes](../errorcode-universal.md) and [Ability Error Codes](errorcode-ability.md).

| ID| Error Message|
| ------- | -------- |
| 201 | The application does not have permission to call the interface. |
| 202 | The application is not system-app, can not use system-api. |
| 401 | Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed. |
| 16000001 | The specified ability does not exist. |
| 16000002 | Incorrect ability type. |
| 16000004 | Failed to start the invisible ability. |
| 16000005 | The specified process does not have the permission. |
| 16000006 | Cross-user operations are not allowed. |
| 16000008 | The crowdtesting application expires. |
| 16000009 | An ability cannot be started or stopped in Wukong mode. |
| 16000010 | The call with the continuation flag is forbidden.        |
| 16000011 | The context does not exist.        |
| 16000012 | The application is controlled.        |
| 16000013 | The application is controlled by EDM.       |
| 16000019 | No matching ability is found. |
| 16000050 | Internal error. |
| 16000053 | The ability is not on the top of the UI. |
| 16000055 | Installation-free timed out. |
| 16000071 | App clone is not supported. |
| 16000072 | App clone or multi-instance is not supported. |
| 16000073 | The app clone index is invalid. |
| 16000076 | The app instance key is invalid. |
| 16000077 | The number of app instances reaches the limit. |
| 16000078 | The multi-instance is not supported. |
| 16000079 | The APP_INSTANCE_KEY cannot be specified. |
| 16000080 | Creating an instance is not supported. |
| 16000082 | The UIAbility is being started. |
| 16200001 | The caller has been released. |

**Example**

```ts
import { ServiceExtensionAbility, Want, StartOptions } from '@kit.AbilityKit';
import { BusinessError } from '@kit.BasicServicesKit';

class EntryAbility extends ServiceExtensionAbility {
  onCreate() {
    let want: Want = {
      deviceId: '',
      bundleName: 'com.example.myapplication',
      abilityName: 'EntryAbility'
    };
    let accountId = 100;
    let options: StartOptions = {
      windowMode: 0
    };

    try {
      this.context.startAbilityWithAccount(want, accountId, options, (error: BusinessError) => {
        if (error.code) {
          // Process service logic errors.
          console.error(`startAbilityWithAccount failed, error.code: ${error.code}, error.message: ${error.message}`);
          return;
        }
        // Carry out normal service processing.
        console.log('startAbilityWithAccount succeed');
      });
    } catch (paramError) {
      // Process input parameter errors.
      console.error(`error.code: ${(paramError as BusinessError).code}, error.message: ${(paramError as BusinessError).message}`);
    }
  }
}
```


## ServiceExtensionContext.startAbilityWithAccount

startAbilityWithAccount(want: Want, accountId: number, options?: StartOptions): Promise\<void>;

Starts an ability with the account ID specified. This API uses a promise to return the result. It can be called only by the main thread.

> **NOTE**
>
> For details about the startup rules for the components in the stage model, see [Component Startup Rules (Stage Model)](../../application-models/component-startup-rules.md).

**Required permissions**: ohos.permission.INTERACT_ACROSS_LOCAL_ACCOUNTS

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**System API**: This is a system API and cannot be called by third-party applications.

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| want | [Want](js-apis-app-ability-want.md) | Yes| Want information about the target ability.|
| accountId | number | Yes| ID of a system account. For details, see [getCreatedOsAccountsCount](../apis-basic-services-kit/js-apis-osAccount.md#getcreatedosaccountscountdeprecated-1).|
| options | [StartOptions](js-apis-app-ability-startOptions.md) | No| Parameters used for starting the ability.|

**Return value**

| Type| Description|
| -------- | -------- |
| Promise&lt;void&gt; | Promise used to return the result.|

**Error codes**

For details about the error codes, see [Universal Error Codes](../errorcode-universal.md) and [Ability Error Codes](errorcode-ability.md).

| ID| Error Message|
| ------- | -------- |
| 201 | The application does not have permission to call the interface. |
| 202 | The application is not system-app, can not use system-api. |
| 401 | Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed. |
| 16000001 | The specified ability does not exist. |
| 16000002 | Incorrect ability type. |
| 16000004 | Failed to start the invisible ability. |
| 16000005 | The specified process does not have the permission. |
| 16000006 | Cross-user operations are not allowed. |
| 16000008 | The crowdtesting application expires. |
| 16000009 | An ability cannot be started or stopped in Wukong mode. |
| 16000010 | The call with the continuation flag is forbidden.        |
| 16000011 | The context does not exist.        |
| 16000012 | The application is controlled.        |
| 16000013 | The application is controlled by EDM.       |
| 16000019 | No matching ability is found. |
| 16000050 | Internal error. |
| 16000053 | The ability is not on the top of the UI. |
| 16000055 | Installation-free timed out. |
| 16000071 | App clone is not supported. |
| 16000072 | App clone or multi-instance is not supported. |
| 16000073 | The app clone index is invalid. |
| 16000076 | The app instance key is invalid. |
| 16000077 | The number of app instances reaches the limit. |
| 16000078 | The multi-instance is not supported. |
| 16000079 | The APP_INSTANCE_KEY cannot be specified. |
| 16000080 | Creating an instance is not supported. |
| 16000082 | The UIAbility is being started. |
| 16200001 | The caller has been released. |

**Example**

```ts
import { ServiceExtensionAbility, Want, StartOptions } from '@kit.AbilityKit';
import { BusinessError } from '@kit.BasicServicesKit';

class EntryAbility extends ServiceExtensionAbility {
  onCreate() {
    let want: Want = {
      deviceId: '',
      bundleName: 'com.example.myapplication',
      abilityName: 'EntryAbility'
    };
    let accountId = 100;
    let options: StartOptions = {
      windowMode: 0
    };

    try {
      this.context.startAbilityWithAccount(want, accountId, options)
        .then((data: void) => {
          // Carry out normal service processing.
          console.log('startAbilityWithAccount succeed');
        })
        .catch((error: BusinessError) => {
          // Process service logic errors.
          console.error(`startAbilityWithAccount failed, error.code: ${error.code}, error.message: ${error.message}`);
        });
    } catch (paramError) {
      // Process input parameter errors.
      console.error(`error.code: ${(paramError as BusinessError).code}, error.message: ${(paramError as BusinessError).message}`);
    }
  }
}
```

## ServiceExtensionContext.startServiceExtensionAbility

startServiceExtensionAbility(want: Want, callback: AsyncCallback\<void>): void;

Starts a new ServiceExtensionAbility. This API uses an asynchronous callback to return the result.

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**System API**: This is a system API and cannot be called by third-party applications.

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| want | [Want](js-apis-app-ability-want.md) | Yes| Want information about the target ability.|
| callback | AsyncCallback\<void\> | Yes| Callback used to return the result.|

**Error codes**

For details about the error codes, see [Universal Error Codes](../errorcode-universal.md) and [Ability Error Codes](errorcode-ability.md).

| ID| Error Message|
| ------- | -------- |
| 201 | The application does not have permission to call the interface. |
| 202 | The application is not system-app, can not use system-api. |
| 401 | Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed. |
| 16000001 | The specified ability does not exist. |
| 16000002 | Incorrect ability type. |
| 16000004 | Failed to start the invisible ability. |
| 16000005 | The specified process does not have the permission. |
| 16000006 | Cross-user operations are not allowed. |
| 16000008 | The crowdtesting application expires. |
| 16000011 | The context does not exist.        |
| 16000012 | The application is controlled.        |
| 16000013 | The application is controlled by EDM.       |
| 16000019 | No matching ability is found. |
| 16000050 | Internal error. |
| 16200001 | The caller has been released. |

**Example**

```ts
import { ServiceExtensionAbility, Want } from '@kit.AbilityKit';
import { BusinessError } from '@kit.BasicServicesKit';

class EntryAbility extends ServiceExtensionAbility {
  onCreate() {
    let want: Want = {
      deviceId: '',
      bundleName: 'com.example.myapplication',
      abilityName: 'EntryAbility'
    };

    try {
      this.context.startServiceExtensionAbility(want, (error: BusinessError) => {
        if (error.code) {
          // Process service logic errors.
          console.error(`startServiceExtensionAbility failed, error.code: ${error.code}, error.message: ${error.message}`);
          return;
        }
        // Carry out normal service processing.
        console.log('startServiceExtensionAbility succeed');
      });
    } catch (paramError) {
      // Process input parameter errors.
      console.error(`error.code: ${(paramError as BusinessError).code}, error.message: ${(paramError as BusinessError).message}`);
    }
  }
}
```

## ServiceExtensionContext.startServiceExtensionAbility

startServiceExtensionAbility(want: Want): Promise\<void>;

Starts a new ServiceExtensionAbility. This API uses a promise to return the result.

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**System API**: This is a system API and cannot be called by third-party applications.

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| want | [Want](js-apis-app-ability-want.md) | Yes| Want information about the target ability.|

**Return value**

| Type| Description|
| -------- | -------- |
| Promise&lt;void&gt; | Promise used to return the result.|

**Error codes**

For details about the error codes, see [Universal Error Codes](../errorcode-universal.md) and [Ability Error Codes](errorcode-ability.md).

| ID| Error Message|
| ------- | -------- |
| 201 | The application does not have permission to call the interface. |
| 202 | The application is not system-app, can not use system-api. |
| 401 | Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed. |
| 16000001 | The specified ability does not exist. |
| 16000002 | Incorrect ability type. |
| 16000004 | Failed to start the invisible ability. |
| 16000005 | The specified process does not have the permission. |
| 16000006 | Cross-user operations are not allowed. |
| 16000008 | The crowdtesting application expires. |
| 16000011 | The context does not exist.        |
| 16000012 | The application is controlled.        |
| 16000013 | The application is controlled by EDM.       |
| 16000019 | No matching ability is found. |
| 16000050 | Internal error. |
| 16200001 | The caller has been released. |

**Example**

```ts
import { ServiceExtensionAbility, Want } from '@kit.AbilityKit';
import { BusinessError } from '@kit.BasicServicesKit';

class EntryAbility extends ServiceExtensionAbility {
  onCreate() {
    let want: Want = {
      deviceId: '',
      bundleName: 'com.example.myapplication',
      abilityName: 'EntryAbility'
    };

    try {
      this.context.startServiceExtensionAbility(want)
        .then((data) => {
          // Carry out normal service processing.
          console.log('startServiceExtensionAbility succeed');
        })
        .catch((error: BusinessError) => {
          // Process service logic errors.
          console.error(`startServiceExtensionAbility failed, error.code: ${error.code}, error.message: ${error.message}`);
        });
    } catch (paramError) {
      // Process input parameter errors.
      console.error(`error.code: ${(paramError as BusinessError).code}, error.message: ${(paramError as BusinessError).message}`);
    }
  }
}
```

## ServiceExtensionContext.startServiceExtensionAbilityWithAccount

startServiceExtensionAbilityWithAccount(want: Want, accountId: number, callback: AsyncCallback\<void>): void;

Starts a new ServiceExtensionAbility with the account ID specified. This API uses an asynchronous callback to return the result.

> **NOTE**
> 
> For details about the startup rules for the components in the stage model, see [Component Startup Rules (Stage Model)](../../application-models/component-startup-rules.md). 
> Permission verification is not required when **accountId** specifies the current user.

**Required permissions**: ohos.permission.INTERACT_ACROSS_LOCAL_ACCOUNTS

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**System API**: This is a system API and cannot be called by third-party applications.

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| want | [Want](js-apis-app-ability-want.md) | Yes| Want information about the target ability.|
| accountId | number | Yes| ID of a system account. For details, see [getCreatedOsAccountsCount](../apis-basic-services-kit/js-apis-osAccount.md#getcreatedosaccountscountdeprecated).|
| callback | AsyncCallback\<void\> | Yes| Callback used to return the result.|

**Error codes**

For details about the error codes, see [Universal Error Codes](../errorcode-universal.md) and [Ability Error Codes](errorcode-ability.md).

| ID| Error Message|
| ------- | -------- |
| 201 | The application does not have permission to call the interface. |
| 202 | The application is not system-app, can not use system-api. |
| 401 | Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed. |
| 16000001 | The specified ability does not exist. |
| 16000002 | Incorrect ability type. |
| 16000004 | Failed to start the invisible ability. |
| 16000005 | The specified process does not have the permission. |
| 16000006 | Cross-user operations are not allowed. |
| 16000008 | The crowdtesting application expires. |
| 16000011 | The context does not exist.        |
| 16000012 | The application is controlled.        |
| 16000013 | The application is controlled by EDM.       |
| 16000019 | No matching ability is found. |
| 16000050 | Internal error. |
| 16200001 | The caller has been released. |

**Example**

```ts
import { ServiceExtensionAbility, Want } from '@kit.AbilityKit';
import { BusinessError } from '@kit.BasicServicesKit';

class EntryAbility extends ServiceExtensionAbility {
  onCreate() {
    let want: Want = {
      deviceId: '',
      bundleName: 'com.example.myapplication',
      abilityName: 'EntryAbility'
    };
    let accountId = 100;

    try {
      this.context.startServiceExtensionAbilityWithAccount(want, accountId, (error: BusinessError) => {
        if (error.code) {
          // Process service logic errors.
          console.error(`startServiceExtensionAbilityWithAccount failed, error.code: ${error.code}, error.message: ${error.message}`);
          return;
        }
        // Carry out normal service processing.
        console.log('startServiceExtensionAbilityWithAccount succeed');
      });
    } catch (paramError) {
      // Process input parameter errors.
      console.error(`error.code: ${(paramError as BusinessError).code}, error.message: ${(paramError as BusinessError).message}`);
    }
  }
}
```

## ServiceExtensionContext.startServiceExtensionAbilityWithAccount

startServiceExtensionAbilityWithAccount(want: Want, accountId: number): Promise\<void>;

Starts a new ServiceExtensionAbility with the account ID specified. This API uses a promise to return the result.

> **NOTE**
> 
> For details about the startup rules for the components in the stage model, see [Component Startup Rules (Stage Model)](../../application-models/component-startup-rules.md). 
> Permission verification is not required when **accountId** specifies the current user.

**Required permissions**: ohos.permission.INTERACT_ACROSS_LOCAL_ACCOUNTS

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**System API**: This is a system API and cannot be called by third-party applications.

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| want | [Want](js-apis-app-ability-want.md) | Yes| Want information about the target ability.|
| accountId | number | Yes| ID of a system account. For details, see [getCreatedOsAccountsCount](../apis-basic-services-kit/js-apis-osAccount.md#getcreatedosaccountscountdeprecated-1).|

**Return value**

| Type| Description|
| -------- | -------- |
| Promise&lt;void&gt; | Promise used to return the result.|

**Error codes**

For details about the error codes, see [Universal Error Codes](../errorcode-universal.md) and [Ability Error Codes](errorcode-ability.md).

| ID| Error Message|
| ------- | -------- |
| 201 | The application does not have permission to call the interface. |
| 202 | The application is not system-app, can not use system-api. |
| 401 | Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed. |
| 16000001 | The specified ability does not exist. |
| 16000002 | Incorrect ability type. |
| 16000004 | Failed to start the invisible ability. |
| 16000005 | The specified process does not have the permission. |
| 16000006 | Cross-user operations are not allowed. |
| 16000008 | The crowdtesting application expires. |
| 16000011 | The context does not exist.        |
| 16000012 | The application is controlled.        |
| 16000013 | The application is controlled by EDM.       |
| 16000019 | No matching ability is found. |
| 16000050 | Internal error. |
| 16200001 | The caller has been released. |

**Example**

```ts
import { ServiceExtensionAbility, Want } from '@kit.AbilityKit';
import { BusinessError } from '@kit.BasicServicesKit';

class EntryAbility extends ServiceExtensionAbility {
  onCreate() {
    let want: Want = {
      deviceId: '',
      bundleName: 'com.example.myapplication',
      abilityName: 'EntryAbility'
    };
    let accountId = 100;

    try {
      this.context.startServiceExtensionAbilityWithAccount(want, accountId)
        .then((data: void) => {
          // Carry out normal service processing.
          console.log('startServiceExtensionAbilityWithAccount succeed');
        })
        .catch((error: BusinessError) => {
          // Process service logic errors.
          console.error(`startServiceExtensionAbilityWithAccount failed, error.code: ${error.code}, error.message: ${error.message}`);
        });
    } catch (paramError) {
      // Process input parameter errors.
      console.error(`error.code: ${(paramError as BusinessError).code}, error.message: ${(paramError as BusinessError).message}`);
    }
  }
}
```

## ServiceExtensionContext.startAbilityAsCaller<sup>10+<sup>

startAbilityAsCaller(want: Want, callback: AsyncCallback\<void>): void;

Starts an ability with the caller information specified. The caller information is carried in **want** and identified at the system service layer. The ability can obtain the caller information from the **want** parameter in the **onCreate** lifecycle callback. When this API is used to start an ability, the caller information carried in **want** is not overwritten by the current application information. The system service layer can obtain the initial caller information. This API uses an asynchronous callback to return the result. It can be called only by the main thread.

> **NOTE**
>
> For details about the startup rules for the components in the stage model, see [Component Startup Rules (Stage Model)](../../application-models/component-startup-rules.md).

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**System API**: This is a system API and cannot be called by third-party applications.

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| want | [Want](js-apis-app-ability-want.md)  | Yes| Want information about the target ability.|
| callback | AsyncCallback&lt;void&gt; | Yes| Callback used to return the result. If the ability is started, **err** is **undefined**; otherwise, **err** is an error object.|

**Error codes**

For details about the error codes, see [Universal Error Codes](../errorcode-universal.md) and [Ability Error Codes](errorcode-ability.md).

| ID| Error Message|
| ------- | -------- |
| 201 | The application does not have permission to call the interface. |
| 202 | The application is not system-app, can not use system-api. |
| 401 | Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed. |
| 16000001 | The specified ability does not exist. |
| 16000002 | Incorrect ability type. |
| 16000004 | Failed to start the invisible ability. |
| 16000005 | The specified process does not have the permission. |
| 16000006 | Cross-user operations are not allowed. |
| 16000008 | The crowdtesting application expires. |
| 16000009 | An ability cannot be started or stopped in Wukong mode. |
| 16000010 | The call with the continuation flag is forbidden.        |
| 16000011 | The context does not exist.        |
| 16000012 | The application is controlled.        |
| 16000013 | The application is controlled by EDM.       |
| 16000050 | Internal error. |
| 16000053 | The ability is not on the top of the UI. |
| 16000055 | Installation-free timed out. |
| 16000071 | App clone is not supported. |
| 16000072 | App clone or multi-instance is not supported. |
| 16000073 | The app clone index is invalid. |
| 16000076 | The app instance key is invalid. |
| 16000077 | The number of app instances reaches the limit. |
| 16000078 | The multi-instance is not supported. |
| 16000079 | The APP_INSTANCE_KEY cannot be specified. |
| 16000080 | Creating an instance is not supported. |
| 16000082 | The UIAbility is being started. |
| 16200001 | The caller has been released. |

**Example**

```ts
import { ServiceExtensionAbility, Want } from '@kit.AbilityKit';

class EntryAbility extends ServiceExtensionAbility {
  onCreate(want: Want) {
    // want contains the information about the caller who starts the application.
    let localWant: Want = want;
    localWant.bundleName = 'com.example.demo';
    localWant.moduleName = 'entry';
    localWant.abilityName = 'TestAbility';

    // Start a new ability using the caller information.
    this.context.startAbilityAsCaller(localWant, (err) => {
      if (err && err.code != 0) {
        console.error('startAbilityAsCaller failed, err:' + JSON.stringify(err));
      } else {
        console.log('startAbilityAsCaller success.');
      }
    })
  }
}
```

## ServiceExtensionContext.startAbilityAsCaller<sup>10+<sup>

startAbilityAsCaller(want: Want, options: StartOptions, callback: AsyncCallback\<void>): void;

Starts an ability with the caller information and start options specified. The caller information is carried in **want** and identified at the system service layer. The ability can obtain the caller information from the **want** parameter in the **onCreate** lifecycle callback. When this API is used to start an ability, the caller information carried in **want** is not overwritten by the current application information. The system service layer can obtain the initial caller information. This API uses an asynchronous callback to return the result. It can be called only by the main thread.

> **NOTE**
>
> For details about the startup rules for the components in the stage model, see [Component Startup Rules (Stage Model)](../../application-models/component-startup-rules.md).

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**System API**: This is a system API and cannot be called by third-party applications.

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| want | [Want](js-apis-app-ability-want.md)  | Yes| Want information about the target ability.|
| options | [StartOptions](js-apis-app-ability-startOptions.md) | Yes| Parameters used for starting the ability.|
| callback | AsyncCallback&lt;void&gt; | Yes| Callback used to return the result. If the ability is started, **err** is **undefined**; otherwise, **err** is an error object.|

**Error codes**

For details about the error codes, see [Universal Error Codes](../errorcode-universal.md) and [Ability Error Codes](errorcode-ability.md).

| ID| Error Message|
| ------- | -------- |
| 201 | The application does not have permission to call the interface. |
| 202 | The application is not system-app, can not use system-api. |
| 401 | Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed. |
| 16000001 | The specified ability does not exist. |
| 16000004 | Failed to start the invisible ability. |
| 16000005 | The specified process does not have the permission. |
| 16000006 | Cross-user operations are not allowed. |
| 16000008 | The crowdtesting application expires. |
| 16000009 | An ability cannot be started or stopped in Wukong mode. |
| 16000011 | The context does not exist.        |
| 16000012 | The application is controlled.        |
| 16000013 | The application is controlled by EDM.       |
| 16000050 | Internal error. |
| 16000053 | The ability is not on the top of the UI. |
| 16000055 | Installation-free timed out. |
| 16000071 | App clone is not supported. |
| 16000072 | App clone or multi-instance is not supported. |
| 16000073 | The app clone index is invalid. |
| 16000076 | The app instance key is invalid. |
| 16000077 | The number of app instances reaches the limit. |
| 16000078 | The multi-instance is not supported. |
| 16000079 | The APP_INSTANCE_KEY cannot be specified. |
| 16000080 | Creating an instance is not supported. |
| 16000082 | The UIAbility is being started. |
| 16200001 | The caller has been released. |

**Example**

```ts
import { ServiceExtensionAbility, Want, StartOptions } from '@kit.AbilityKit';

class EntryAbility extends ServiceExtensionAbility {
  onCreate(want: Want) {
    // want contains the information about the caller who starts the application.
    let localWant: Want = want;
    localWant.bundleName = 'com.example.demo';
    localWant.moduleName = 'entry';
    localWant.abilityName = 'TestAbility';

    let option: StartOptions = {
      displayId: 0
    }

    // Start a new ability using the caller information.
    this.context.startAbilityAsCaller(localWant, option, (err) => {
      if (err && err.code != 0) {
        console.error('startAbilityAsCaller failed, err:' + JSON.stringify(err));
      } else {
        console.log('startAbilityAsCaller success.');
      }
    })
  }
}
```

## ServiceExtensionContext.startAbilityAsCaller<sup>10+<sup>

startAbilityAsCaller(want: Want, options?: StartOptions): Promise\<void>;

Starts an ability with the caller information specified. The caller information is carried in **want** and identified at the system service layer. The ability can obtain the caller information from the **want** parameter in the **onCreate** lifecycle callback. When this API is used to start an ability, the caller information carried in **want** is not overwritten by the current application information. The system service layer can obtain the initial caller information. This API uses a promise to return the result. It can be called only by the main thread.

> **NOTE**
>
> For details about the startup rules for the components in the stage model, see [Component Startup Rules (Stage Model)](../../application-models/component-startup-rules.md).

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**System API**: This is a system API and cannot be called by third-party applications.

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| want | [Want](js-apis-app-ability-want.md)  | Yes| Want information about the target ability.|
| options | [StartOptions](js-apis-app-ability-startOptions.md) | No| Parameters used for starting the ability.|

**Return value**

| Type| Description|
| -------- | -------- |
| Promise&lt;void&gt; | Promise that returns no value.|

**Error codes**

For details about the error codes, see [Universal Error Codes](../errorcode-universal.md) and [Ability Error Codes](errorcode-ability.md).

| ID| Error Message|
| ------- | -------- |
| 201 | The application does not have permission to call the interface. |
| 202 | The application is not system-app, can not use system-api. |
| 401 | Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed. |
| 16000001 | The specified ability does not exist. |
| 16000002 | Incorrect ability type. |
| 16000004 | Failed to start the invisible ability. |
| 16000005 | The specified process does not have the permission. |
| 16000006 | Cross-user operations are not allowed. |
| 16000008 | The crowdtesting application expires. |
| 16000009 | An ability cannot be started or stopped in Wukong mode. |
| 16000010 | The call with the continuation flag is forbidden.        |
| 16000011 | The context does not exist.        |
| 16000012 | The application is controlled.        |
| 16000013 | The application is controlled by EDM.       |
| 16000050 | Internal error. |
| 16000053 | The ability is not on the top of the UI. |
| 16000055 | Installation-free timed out. |
| 16000071 | App clone is not supported. |
| 16000072 | App clone or multi-instance is not supported. |
| 16000073 | The app clone index is invalid. |
| 16000076 | The app instance key is invalid. |
| 16000077 | The number of app instances reaches the limit. |
| 16000078 | The multi-instance is not supported. |
| 16000079 | The APP_INSTANCE_KEY cannot be specified. |
| 16000080 | Creating an instance is not supported. |
| 16000082 | The UIAbility is being started. |
| 16200001 | The caller has been released. |

**Example**

```ts
import { ServiceExtensionAbility, Want, StartOptions } from '@kit.AbilityKit';
import { BusinessError } from '@kit.BasicServicesKit';

class EntryAbility extends ServiceExtensionAbility {
  onCreate(want: Want) {
    // want contains the information about the caller who starts the application.
    let localWant: Want = want;
    localWant.bundleName = 'com.example.demo';
    localWant.moduleName = 'entry';
    localWant.abilityName = 'TestAbility';

    let option: StartOptions = {
      displayId: 0
    };

    // Start a new ability using the caller information.
    this.context.startAbilityAsCaller(localWant, option)
      .then(() => {
        console.log('startAbilityAsCaller success.');
      })
      .catch((err: BusinessError) => {
        console.error('startAbilityAsCaller failed, err:' + JSON.stringify(err));
      })
  }
}
```

## ServiceExtensionContext.stopServiceExtensionAbility

stopServiceExtensionAbility(want: Want, callback: AsyncCallback\<void>): void;

Stops a ServiceExtensionAbility in the same application. This API uses an asynchronous callback to return the result.

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**System API**: This is a system API and cannot be called by third-party applications.

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| want | [Want](js-apis-app-ability-want.md) | Yes| Want information about the target ability.|
| callback | AsyncCallback\<void\> | Yes| Callback used to return the result.|

**Error codes**

For details about the error codes, see [Universal Error Codes](../errorcode-universal.md) and [Ability Error Codes](errorcode-ability.md).

| ID| Error Message|
| ------- | -------- |
| 201 | The application does not have permission to call the interface. |
| 202 | The application is not system-app, can not use system-api. |
| 401 | Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed. |
| 16000001 | The specified ability does not exist. |
| 16000002 | Incorrect ability type. |
| 16000004 | Failed to start the invisible ability. |
| 16000005 | The specified process does not have the permission. |
| 16000006 | Cross-user operations are not allowed. |
| 16000011 | The context does not exist.        |
| 16000050 | Internal error. |
| 16200001 | The caller has been released. |

**Example**

```ts
import { ServiceExtensionAbility, Want } from '@kit.AbilityKit';
import { BusinessError } from '@kit.BasicServicesKit';

class EntryAbility extends ServiceExtensionAbility {
  onCreate() {
    let want: Want = {
      deviceId: '',
      bundleName: 'com.example.myapplication',
      abilityName: 'EntryAbility'
    };

    try {
      this.context.stopServiceExtensionAbility(want, (error: BusinessError) => {
        if (error.code) {
          // Process service logic errors.
          console.error(`stopServiceExtensionAbility failed, error.code: ${error.code}, error.message: ${error.message}`);
          return;
        }
        // Carry out normal service processing.
        console.log('stopServiceExtensionAbility succeed');
      });
    } catch (paramError) {
      // Process input parameter errors.
      console.error(`error.code: ${(paramError as BusinessError).code}, error.message: ${(paramError as BusinessError).message}`);
    }
  }
}
```

## ServiceExtensionContext.stopServiceExtensionAbility

stopServiceExtensionAbility(want: Want): Promise\<void>;

Stops a ServiceExtensionAbility in the same application. This API uses a promise to return the result.

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**System API**: This is a system API and cannot be called by third-party applications.

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| want | [Want](js-apis-app-ability-want.md) | Yes| Want information about the target ability.|

**Return value**

| Type| Description|
| -------- | -------- |
| Promise&lt;void&gt; | Promise used to return the result.|

**Error codes**

For details about the error codes, see [Universal Error Codes](../errorcode-universal.md) and [Ability Error Codes](errorcode-ability.md).

| ID| Error Message|
| ------- | -------- |
| 201 | The application does not have permission to call the interface. |
| 202 | The application is not system-app, can not use system-api. |
| 401 | Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed. |
| 16000001 | The specified ability does not exist. |
| 16000002 | Incorrect ability type. |
| 16000004 | Failed to start the invisible ability. |
| 16000005 | The specified process does not have the permission. |
| 16000006 | Cross-user operations are not allowed. |
| 16000011 | The context does not exist.        |
| 16000050 | Internal error. |
| 16200001 | The caller has been released. |

**Example**

```ts
import { ServiceExtensionAbility, Want } from '@kit.AbilityKit';
import { BusinessError } from '@kit.BasicServicesKit';

class EntryAbility extends ServiceExtensionAbility {
  onCreate() {
    let want: Want = {
      deviceId: '',
      bundleName: 'com.example.myapplication',
      abilityName: 'EntryAbility'
    };

    try {
      this.context.stopServiceExtensionAbility(want)
        .then(() => {
          // Carry out normal service processing.
          console.log('stopServiceExtensionAbility succeed');
        })
        .catch((error: BusinessError) => {
          // Process service logic errors.
          console.error(`stopServiceExtensionAbility failed, error.code: ${error.code}, error.message: ${error.message}`);
        });
    } catch (paramError) {
      // Process input parameter errors.
      console.error(`error.code: ${(paramError as BusinessError).code}, error.message: ${(paramError as BusinessError).message}`);
    }
  }
}
```

## ServiceExtensionContext.stopServiceExtensionAbilityWithAccount

stopServiceExtensionAbilityWithAccount(want: Want, accountId: number, callback: AsyncCallback\<void>): void;

Stops a ServiceExtensionAbility in the same application with the account ID specified. This API uses an asynchronous callback to return the result.

> **NOTE**
> 
> Permission verification is not required when **accountId** specifies the current user.

**Required permissions**: ohos.permission.INTERACT_ACROSS_LOCAL_ACCOUNTS

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**System API**: This is a system API and cannot be called by third-party applications.

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| want | [Want](js-apis-app-ability-want.md) | Yes| Want information about the target ability.|
| accountId | number | Yes| ID of a system account. For details, see [getCreatedOsAccountsCount](../apis-basic-services-kit/js-apis-osAccount.md#getcreatedosaccountscountdeprecated).|
| callback | AsyncCallback\<void\> | Yes| Callback used to return the result.|

**Error codes**

For details about the error codes, see [Universal Error Codes](../errorcode-universal.md) and [Ability Error Codes](errorcode-ability.md).

| ID| Error Message|
| ------- | -------- |
| 201 | The application does not have permission to call the interface. |
| 202 | The application is not system-app, can not use system-api. |
| 401 | Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed. |
| 16000001 | The specified ability does not exist. |
| 16000002 | Incorrect ability type. |
| 16000004 | Failed to start the invisible ability. |
| 16000005 | The specified process does not have the permission. |
| 16000006 | Cross-user operations are not allowed. |
| 16000011 | The context does not exist.        |
| 16000050 | Internal error. |
| 16200001 | The caller has been released. |

**Example**

```ts
import { ServiceExtensionAbility, Want } from '@kit.AbilityKit';
import { BusinessError } from '@kit.BasicServicesKit';

class EntryAbility extends ServiceExtensionAbility {
  onCreate() {
    let want: Want = {
      deviceId: '',
      bundleName: 'com.example.myapplication',
      abilityName: 'EntryAbility'
    };
    let accountId = 100;

    try {
      this.context.stopServiceExtensionAbilityWithAccount(want, accountId, (error: BusinessError) => {
        if (error.code) {
          // Process service logic errors.
          console.error(`stopServiceExtensionAbilityWithAccount failed, error.code: ${error.code}, error.message: ${error.message}`);
          return;
        }
        // Carry out normal service processing.
        console.log('stopServiceExtensionAbilityWithAccount succeed');
      });
    } catch (paramError) {
      // Process input parameter errors.
      console.error(`error.code: ${(paramError as BusinessError).code}, error.message: ${(paramError as BusinessError).message}`);
    }
  }
}
```

## ServiceExtensionContext.stopServiceExtensionAbilityWithAccount

stopServiceExtensionAbilityWithAccount(want: Want, accountId: number): Promise\<void>;

Stops a ServiceExtensionAbility in the same application with the account ID specified. This API uses a promise to return the result.

> **NOTE**
> 
> Permission verification is not required when **accountId** specifies the current user.

**Required permissions**: ohos.permission.INTERACT_ACROSS_LOCAL_ACCOUNTS

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**System API**: This is a system API and cannot be called by third-party applications.

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| want | [Want](js-apis-app-ability-want.md) | Yes| Want information about the target ability.|
| accountId | number | Yes| ID of a system account. For details, see [getCreatedOsAccountsCount](../apis-basic-services-kit/js-apis-osAccount.md#getcreatedosaccountscountdeprecated-1).|

**Return value**

| Type| Description|
| -------- | -------- |
| Promise&lt;void&gt; | Promise used to return the result.|

**Error codes**

For details about the error codes, see [Universal Error Codes](../errorcode-universal.md) and [Ability Error Codes](errorcode-ability.md).

| ID| Error Message|
| ------- | -------- |
| 201 | The application does not have permission to call the interface. |
| 202 | The application is not system-app, can not use system-api. |
| 401 | Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed. |
| 16000001 | The specified ability does not exist. |
| 16000002 | Incorrect ability type. |
| 16000004 | Failed to start the invisible ability. |
| 16000005 | The specified process does not have the permission. |
| 16000006 | Cross-user operations are not allowed. |
| 16000011 | The context does not exist.        |
| 16000050 | Internal error. |
| 16200001 | The caller has been released. |

**Example**

```ts
import { ServiceExtensionAbility, Want } from '@kit.AbilityKit';
import { BusinessError } from '@kit.BasicServicesKit';

class EntryAbility extends ServiceExtensionAbility {
  onCreate() {
    let want: Want = {
      deviceId: '',
      bundleName: 'com.example.myapplication',
      abilityName: 'EntryAbility'
    };
    let accountId = 100;

    try {
      this.context.stopServiceExtensionAbilityWithAccount(want, accountId)
        .then(() => {
          // Carry out normal service processing.
          console.log('stopServiceExtensionAbilityWithAccount succeed');
        })
        .catch((error: BusinessError) => {
          // Process service logic errors.
          console.error(`stopServiceExtensionAbilityWithAccount failed, error.code: ${error.code}, error.message: ${error.message}`);
        });
    } catch (paramError) {
      // Process input parameter errors.
      console.error(`error.code: ${(paramError as BusinessError).code}, error.message: ${(paramError as BusinessError).message}`);
    }
  }
}
```

## ServiceExtensionContext.terminateSelf

terminateSelf(callback: AsyncCallback&lt;void&gt;): void;

Terminates this ability. This API uses an asynchronous callback to return the result. It can be called only by the main thread.

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**System API**: This is a system API and cannot be called by third-party applications.

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| callback | AsyncCallback&lt;void&gt; | Yes| Callback used to return the result.|

**Error codes**

For details about the error codes, see [Universal Error Codes](../errorcode-universal.md) and [Ability Error Codes](errorcode-ability.md).

| ID| Error Message|
| ------- | -------- |
| 401 | Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed. |
| 16000001 | The specified ability does not exist. |
| 16000004 | Failed to start the invisible ability. |
| 16000005 | The specified process does not have the permission. |
| 16000009 | An ability cannot be started or stopped in Wukong mode. |
| 16000011 | The context does not exist.        |
| 16000050 | Internal error. |

**Example**

```ts
import { ServiceExtensionAbility } from '@kit.AbilityKit';
import { BusinessError } from '@kit.BasicServicesKit';

class EntryAbility extends ServiceExtensionAbility {
  onCreate() {
    this.context.terminateSelf((error: BusinessError) => {
      if (error.code) {
        // Process service logic errors.
        console.error(`terminateSelf failed, error.code: ${error.code}, error.message: ${error.message}`);
        return;
      }
      // Carry out normal service processing.
      console.log('terminateSelf succeed');
    });
  }
}
```

## ServiceExtensionContext.terminateSelf

terminateSelf(): Promise&lt;void&gt;;

Terminates this ability. This API uses a promise to return the result. It can be called only by the main thread.

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**System API**: This is a system API and cannot be called by third-party applications.

**Return value**

| Type| Description|
| -------- | -------- |
| Promise&lt;void&gt; | Promise used to return the result.|

**Error codes**

For details about the error codes, see [Ability Error Codes](errorcode-ability.md).

| ID| Error Message|
| ------- | -------------------------------- |
| 16000001 | The specified ability does not exist. |
| 16000004 | Failed to start the invisible ability. |
| 16000005 | The specified process does not have the permission. |
| 16000009 | An ability cannot be started or stopped in Wukong mode. |
| 16000011 | The context does not exist.        |
| 16000050 | Internal error. |

**Example**

```ts
import { ServiceExtensionAbility } from '@kit.AbilityKit';
import { BusinessError } from '@kit.BasicServicesKit';

class EntryAbility extends ServiceExtensionAbility {
  onCreate() {
    this.context.terminateSelf().then(() => {
      // Carry out normal service processing.
      console.log('terminateSelf succeed');
    }).catch((error: BusinessError) => {
      // Process service logic errors.
      console.error(`terminateSelf failed, error.code: ${error.code}, error.message: ${error.message}`);
    });
  }
}
```

## ServiceExtensionContext.connectServiceExtensionAbility

connectServiceExtensionAbility(want: Want, options: ConnectOptions): number;

Connects this ability to a ServiceExtensionAbility. It can be called only by the main thread.

> **NOTE**
>
> For details about the startup rules for the components in the stage model, see [Component Startup Rules (Stage Model)](../../application-models/component-startup-rules.md).

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**System API**: This is a system API and cannot be called by third-party applications.

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| want | [Want](js-apis-app-ability-want.md)  | Yes| Want information about the target ability, such as the ability name and bundle name.|
| options | [ConnectOptions](js-apis-inner-ability-connectOptions.md) | Yes| Callback used to return the information indicating that the connection is successful, interrupted, or failed.|

**Return value**

| Type| Description|
| -------- | -------- |
| number | A number, based on which the connection will be interrupted.|

**Error codes**

For details about the error codes, see [Universal Error Codes](../errorcode-universal.md) and [Ability Error Codes](errorcode-ability.md).

| ID| Error Message|
| ------- | -------- |
| 201 | The application does not have permission to call the interface. |
| 401 | Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed. |
| 16000001 | The specified ability does not exist. |
| 16000002 | Incorrect ability type. |
| 16000004 | Failed to start the invisible ability. |
| 16000005 | The specified process does not have the permission. |
| 16000006 | Cross-user operations are not allowed. |
| 16000008 | The crowdtesting application expires. |
| 16000053 | The ability is not on the top of the UI. |
| 16000055 | Installation-free timed out. |
| 16000011 | The context does not exist.        |
| 16000050 | Internal error. |

**Example**

```ts
import { ServiceExtensionAbility, Want, common } from '@kit.AbilityKit';
import { rpc } from '@kit.IPCKit';
import { BusinessError } from '@kit.BasicServicesKit';

let commRemote: rpc.IRemoteObject; // Release the instance when the connection is disconnected.

class EntryAbility extends ServiceExtensionAbility {
  onCreate() {
    let want: Want = {
      bundleName: 'com.example.myapp',
      abilityName: 'MyAbility'
    };
    let options: common.ConnectOptions = {
      onConnect(elementName, remote) {
        commRemote = remote;
        console.log('----------- onConnect -----------');
      },
      onDisconnect(elementName) {
        console.log('----------- onDisconnect -----------');
      },
      onFailed(code) {
        console.error('----------- onFailed -----------');
      }
    };
    let connection: number;

    try {
      connection = this.context.connectServiceExtensionAbility(want, options);
    } catch (paramError) {
      // Process input parameter errors.
      console.error(`error.code: ${(paramError as BusinessError).code}, error.message: ${(paramError as BusinessError).message}`);
    }
  }
}
```

## ServiceExtensionContext.connectServiceExtensionAbilityWithAccount

connectServiceExtensionAbilityWithAccount(want: Want, accountId: number, options: ConnectOptions): number;

Connects this ability to a ServiceExtensionAbility of a given account. It can be called only by the main thread.

> **NOTE**
>
> For details about the startup rules for the components in the stage model, see [Component Startup Rules (Stage Model)](../../application-models/component-startup-rules.md). 
> Permission verification is not required when **accountId** specifies the current user.

**Required permissions**: ohos.permission.INTERACT_ACROSS_LOCAL_ACCOUNTS

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**System API**: This is a system API and cannot be called by third-party applications.

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| want | [Want](js-apis-app-ability-want.md) | Yes| Want information about the target ability.|
| accountId | number | Yes| ID of a system account. For details, see [getCreatedOsAccountsCount](../apis-basic-services-kit/js-apis-osAccount.md#getcreatedosaccountscountdeprecated).|
| options | ConnectOptions | Yes| Remote object instance.|

**Return value**

| Type| Description|
| -------- | -------- |
| number | Result code of the connection.|

**Error codes**

For details about the error codes, see [Universal Error Codes](../errorcode-universal.md) and [Ability Error Codes](errorcode-ability.md).

| ID| Error Message|
| ------- | -------- |
| 201 | The application does not have permission to call the interface. |
| 202 | The application is not system-app, can not use system-api. |
| 401 | Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed. |
| 16000001 | The specified ability does not exist. |
| 16000002 | Incorrect ability type. |
| 16000004 | Failed to start the invisible ability. |
| 16000005 | The specified process does not have the permission. |
| 16000006 | Cross-user operations are not allowed. |
| 16000008 | The crowdtesting application expires. |
| 16000053 | The ability is not on the top of the UI. |
| 16000055 | Installation-free timed out. |
| 16000011 | The context does not exist.        |
| 16000050 | Internal error. |

**Example**

```ts
import { ServiceExtensionAbility, Want, common } from '@kit.AbilityKit';
import { rpc } from '@kit.IPCKit';
import { BusinessError } from '@kit.BasicServicesKit';

let commRemote: rpc.IRemoteObject; // Release the instance when the connection is disconnected.

class EntryAbility extends ServiceExtensionAbility {
  onCreate() {
    let want: Want = {
      deviceId: '',
      bundleName: 'com.example.myapplication',
      abilityName: 'EntryAbility'
    };
    let accountId = 100;
    let options: common.ConnectOptions = {
      onConnect(elementName, remote) {
        commRemote = remote;
        console.log('----------- onConnect -----------');
      },
      onDisconnect(elementName) {
        console.log('----------- onDisconnect -----------');
      },
      onFailed(code) {
        console.log('----------- onFailed -----------');
      }
    };
    let connection: number;

    try {
      connection = this.context.connectServiceExtensionAbilityWithAccount(want, accountId, options);
    } catch (paramError) {
      // Process input parameter errors.
      console.error(`error.code: ${(paramError as BusinessError).code}, error.message: ${(paramError as BusinessError).message}`);
    }
  }
}
```

## ServiceExtensionContext.disconnectServiceExtensionAbility

disconnectServiceExtensionAbility(connection: number, callback:AsyncCallback&lt;void&gt;): void;

Disconnects this ability from a ServiceExtensionAbility and after the successful disconnection, sets the remote object returned upon the connection to void. This API uses an asynchronous callback to return the result. It can be called only by the main thread.

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**System API**: This is a system API and cannot be called by third-party applications.

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| connection | number | Yes| Number returned after **connectServiceExtensionAbility** is called.|
| callback | AsyncCallback&lt;void&gt; | Yes| Callback used to return the result.|

**Error codes**

For details about the error codes, see [Universal Error Codes](../errorcode-universal.md) and [Ability Error Codes](errorcode-ability.md).

| ID| Error Message|
| ------- | -------- |
| 401 | Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed. |
| 16000011 | The context does not exist.        |
| 16000050 | Internal error. |

**Example**

```ts
import { ServiceExtensionAbility } from '@kit.AbilityKit';
import { rpc } from '@kit.IPCKit';
import { BusinessError } from '@kit.BasicServicesKit';

let commRemote: rpc.IRemoteObject | null; // Release the instance when the connection is disconnected.

class EntryAbility extends ServiceExtensionAbility {
  onCreate() {
    // connection is the return value of connectServiceExtensionAbility.
    let connection = 1;
    try {
      this.context.disconnectServiceExtensionAbility(connection, (error: BusinessError) => {
        commRemote = null;
        if (error.code) {
          // Process service logic errors.
          console.error(`disconnectServiceExtensionAbility failed, error.code: ${error.code}, error.message: ${error.message}`);
          return;
        }
        // Carry out normal service processing.
        console.log('disconnectServiceExtensionAbility succeed');
      });
    } catch (paramError) {
      commRemote = null;
      // Process input parameter errors.
      console.error(`error.code: ${(paramError as BusinessError).code}, error.message: ${(paramError as BusinessError).message}`);
    }
  }
}
```

## ServiceExtensionContext.disconnectServiceExtensionAbility

disconnectServiceExtensionAbility(connection: number): Promise&lt;void&gt;;

Disconnects this ability from a ServiceExtensionAbility and after the successful disconnection, sets the remote object returned upon the connection to void. This API uses a promise to return the result. It can be called only by the main thread.

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**System API**: This is a system API and cannot be called by third-party applications.

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| connection | number | Yes| Number returned after **connectServiceExtensionAbility** is called.|

**Return value**

| Type| Description|
| -------- | -------- |
| Promise&lt;void&gt; | Promise used to return the result.|

**Error codes**

For details about the error codes, see [Universal Error Codes](../errorcode-universal.md) and [Ability Error Codes](errorcode-ability.md).

| ID| Error Message|
| ------- | -------- |
| 401 | Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed. |
| 16000011 | The context does not exist.        |
| 16000050 | Internal error. |

**Example**

```ts
import { ServiceExtensionAbility } from '@kit.AbilityKit';
import { rpc } from '@kit.IPCKit';
import { BusinessError } from '@kit.BasicServicesKit';

let commRemote: rpc.IRemoteObject | null; // Release the instance when the connection is disconnected.

class EntryAbility extends ServiceExtensionAbility {
  onCreate() {
    // connection is the return value of connectServiceExtensionAbility.
    let connection = 1;
    try {
      this.context.disconnectServiceExtensionAbility(connection)
        .then(() => {
          commRemote = null;
          // Carry out normal service processing.
          console.log('disconnectServiceExtensionAbility succeed');
        })
        .catch((error: BusinessError) => {
          commRemote = null;
          // Process service logic errors.
          console.error(`disconnectServiceExtensionAbility failed, error.code: ${error.code}, error.message: ${error.message}`);
        });
    } catch (paramError) {
      commRemote = null;
      // Process input parameter errors.
      console.error(`error.code: ${(paramError as BusinessError).code}, error.message: ${(paramError as BusinessError).message}`);
    }
  }
}
```

## ServiceExtensionContext.startAbilityByCall

startAbilityByCall(want: Want): Promise&lt;Caller&gt;;

Starts an ability in the foreground or background and obtains the caller object for communicating with the ability. It can be called only by the main thread.

This API cannot be used to start the UIAbility with the launch type set to [specified](../../application-models/uiability-launch-type.md#specified).

Observe the following when using this API:
 - If an application running in the background needs to call this API to start an ability, it must have the **ohos.permission.START_ABILITIES_FROM_BACKGROUND** permission.
 - If **exported** of the target ability is **false** in cross-application scenarios, the caller must have the **ohos.permission.START_INVISIBLE_ABILITY** permission.
 - The rules for using this API in the same-device and cross-device scenarios are different. For details, see [Component Startup Rules (Stage Model)](../../application-models/component-startup-rules.md).

**Required permissions**: ohos.permission.ABILITY_BACKGROUND_COMMUNICATION

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**System API**: This is a system API and cannot be called by third-party applications.

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| want | [Want](js-apis-app-ability-want.md) | Yes| Information about the ability to start, including **abilityName**, **moduleName**, **bundleName**, **deviceId**, and **parameters** (optional). If **parameters** is left blank or null, the ability is started in the background.|

**Return value**

| Type| Description|
| -------- | -------- |
| Promise&lt;Caller&gt; | Promise used to return the caller object to communicate with.|

**Error codes**

For details about the error codes, see [Universal Error Codes](../errorcode-universal.md) and [Ability Error Codes](errorcode-ability.md).

| ID| Error Message|
| ------- | -------- |
| 201 | The application does not have permission to call the interface. |
| 401 | Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed. |
| 16000001 | The specified ability does not exist. |
| 16000002 | Incorrect ability type. |
| 16000004 | Failed to start the invisible ability. |
| 16000005 | Static permission denied. The specified process does not have the permission. |
| 16000006 | Cross-user operations are not allowed. |
| 16000008 | The crowdtesting application expires. |
| 16000011 | The context does not exist. |
| 16000050 | Internal error. |
| 16200001 | The caller has been released.        |

**Example**

Start an ability in the background.

```ts
import { ServiceExtensionAbility, Caller, Want } from '@kit.AbilityKit';
import { BusinessError } from '@kit.BasicServicesKit';

class EntryAbility extends ServiceExtensionAbility {
  onCreate() {
    let caller: Caller;
    // Start an ability in the background by not passing parameters.
    let wantBackground: Want = {
      bundleName: 'com.example.myservice',
      moduleName: 'entry',
      abilityName: 'EntryAbility',
      deviceId: ''
    };

    try {
      this.context.startAbilityByCall(wantBackground)
        .then((obj: Caller) => {
          // Carry out normal service processing.
          caller = obj;
          console.log('startAbilityByCall succeed');
        }).catch((error: BusinessError) => {
        // Process service logic errors.
        console.error(`startAbilityByCall failed, error.code: ${error.code}, error.message: ${error.message}`);
      });
    } catch (paramError) {
      // Process input parameter errors.
      console.error(`error.code: ${(paramError as BusinessError).code}, error.message: ${(paramError as BusinessError).message}`);
    }
  }
}
```

Start an ability in the foreground.

```ts
import { ServiceExtensionAbility, Caller, Want } from '@kit.AbilityKit';
import { BusinessError } from '@kit.BasicServicesKit';

class EntryAbility extends ServiceExtensionAbility {
  onCreate() {
    let caller: Caller;
    // Start an ability in the foreground with 'ohos.aafwk.param.callAbilityToForeground' in parameters set to true.
    let wantForeground: Want = {
      bundleName: 'com.example.myservice',
      moduleName: 'entry',
      abilityName: 'EntryAbility',
      deviceId: '',
      parameters: {
        'ohos.aafwk.param.callAbilityToForeground': true
      }
    };

    try {
      this.context.startAbilityByCall(wantForeground)
        .then((obj: Caller) => {
          // Carry out normal service processing.
          caller = obj;
          console.log('startAbilityByCall succeed');
        }).catch((error: BusinessError) => {
        // Process service logic errors.
        console.error(`startAbilityByCall failed, error.code: ${error.code}, error.message: ${error.message}`);
      });
    } catch (paramError) {
      // Process input parameter errors.
      console.error(`error.code: ${(paramError as BusinessError).code}, error.message: ${(paramError as BusinessError).message}`);
    }
  }
}
```
## ServiceExtensionContext.startRecentAbility

startRecentAbility(want: Want, callback: AsyncCallback\<void>): void;

Starts an ability. If the ability has multiple instances, the latest instance is started. This API uses an asynchronous callback to return the result. It can be called only by the main thread.

> **NOTE**
>
> For details about the startup rules for the components in the stage model, see [Component Startup Rules (Stage Model)](../../application-models/component-startup-rules.md).

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**System API**: This is a system API and cannot be called by third-party applications.

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| want | [Want](js-apis-app-ability-want.md) | Yes| Want information about the target ability.|
| callback | AsyncCallback\<void> | Yes| Callback used to return the result.|

**Error codes**

For details about the error codes, see [Universal Error Codes](../errorcode-universal.md) and [Ability Error Codes](errorcode-ability.md).

| ID| Error Message|
| ------- | -------- |
| 201 | The application does not have permission to call the interface. |
| 401 | Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed. |
| 16000001 | The specified ability does not exist. |
| 16000002 | Incorrect ability type. |
| 16000004 | Failed to start the invisible ability. |
| 16000005 | The specified process does not have the permission. |
| 16000006 | Cross-user operations are not allowed. |
| 16000008 | The crowdtesting application expires. |
| 16000009 | An ability cannot be started or stopped in Wukong mode. |
| 16000010 | The call with the continuation flag is forbidden. |
| 16000011 | The context does not exist. |
| 16000050 | Internal error. |
| 16000053 | The ability is not on the top of the UI. |
| 16000055 | Installation-free timed out. |
| 16000082 | The UIAbility is being started. |
| 16200001 | The caller has been released. |

**Example**

```ts
import { ServiceExtensionAbility, Want } from '@kit.AbilityKit';
import { BusinessError } from '@kit.BasicServicesKit';

class EntryAbility extends ServiceExtensionAbility {
  onCreate() {
    let want: Want = {
      bundleName: 'com.example.myapplication',
      abilityName: 'EntryAbility'
    };

    try {
      this.context.startRecentAbility(want, (err: BusinessError) => {
        if (err.code) {
          // Process service logic errors.
          console.error(`startRecentAbility failed, code is ${err.code}, message is ${err.message}`);
          return;
        }
        // Carry out normal service processing.
        console.info('startRecentAbility succeed');
      });
    } catch (err) {
      // Process input parameter errors.
      let code = (err as BusinessError).code;
      let message = (err as BusinessError).message;
      console.error(`startRecentAbility failed, code is ${code}, message is ${message}`);
    }
  }
}
```
## ServiceExtensionContext.startRecentAbility

startRecentAbility(want: Want, options: StartOptions, callback: AsyncCallback\<void>): void;

Starts an ability with the start options specified. If the ability has multiple instances, the latest instance is started. This API uses an asynchronous callback to return the result.
You can use this API to carry start options. It can be called only by the main thread.

> **NOTE**
>
> For details about the startup rules for the components in the stage model, see [Component Startup Rules (Stage Model)](../../application-models/component-startup-rules.md).

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**System API**: This is a system API and cannot be called by third-party applications.

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| want | [Want](js-apis-app-ability-want.md) | Yes| Want information about the target ability.|
| options | [StartOptions](js-apis-app-ability-startOptions.md) | Yes| Parameters used for starting the ability.|
| callback | AsyncCallback\<void> | Yes| Callback used to return the result.|

**Error codes**

For details about the error codes, see [Universal Error Codes](../errorcode-universal.md) and [Ability Error Codes](errorcode-ability.md).

| ID| Error Message|
| ------- | -------- |
| 201 | The application does not have permission to call the interface. |
| 401 | Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed. |
| 16000001 | The specified ability does not exist. |
| 16000002 | Incorrect ability type. |
| 16000004 | Failed to start the invisible ability. |
| 16000005 | The specified process does not have the permission. |
| 16000006 | Cross-user operations are not allowed. |
| 16000008 | The crowdtesting application expires. |
| 16000009 | An ability cannot be started or stopped in Wukong mode. |
| 16000010 | The call with the continuation flag is forbidden. |
| 16000011 | The context does not exist. |
| 16000050 | Internal error. |
| 16000053 | The ability is not on the top of the UI. |
| 16000055 | Installation-free timed out. |
| 16000082 | The UIAbility is being started. |
| 16200001 | The caller has been released. |

**Example**

```ts
import { ServiceExtensionAbility, Want, StartOptions } from '@kit.AbilityKit';
import { BusinessError } from '@kit.BasicServicesKit';

class EntryAbility extends ServiceExtensionAbility {
  onCreate() {
    let want: Want = {
      deviceId: '',
      bundleName: 'com.example.myapplication',
      abilityName: 'EntryAbility'
    };
    let options: StartOptions = {
      windowMode: 0
    };

    try {
      this.context.startRecentAbility(want, options, (err: BusinessError) => {
        if (err.code) {
          // Process service logic errors.
          console.error(`startRecentAbility failed, code is ${err.code}, message is ${err.message}`);
          return;
        }
        // Carry out normal service processing.
        console.info('startRecentAbility succeed');
      });
    } catch (err) {
      // Process input parameter errors.
      let code = (err as BusinessError).code;
      let message = (err as BusinessError).message;
      console.error(`startRecentAbility failed, code is ${code}, message is ${message}`);
    }
  }
}
```
## ServiceExtensionContext.startRecentAbility

startRecentAbility(want: Want, options?: StartOptions): Promise\<void>;

Starts an ability. If the ability has multiple instances, the latest instance is started.
This API uses a promise to return the result. It can be called only by the main thread.

> **NOTE**
>
> For details about the startup rules for the components in the stage model, see [Component Startup Rules (Stage Model)](../../application-models/component-startup-rules.md).

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**System API**: This is a system API and cannot be called by third-party applications.

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| want | [Want](js-apis-app-ability-want.md) | Yes| Want information about the target ability.|
| options | [StartOptions](js-apis-app-ability-startOptions.md) | No| Parameters used for starting the ability.|

**Error codes**

For details about the error codes, see [Universal Error Codes](../errorcode-universal.md) and [Ability Error Codes](errorcode-ability.md).

| ID| Error Message|
| ------- | -------- |
| 201 | The application does not have permission to call the interface. |
| 401 | Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed. |
| 16000001 | The specified ability does not exist. |
| 16000002 | Incorrect ability type. |
| 16000004 | Failed to start the invisible ability. |
| 16000005 | The specified process does not have the permission. |
| 16000006 | Cross-user operations are not allowed. |
| 16000008 | The crowdtesting application expires. |
| 16000009 | An ability cannot be started or stopped in Wukong mode. |
| 16000010 | The call with the continuation flag is forbidden. |
| 16000011 | The context does not exist. |
| 16000050 | Internal error. |
| 16000053 | The ability is not on the top of the UI. |
| 16000055 | Installation-free timed out. |
| 16000082 | The UIAbility is being started. |
| 16200001 | The caller has been released. |

**Example**

```ts
import { ServiceExtensionAbility, Want, StartOptions } from '@kit.AbilityKit';
import { BusinessError } from '@kit.BasicServicesKit';

class EntryAbility extends ServiceExtensionAbility {
  onCreate() {
    let want: Want = {
      bundleName: 'com.example.myapplication',
      abilityName: 'EntryAbility'
    };
    let options: StartOptions = {
      windowMode: 0,
    };

    try {
      this.context.startRecentAbility(want, options)
        .then(() => {
          // Carry out normal service processing.
          console.info('startRecentAbility succeed');
        })
        .catch((err: BusinessError) => {
          // Process service logic errors.
          console.error(`startRecentAbility failed, code is ${err.code}, message is ${err.message}`);
        });
    } catch (err) {
      // Process input parameter errors.
      let code = (err as BusinessError).code;
      let message = (err as BusinessError).message;
      console.error(`startRecentAbility failed, code is ${code}, message is ${message}`);
    }
  }
}
```

## ServiceExtensionContext.startAbilityByCallWithAccount<sup>10+</sup>

startAbilityByCallWithAccount(want: Want, accountId: number): Promise&lt;Caller&gt;;

Starts an ability with the account ID specified and obtains the caller object for communicating with the ability. It can be called only by the main thread.

This API cannot be used to start the UIAbility with the launch type set to [specified](../../application-models/uiability-launch-type.md#specified).

Observe the following when using this API:
 - If an application needs to call this API to start an ability that belongs to another user, it must have the **ohos.permission.ABILITY_BACKGROUND_COMMUNICATION** and **ohos.permission.INTERACT_ACROSS_LOCAL_ACCOUNTS** permissions.
 - If an application running in the background needs to call this API to start an ability, it must have the **ohos.permission.START_ABILITIES_FROM_BACKGROUND** permission.
 - If **exported** of the target ability is **false** in cross-application scenarios, the caller must have the **ohos.permission.START_INVISIBLE_ABILITY** permission.
 - The rules for using this API in the same-device and cross-device scenarios are different. For details, see [Component Startup Rules (Stage Model)](../../application-models/component-startup-rules.md).

**Required permissions**: ohos.permission.ABILITY_BACKGROUND_COMMUNICATION and ohos.permission.INTERACT_ACROSS_LOCAL_ACCOUNTS

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**System API**: This is a system API and cannot be called by third-party applications.

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| want | [Want](js-apis-app-ability-want.md) | Yes| Information about the ability to start, including **abilityName**, **moduleName**, **bundleName**, **deviceId** (optional), and **parameters** (optional). If **deviceId** is left blank or null, the local ability is started. If **parameters** is left blank or null, the ability is started in the background.|
| accountId | number | Yes| ID of a system account. The value **-1** indicates the current user. For details, see [getCreatedOsAccountsCount](../apis-basic-services-kit/js-apis-osAccount.md#getcreatedosaccountscountdeprecated-1).|

**Return value**

| Type| Description|
| -------- | -------- |
| Promise&lt;Caller&gt; | Promise used to return the caller object to communicate with.|

**Error codes**

For details about the error codes, see [Universal Error Codes](../errorcode-universal.md) and [Ability Error Codes](errorcode-ability.md).

| ID| Error Message|
| ------- | -------- |
| 201 | The application does not have permission to call the interface. |
| 202 | The application is not system-app, can not use system-api. |
| 401 | Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed. |
| 16000001 | The specified ability does not exist. |
| 16000002 | Incorrect ability type. |
| 16000004 | Failed to start the invisible ability. |
| 16000005 | Static permission denied. The specified process does not have the permission. |
| 16000006 | Cross-user operations are not allowed. |
| 16000008 | The crowdtesting application expires. |
| 16000011 | The context does not exist. |
| 16000012 | The application is controlled.        |
| 16000013 | The application is controlled by EDM.       |
| 16000050 | Internal error. |
| 16200001 | The caller has been released.        |

**Example**

```ts
import { ServiceExtensionAbility, Want, Caller } from '@kit.AbilityKit';
import { BusinessError } from '@kit.BasicServicesKit';

class EntryAbility extends ServiceExtensionAbility {
  onCreate() {
    let caller: Caller;
    // ID of a system account. The value -1 indicates the current user.
    let accountId = -1;
    // Specify the ability to start.
    let want: Want = {
      bundleName: 'com.acts.actscalleeabilityrely',
      moduleName: 'entry',
      abilityName: 'EntryAbility',
      deviceId: '',
      parameters: {
        // If the value of 'ohos.aafwk.param.callAbilityToForeground' is true, the ability is started in the foreground. If the value is false or not set, the ability is started in the background.
        'ohos.aafwk.param.callAbilityToForeground': true
      }
    };

    try {
      this.context.startAbilityByCallWithAccount(want, accountId)
        .then((obj: Caller) => {
          // Carry out normal service processing.
          caller = obj;
          console.log('startAbilityByCallWithAccount succeed');
        }).catch((error: BusinessError) => {
        // Process service logic errors.
        console.error(`startAbilityByCallWithAccount failed, error.code: ${error.code}, error.message: ${error.message}`);
      });
    } catch (paramError) {
      // Process input parameter errors.
      console.error(`error.code: ${(paramError as BusinessError).code}, error.message: ${(paramError as BusinessError).message}`);
    }
  }
}
```

## ServiceExtensionContext.requestModalUIExtension<sup>11+<sup>

requestModalUIExtension(pickerWant: Want): Promise\<void>

Requests the specified foreground application to start the UIExtensionAbility of the corresponding type. The foreground application is specified by **bundleName** in **want.parameters**. If **bundleName** is left unspecified, or if the application specified by **bundleName** is not running in the foreground or does not exist, the UIExtensionAbility is directly started on the system UI. The UIExtensionAbility to start is determined by the combination of the **bundleName**, **abilityName**, and **moduleName** fields in **want**, and its type is determined by the **ability.want.params.uiExtensionType** field in **want.parameters**. This API uses a promise to return the result. It can be called only by the main thread.

Before starting the UIExtensionAbility, ensure that the foreground application has finished page initialization. Otherwise, the UIExtensionAbility fails to start and the error message "uiContent is nullptr" is displayed. The application can determine the time to start the UIExtensionAbility by listening for the page loading status. After the page initialization is successful, the key log information "UIContentImpl: focus again" is recorded.

> **NOTE**
>
> For details about the startup rules for the components in the stage model, see [Component Startup Rules (Stage Model)](../../application-models/component-startup-rules.md).

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**System API**: This is a system API.

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| pickerWant | [Want](js-apis-app-ability-want.md)  | Yes| Want information used to start the UIExtensionAbility.|

**Return value**

| Type| Description|
| -------- | -------- |
| Promise&lt;void&gt; | Promise that returns no value.|

**Error codes**

For details about the error codes, see [Universal Error Codes](../errorcode-universal.md) and [Ability Error Codes](errorcode-ability.md).

| ID| Error Message|
| ------- | -------- |
| 202 | The application is not system-app, can not use system-api. |
| 401 | Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed. |
| 16000050 | Internal error. |

**Example**

```ts
import { ServiceExtensionAbility, Want } from '@kit.AbilityKit';
import { BusinessError } from '@kit.BasicServicesKit';

class ServiceExtension extends ServiceExtensionAbility {
  onCreate() {
    let pickerWant: Want = {
      bundleName: 'com.example.myapplication',
      abilityName: 'UIExtAbility',
      moduleName: 'entry_test',
      parameters: {
        'bundleName': 'com.example.myapplication',
        // The value is the same as the value of type configured for com.example.myapplication.UIExtAbility.
        'ability.want.params.uiExtensionType': 'sys/commonUI'
      }
    };

    try {
      this.context.requestModalUIExtension(pickerWant)
        .then(() => {
          // Carry out normal service processing.
          console.info('requestModalUIExtension succeed');
        })
        .catch((err: BusinessError) => {
          // Process service logic errors.
          console.error(`requestModalUIExtension failed, code is ${err.code}, message is ${err.message}`);
        });
    } catch (err) {
      // Process input parameter errors.
      let code = (err as BusinessError).code;
      let message = (err as BusinessError).message;
      console.error(`requestModalUIExtension failed, code is ${code}, message is ${message}`);
    }
  }
}
```

## ServiceExtensionContext.requestModalUIExtension<sup>11+<sup>

requestModalUIExtension(pickerWant: Want, callback: AsyncCallback\<void>): void

Requests the specified foreground application to start the UIExtensionAbility of the corresponding type. The foreground application is specified by **bundleName** in **want.parameters**. If **bundleName** is left unspecified, or if the application specified by **bundleName** is not running in the foreground or does not exist, the UIExtensionAbility is directly started on the system UI. The UIExtensionAbility to start is determined by the combination of the **bundleName**, **abilityName**, and **moduleName** fields in **want**, and its type is determined by the **ability.want.params.uiExtensionType** field in **want.parameters**. This API uses an asynchronous callback to return the result. It can be called only by the main thread.

Before starting the UIExtensionAbility, ensure that the foreground application has finished page initialization. Otherwise, the UIExtensionAbility fails to start and the error message "uiContent is nullptr" is displayed. The application can determine the time to start the UIExtensionAbility by listening for the page loading status. After the page initialization is successful, the key log information "UIContentImpl: focus again" is recorded.

> **NOTE**
>
> For details about the startup rules for the components in the stage model, see [Component Startup Rules (Stage Model)](../../application-models/component-startup-rules.md).

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**System API**: This is a system API.

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| pickerWant | [Want](js-apis-app-ability-want.md)  | Yes| Want information used to start the UIExtensionAbility.|
| callback | AsyncCallback&lt;void&gt; | Yes| Callback used to return the result. If the UIExtensionAbility is started, **err** is **undefined**; otherwise, **err** is an error object.|

**Error codes**

For details about the error codes, see [Universal Error Codes](../errorcode-universal.md) and [Ability Error Codes](errorcode-ability.md).

| ID| Error Message|
| ------- | -------- |
| 202 | The application is not system-app, can not use system-api. |
| 401 | Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed. |
| 16000050 | Internal error. |

**Example**

```ts
import { ServiceExtensionAbility, Want } from '@kit.AbilityKit';
import { BusinessError } from '@kit.BasicServicesKit';

class ServiceExtension extends ServiceExtensionAbility {
  onCreate() {
    let pickerWant: Want = {
      bundleName: 'com.example.myapplication',
      abilityName: 'com.example.myapplication.UIExtAbility',
      moduleName: 'entry_test',
      parameters: {
        'bundleName': 'com.example.myapplication',
        // The value is the same as the value of type configured for com.example.myapplication.UIExtAbility.
        'ability.want.params.uiExtensionType': 'sys/commonUI'
      }
    };

    try {
      this.context.requestModalUIExtension(pickerWant, (err: BusinessError) => {
        if (err.code) {
          // Process service logic errors.
          console.error(`requestModalUIExtension failed, code is ${err.code}, message is ${err.message}`);
          return;
        }
        // Carry out normal service processing.
        console.info('requestModalUIExtension succeed');
      });
    } catch (err) {
      // Process input parameter errors.
      let code = (err as BusinessError).code;
      let message = (err as BusinessError).message;
      console.error(`requestModalUIExtension failed, code is ${code}, message is ${message}`);
    }
  }
}
```

## ServiceExtensionContext.openLink<sup>12+<sup>
openLink(link:string, options?: OpenLinkOptions): Promise&lt;void&gt;

Starts a UIAbility through App Linking. This API uses a promise to return the result. It can be called only by the main thread.

A URL in the standard format is passed in to the **link** field to start the target UIAbility based on the implicit Want matching rules. The target UIAbility must have the following filter characteristics to process links of App Linking:
- The **actions** field contains **ohos.want.action.viewData**.
- The **entities** field contains **entity.system.browsable**.
- The **uris** field contains elements whose **scheme** is **https** and **domainVerify** is **true**.

If an input parameter is invalid, for example, a mandatory parameter is not set or the URL set in **link** is not in the standard format, an exception is thrown. If the parameter verification is successful but an error occurs when starting the target UIAbility, the error information is returned through promise.

> **NOTE**
>
> For details about the startup rules for the components in the stage model, see [Component Startup Rules (Stage Model)](../../application-models/component-startup-rules.md).

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**System API**: This is a system API.

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| link | string | Yes| URL to open, which must be in the standard format.|
| options | [OpenLinkOptions](js-apis-app-ability-openLinkOptions.md) | No| Options of the URL.|

**Return value**

| Type| Description|
| -------- | -------- |
| Promise&lt;void&gt; | Promise that returns no value.|

**Error codes**

For details about the error codes, see [Universal Error Codes](../errorcode-universal.md) and [Ability Error Codes](errorcode-ability.md).

| ID| Error Message|
| ------- | -------- |
| 201 | The application does not have permission to call the interface. |
| 202 | The application is not system-app, can not use system-api. |
| 401 | Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed. |
| 16000001 | The specified ability does not exist. |
| 16000002 | Incorrect ability type. |
| 16000004 | Failed to start the invisible ability. |
| 16000005 | The specified process does not have the permission. |
| 16000006 | Cross-user operations are not allowed. |
| 16000008 | The crowdtesting application expires. |
| 16000009 | An ability cannot be started or stopped in Wukong mode. |
| 16000010 | The call with the continuation flag is forbidden.        |
| 16000011 | The context does not exist.        |
| 16000012 | The application is controlled.        |
| 16000013 | The application is controlled by EDM.       |
| 16000019 | No matching ability is found. |
| 16200001 | The caller has been released. |
| 16000082 | The UIAbility is being started. |

**Example**

```ts
import { ServiceExtensionAbility, Want, OpenLinkOptions } from '@kit.AbilityKit';
import { BusinessError } from '@kit.BasicServicesKit';

function log(info: string) {
  console.error(`[ServiceExtApp]:: ${JSON.stringify(info)}`);
}

export default class ServiceExtAbility extends ServiceExtensionAbility {
  onCreate(want: Want) {
    log(`ServiceExtAbility OnCreate`);
  }

  onRequest(want: Want, startId: number) {
    log(`ServiceExtAbility onRequest`);
    let link: string = 'https://www.example.com';
    let openLinkOptions: OpenLinkOptions = {
      appLinkingOnly: false
    };
    try {
      this.context.openLink(
        link,
        openLinkOptions
      ).then(() => {
        log(`open link success.`);
      }).catch((err: BusinessError) => {
        log(`open link failed, errCode ${JSON.stringify(err.code)}`);
      });
    }
    catch (e) {
      log(`exception occured, errCode ${JSON.stringify(e.code)}`);
    }
  }

  onDestroy() {
    log(`ServiceExtAbility onDestroy`);
  }
}
```

## ServiceExtensionContext.preStartMission<sup>12+<sup>
preStartMission(bundleName:string, moduleName: string, abilitName: string, startTime: string): Promise&lt;void&gt;

Starts an atomic service and pre-opens the window, with the loading box skipped. This API uses a promise to return the result.

If parameter verification is successful but the atomic service fails to start, you need to implement an exception mechanism to capture the error.

**Required permissions**: ohos.permission.PRE_START_ATOMIC_SERVICE

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**System API**: This is a system API.

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| bundleName | string | Yes| Bundle name of the atomic service.|
| moduleName | string | Yes| Module name of the atomic service.|
| abilityName | string | Yes| Ability name of the atomic service.|
| startTime | string | Yes| Start time to open the atomic service, in milliseconds.|


**Return value**

| Type| Description|
| -------- | -------- |
| Promise&lt;void&gt; | Promise that returns no value.|

**Error codes**

For details about the error codes, see [Universal Error Codes](../errorcode-universal.md) and [Ability Error Codes](errorcode-ability.md).

| ID| Error Message|
| ------- | -------- |
| 201 | The application does not have permission to call the interface. |
| 202 | The application is not system-app, can not use system-api. |
| 401 | Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed. |
| 16300007 | The target free install task does not exist. |
| 16000011 | The context does not exist.        |

**Example**

```ts
import { ServiceExtensionAbility, Want } from '@kit.AbilityKit';
import { BusinessError } from '@kit.BasicServicesKit';

function log(info: string) {
  console.error(`[ServiceExtApp]:: ${JSON.stringify(info)}`);
}

export default class ServiceExtAbility extends ServiceExtensionAbility {
  onCreate(want: Want) {
    log(`ServiceExtAbility OnCreate`);
  }

  onRequest(want: Want, startId: number) {
    log(`ServiceExtAbility onRequest`);
    try {
      this.context.preStartMission(
        want.bundleName,
        want.moduleName,
        want.abilityName,
        want.parameters["ohos.aafwk.param.startTime"]
      ).then(() => {
        log(`pre-start mission success.`);
      }).catch((err: BusinessError) => {
        log(`pre-start mission failed, errCode ${JSON.stringify(err.code)}`);
      });
    }
    catch (e) {
      log(`exception occured, errCode ${JSON.stringify(e.code)}`);
    }
  }

  onDestroy() {
    log(`ServiceExtAbility onDestroy`);
  }
}
```

## ServiceExtensionContext.startUIServiceExtensionAbility<sup>13+<sup>
startUIServiceExtensionAbility(want: Want): Promise&lt;void&gt;

Starts a new [UIServiceExtensionAbility](js-apis-app-ability-uiServiceExtensionAbility-sys.md). This API uses a promise to return the result.


> **NOTE**
>
> For details about the startup rules for the components in the stage model, see [Component Startup Rules (Stage Model)](../../application-models/component-startup-rules.md).
>

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**System API**: This is a system API.

**Parameters**
| Name| Type| Read Only| Optional| Description                |
| ------ | ---- | ---- | -------------------- | -------------------- |
| want   | [Want](js-apis-app-ability-want.md) | Yes | No| [Want](js-apis-app-ability-want.md) used to pass the information about the ability to start, such as the ability name and bundle name.|

**Return value**

| Type               | Description                                  |
| ------------------- | -------------------------------------- |
| Promise&lt;void&gt; | Promise that returns no value.|

**Error codes**

For details about the error codes, see [Universal Error Codes](../errorcode-universal.md) and [Ability Error Codes](errorcode-ability.md).
| ID| Error Message                                                             |
| -------- | ---------------------------------------------------------------------|
| 201      | The application does not have permission to call the interface.      |
| 202      | The application is not system-app, can not use system-api.           |
| 401      | Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed. |
| 801      | The Ability is not supported.                       |
| 16000001 | The specified ability does not exist.               |
| 16000002 | Incorrect ability type.                             |
| 16000004 | Failed to start the invisible ability.              |
| 16000005 | The specified process does not have the permission. |
| 16000006 | Cross-user operations are not allowed.              |
| 16000008 | The crowdtesting application expires.               |
| 16000011 | The context does not exist.                         |
| 16000012 | The application is controlled.                      |
| 16000013 | The application is controlled by EDM.               |
| 16000019 | No matching ability is found.                       |
| 16000050 | Internal error.                                     |
| 16200001 | The caller has been released.                       |

**Example**

```ts
import { BusinessError } from '@ohos.base';
import { ServiceExtensionAbility, Want } from '@kit.AbilityKit';

export default class MyServiceExtensionAbility extends ServiceExtensionAbility {
  onRequest(want: Want, startId: number) {
    const startWant: Want = {
      bundleName: 'com.example.myapplication',
      abilityName: 'UIServiceExtensionAbility'
    }
    // Start a UIServiceExtensionAbility.
    this.context.startUIServiceExtensionAbility(startWant).then(() => {
      console.info('succeeded');
    }).catch((error: BusinessError) => {
      console.error(`error code: ${error.code}, error essage : ${error.message}`);
    })
  }
}
```