# @ohos.resourceschedule.backgroundTaskManager (Background Task Management)

The **backgroundTaskManager** module provides APIs to request background tasks. You can use the APIs to request transient tasks, continuous tasks, or efficiency resources to prevent the application process from being terminated or suspended when your application is switched to the background.

>  **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.


## Modules to Import

```js
import backgroundTaskManager from '@ohos.resourceschedule.backgroundTaskManager';  
```

## backgroundTaskManager.requestSuspendDelay

requestSuspendDelay(reason: string, callback: Callback<void>): DelaySuspendInfo

Requests a transient task.

>  **NOTE**
> 
> The maximum duration of a transient task is 3 minutes in normal cases. In the case of a [low battery](js-apis-battery-info.md), the maximum duration is decreased to 1 minute.

**System capability**: SystemCapability.ResourceSchedule.BackgroundTaskManager.TransientTask

**Parameters**

| Name     | Type                  | Mandatory  | Description                            |
| -------- | -------------------- | ---- | ------------------------------ |
| reason   | string               | Yes   | Reason for requesting the transient task.                    |
| callback | Callback<void> | Yes   | Callback used to notify the application that the transient task is about to time out. Generally, the callback is invoked 6 seconds before the timeout.|

**Return value**

| Type                                   | Description       |
| ------------------------------------- | --------- |
| [DelaySuspendInfo](#delaysuspendinfo) | Information about the transient task.|

**Error codes**

For details about the error codes, see [backgroundTaskManager Error Codes](../errorcodes/errorcode-backgroundTaskMgr.md).

| ID | Error Message            |
| ---- | --------------------- |
| 9800001 | Memory operation failed. |
| 9800002 | Parcel operation failed. |
| 9800003 | Inner transact failed. | |
| 9800004 | System service operation failed. |
| 9900001 | Caller information verification failed. |
| 9900002 | Background task verification failed. |

**Example**

  ```js
  import backgroundTaskManager from '@ohos.resourceschedule.backgroundTaskManager';  

  let myReason = 'test requestSuspendDelay';
  try {
    let delayInfo = backgroundTaskManager.requestSuspendDelay(myReason, () => {
        console.info("Request suspension delay will time out.");
    })
    let id = delayInfo.requestId;
    let time = delayInfo.actualDelayTime;
    console.info("The requestId is: " + id);
    console.info("The actualDelayTime is: " + time);
  } catch (error) {
    console.error(`requestSuspendDelay failed. code is ${error.code} message is ${error.message}`);
  }
  ```


## backgroundTaskManager.getRemainingDelayTime

getRemainingDelayTime(requestId: number, callback: AsyncCallback<number>): void

Obtains the remaining time of a transient task. This API uses an asynchronous callback to return the result.

**System capability**: SystemCapability.ResourceSchedule.BackgroundTaskManager.TransientTask

**Parameters**

| Name      | Type                         | Mandatory  | Description                                      |
| --------- | --------------------------- | ---- | ---------------------------------------- |
| requestId | number                      | Yes   | Request ID of the transient task.                              |
| callback  | AsyncCallback<number> | Yes   | Callback used to return the remaining time, in milliseconds.|

**Error codes**

For details about the error codes, see [backgroundTaskManager Error Codes](../errorcodes/errorcode-backgroundTaskMgr.md).

| ID | Error Message            |
| ---- | --------------------- |
| 9800001 | Memory operation failed. |
| 9800002 | Parcel operation failed. |
| 9800003 | Inner transact failed.  |
| 9800004 | System service operation failed. |
| 9900001 | Caller information verification failed. |
| 9900002 | Background task verification failed. |


**Example**

  ```js
  import backgroundTaskManager from '@ohos.resourceschedule.backgroundTaskManager';  

  let id = 1;
  try {
    backgroundTaskManager.getRemainingDelayTime(id, (error, res) => {
        if(error) {
            console.error(`callback => Operation getRemainingDelayTime failed. code is ${error.code} message is ${error.message}`);
        } else {
            console.log('callback => Operation getRemainingDelayTime succeeded. Data: ' + JSON.stringify(res));
        }
    })
  } catch (error) {
    console.error(`callback => Operation getRemainingDelayTime failed. code is ${error.code} message is ${error.message}`);
  }
  ```


## backgroundTaskManager.getRemainingDelayTime

getRemainingDelayTime(requestId: number): Promise<number>

Obtains the remaining time of a transient task. This API uses a promise to return the result.

**System capability**: SystemCapability.ResourceSchedule.BackgroundTaskManager.TransientTask

**Parameters**

| Name      | Type    | Mandatory  | Description        |
| --------- | ------ | ---- | ---------- |
| requestId | number | Yes   | Request ID of the transient task.|

**Return value**

| Type                   | Description                                      |
| --------------------- | ---------------------------------------- |
| Promise<number> | Promise used to return the remaining time, in milliseconds.|

**Error codes**

For details about the error codes, see [backgroundTaskManager Error Codes](../errorcodes/errorcode-backgroundTaskMgr.md).

| ID | Error Message            |
| ---- | --------------------- |
| 9800001 | Memory operation failed. |
| 9800002 | Parcel operation failed. |
| 9800003 | Inner transact failed. | |
| 9800004 | System service operation failed. |
| 9900001 | Caller information verification failed. |
| 9900002 | Background task verification failed. |

**Example**

  ```js
  import backgroundTaskManager from '@ohos.resourceschedule.backgroundTaskManager';  

  let id = 1;
  try {
    backgroundTaskManager.getRemainingDelayTime(id).then( res => {
        console.log('promise => Operation getRemainingDelayTime succeeded. Data: ' + JSON.stringify(res));
    }).catch( error => {
        console.error(`promise => Operation getRemainingDelayTime failed. code is ${error.code} message is ${error.message}`);
    })
  } catch (error) {
    console.error(`promise => Operation getRemainingDelayTime failed. code is ${error.code} message is ${error.message}`);
  }
  ```


## backgroundTaskManager.cancelSuspendDelay

cancelSuspendDelay(requestId: number): void

Cancels a transient task.

**System capability**: SystemCapability.ResourceSchedule.BackgroundTaskManager.TransientTask

**Parameters**

| Name      | Type    | Mandatory  | Description        |
| --------- | ------ | ---- | ---------- |
| requestId | number | Yes   | Request ID of the transient task.|

**Error codes**

For details about the error codes, see [backgroundTaskManager Error Codes](../errorcodes/errorcode-backgroundTaskMgr.md).

| ID | Error Message            |
| ---- | --------------------- |
| 9800001 | Memory operation failed. |
| 9800002 | Parcel operation failed. |
| 9800003 | Inner transact failed. | |
| 9800004 | System service operation failed. |
| 9900001 | Caller information verification failed. |
| 9900002 | Background task verification failed. |

**Example**

  ```js
  import backgroundTaskManager from '@ohos.resourceschedule.backgroundTaskManager';  

  let id = 1;
  try {
    backgroundTaskManager.cancelSuspendDelay(id);
  } catch (error) {
    console.error(`cancelSuspendDelay failed. code is ${error.code} message is ${error.message}`);
  }
  ```

## backgroundTaskManager.startBackgroundRunning

startBackgroundRunning(context: Context, bgMode: BackgroundMode, wantAgent: WantAgent, callback: AsyncCallback<void>): void

Requests a continuous task. This API uses an asynchronous callback to return the result.

**Required permissions**: ohos.permission.KEEP_BACKGROUND_RUNNING

**System capability**: SystemCapability.ResourceSchedule.BackgroundTaskManager.ContinuousTask

**Parameters**

| Name      | Type                                | Mandatory  | Description                                      |
| --------- | ---------------------------------- | ---- | ---------------------------------------- |
| context   | Context                            | Yes   | Application context.<br>For details about the application context of the FA model, see [Context](js-apis-inner-app-context.md).<br>For details about the application context of the stage model, see [Context](js-apis-inner-application-context.md).|
| bgMode    | [BackgroundMode](#backgroundmode) | Yes   | Continuous task mode.                             |
| wantAgent | [WantAgent](js-apis-app-ability-wantAgent.md) | Yes   | Notification parameters, which are used to specify the target page that is redirected to when a continuous task notification is clicked.          |
| callback  | AsyncCallback&lt;void&gt;          | Yes   | Callback used to return the result. If the continuous task is requested, **err** is **undefined**. Otherwise, **err** is an error object.   |

**Error codes**

For details about the error codes, see [backgroundTaskManager Error Codes](../errorcodes/errorcode-backgroundTaskMgr.md).

| ID | Error Message            |
| ---- | --------------------- |
| 9800001 | Memory operation failed. |
| 9800002 | Parcel operation failed. |
| 9800003 | Inner transact failed. | |
| 9800004 | System service operation failed. |
| 9800005 | Background task verification failed. |
| 9800006 | Notification verification failed. |
| 9800007 | Task storage failed. |

**Example**

```js
import UIAbility from '@ohos.app.ability.UIAbility';
import backgroundTaskManager from '@ohos.resourceschedule.backgroundTaskManager';  
import wantAgent from '@ohos.app.ability.wantAgent';

function callback(error, data) {
    if (error) {
        console.error(`Operation startBackgroundRunning failed. code is ${error.code} message is ${error.message}`);
    } else {
        console.info("Operation startBackgroundRunning succeeded");
    }
}

export default class EntryAbility extends UIAbility {
    onCreate(want, launchParam) {
        let wantAgentInfo = {
            wants: [
                {
                    bundleName: "com.example.myapplication",
                    abilityName: "EntryAbility"
                }
            ],
            operationType: wantAgent.OperationType.START_ABILITY,
            requestCode: 0,
            wantAgentFlags: [wantAgent.WantAgentFlags.UPDATE_PRESENT_FLAG]
        };

        try {
            wantAgent.getWantAgent(wantAgentInfo).then((wantAgentObj) => {
                try {
                    backgroundTaskManager.startBackgroundRunning(this.context,
                        backgroundTaskManager.BackgroundMode.LOCATION, wantAgentObj, callback)
                } catch (error) {
                    console.error(`Operation startBackgroundRunning failed. code is ${error.code} message is ${error.message}`);
                }
            });
        } catch (error) {
            console.error(`Operation getWantAgent failed. code is ${error.code} message is ${error.message}`);
        }
    }
};
```

## backgroundTaskManager.startBackgroundRunning

startBackgroundRunning(context: Context, bgMode: BackgroundMode, wantAgent: WantAgent): Promise&lt;void&gt;

Requests a continuous task. This API uses a promise to return the result.

**Required permissions**: ohos.permission.KEEP_BACKGROUND_RUNNING

**System capability**: SystemCapability.ResourceSchedule.BackgroundTaskManager.ContinuousTask

**Parameters**

| Name      | Type                                | Mandatory  | Description                                      |
| --------- | ---------------------------------- | ---- | ---------------------------------------- |
| context   | Context                            | Yes   | Application context.<br>For details about the application context of the FA model, see [Context](js-apis-inner-app-context.md).<br>For details about the application context of the stage model, see [Context](js-apis-inner-application-context.md).|
| bgMode    | [BackgroundMode](#backgroundmode) | Yes   | Continuous task mode.                             |
| wantAgent | [WantAgent](js-apis-app-ability-wantAgent.md) | Yes   | Notification parameters, which are used to specify the target page that is redirected to when a continuous task notification is clicked.                |

**Return value**

| Type            | Description              |
| -------------- | ---------------- |
| Promise\<void> | Promise that returns no value.|

**Error codes**

For details about the error codes, see [backgroundTaskManager Error Codes](../errorcodes/errorcode-backgroundTaskMgr.md).

| ID | Error Message            |
| ---- | --------------------- |
| 9800001 | Memory operation failed. |
| 9800002 | Parcel operation failed. |
| 9800003 | Inner transact failed. | |
| 9800004 | System service operation failed. |
| 9800005 | Background task verification failed. |
| 9800006 | Notification verification failed. |
| 9800007 | Task storage failed. |

**Example**

```js
import UIAbility from '@ohos.app.ability.UIAbility';
import backgroundTaskManager from '@ohos.resourceschedule.backgroundTaskManager'; 
import wantAgent from '@ohos.app.ability.wantAgent';

export default class EntryAbility extends UIAbility {
    onCreate(want, launchParam) {
        let wantAgentInfo = {
            wants: [
                {
                    bundleName: "com.example.myapplication",
                    abilityName: "EntryAbility"
                }
            ],
            operationType: wantAgent.OperationType.START_ABILITY,
            requestCode: 0,
            wantAgentFlags: [wantAgent.WantAgentFlags.UPDATE_PRESENT_FLAG]
        };

        try {
            wantAgent.getWantAgent(wantAgentInfo).then((wantAgentObj) => {
                try {
                    backgroundTaskManager.startBackgroundRunning(this.context,
                        backgroundTaskManager.BackgroundMode.LOCATION, wantAgentObj).then(() => {
                        console.info("Operation startBackgroundRunning succeeded");
                    }).catch((error) => {
                        console.error(`Operation startBackgroundRunning failed. code is ${error.code} message is ${error.message}`);
                    });
                } catch (error) {
                    console.error(`Operation startBackgroundRunning failed. code is ${error.code} message is ${error.message}`);
                }
            });
        } catch (error) {
            console.error(`Operation getWantAgent failed. code is ${error.code} message is ${error.message}`);
        }
    }
};
```

## backgroundTaskManager.stopBackgroundRunning

stopBackgroundRunning(context: Context, callback: AsyncCallback&lt;void&gt;): void

Cancels a continuous task. This API uses an asynchronous callback to return the result.

**System capability**: SystemCapability.ResourceSchedule.BackgroundTaskManager.ContinuousTask

**Parameters**

| Name     | Type                       | Mandatory  | Description                                      |
| -------- | ------------------------- | ---- | ---------------------------------------- |
| context  | Context                   | Yes   | Application context.<br>For details about the application context of the FA model, see [Context](js-apis-inner-app-context.md).<br>For details about the application context of the stage model, see [Context](js-apis-inner-application-context.md).|
| callback | AsyncCallback&lt;void&gt; | Yes   | Callback used to return the result. If the continuous task is canceled, **err** is **undefined**. Otherwise, **err** is an error object.|

**Error codes**

For details about the error codes, see [backgroundTaskManager Error Codes](../errorcodes/errorcode-backgroundTaskMgr.md).

| ID | Error Message            |
| ---- | --------------------- |
| 9800001 | Memory operation failed. |
| 9800002 | Parcel operation failed. |
| 9800003 | Inner transact failed. | |
| 9800004 | System service operation failed. |
| 9800005 | Background task verification failed. |
| 9800006 | Notification verification failed. |
| 9800007 | Task storage failed. |

**Example**

```js
import UIAbility from '@ohos.app.ability.UIAbility';
import backgroundTaskManager from '@ohos.resourceschedule.backgroundTaskManager';  

function callback(error, data) {
    if (error) {
        console.error(`Operation stopBackgroundRunning failed. code is ${error.code} message is ${error.message}`);
    } else {
        console.info("Operation stopBackgroundRunning succeeded");
    }
}

export default class EntryAbility extends UIAbility {
    onCreate(want, launchParam) {
        try {
            backgroundTaskManager.stopBackgroundRunning(this.context, callback);
        } catch (error) {
            console.error(`Operation stopBackgroundRunning failed. code is ${error.code} message is ${error.message}`);
        }
    }
};
```

## backgroundTaskManager.stopBackgroundRunning

stopBackgroundRunning(context: Context): Promise&lt;void&gt;

Cancels a continuous task. This API uses a promise to return the result.

**System capability**: SystemCapability.ResourceSchedule.BackgroundTaskManager.ContinuousTask

**Parameters**

| Name    | Type     | Mandatory  | Description                                      |
| ------- | ------- | ---- | ---------------------------------------- |
| context | Context | Yes   | Application context.<br>For details about the application context of the FA model, see [Context](js-apis-inner-app-context.md).<br>For details about the application context of the stage model, see [Context](js-apis-inner-application-context.md).|

**Return value**

| Type            | Description              |
| -------------- | ---------------- |
| Promise\<void> | Promise that returns no value.|

**Error codes**

For details about the error codes, see [backgroundTaskManager Error Codes](../errorcodes/errorcode-backgroundTaskMgr.md).

| ID | Error Message            |
| ---- | --------------------- |
| 9800001 | Memory operation failed. |
| 9800002 | Parcel operation failed. |
| 9800003 | Inner transact failed. | |
| 9800004 | System service operation failed. |
| 9800005 | Background task verification failed. |
| 9800006 | Notification verification failed. |
| 9800007 | Task storage failed. |

**Example**

```js
import UIAbility from '@ohos.app.ability.UIAbility';
import backgroundTaskManager from '@ohos.resourceschedule.backgroundTaskManager';  

export default class EntryAbility extends UIAbility {
    onCreate(want, launchParam) {
        try {
            backgroundTaskManager.stopBackgroundRunning(this.context).then(() => {
                console.info("Operation stopBackgroundRunning succeeded");
            }).catch((error) => {
                console.error(`Operation stopBackgroundRunning failed. code is ${error.code} message is ${error.message}`);
            });
        } catch (error) {
            console.error(`Operation stopBackgroundRunning failed. code is ${error.code} message is ${error.message}`);
        }
    }
};
```

## backgroundTaskManager.applyEfficiencyResources

applyEfficiencyResources(request: EfficiencyResourcesRequest): void

Requests efficiency resources.

**System capability**: SystemCapability.ResourceSchedule.BackgroundTaskManager.EfficiencyResourcesApply

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

**Parameters**

| Name    | Type     | Mandatory  | Description                                      |
| ------- | ------- | ---- | ---------------------------------------- |
| request | [EfficiencyResourcesRequest](#efficiencyresourcesrequest) | Yes   | Necessary information carried in the request, including the resource type and timeout interval.|


**Error codes**

For details about the error codes, see [backgroundTaskManager Error Codes](../errorcodes/errorcode-backgroundTaskMgr.md).

| ID | Error Message            |
| ---- | --------------------- |
| 9800001 | Memory operation failed. |
| 9800002 | Parcel operation failed. |
| 9800003 | Inner transact failed. | |
| 9800004 | System service operation failed. |
| 18700001 | Caller information verification failed. |

**Example**

```js
import backgroundTaskManager from '@ohos.resourceschedule.backgroundTaskManager';  

let request = {
    resourceTypes: backgroundTaskManager.ResourceType.CPU,
    isApply: true,
    timeOut: 0,
    reason: "apply",
    isPersist: true,
    isProcess: false,
};
try {
    backgroundTaskManager.applyEfficiencyResources(request);
    console.info("applyEfficiencyResources success. ");
} catch (error) {
    console.error(`applyEfficiencyResources failed. code is ${error.code} message is ${error.message}`);
}
```

## backgroundTaskManager.resetAllEfficiencyResources

resetAllEfficiencyResources(): void

Releases all efficiency resources.

**System capability**: SystemCapability.ResourceSchedule.BackgroundTaskManager.EfficiencyResourcesApply

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

**Error codes**

For details about the error codes, see [backgroundTaskManager Error Codes](../errorcodes/errorcode-backgroundTaskMgr.md).

| ID | Error Message            |
| ---- | --------------------- |
| 9800001 | Memory operation failed. |
| 9800002 | Parcel operation failed. |
| 9800003 | Inner transact failed. | |
| 9800004 | System service operation failed. |
| 18700001 | Caller information verification failed. |

**Example**

```js
import backgroundTaskManager from '@ohos.resourceschedule.backgroundTaskManager';  

try {
    backgroundTaskManager.resetAllEfficiencyResources();
} catch (error) {
    console.error(`resetAllEfficiencyResources failed. code is ${error.code} message is ${error.message}`);
}
```

## DelaySuspendInfo

Defines the information about the transient task.

**System capability**: SystemCapability.ResourceSchedule.BackgroundTaskManager.TransientTask

| Name            | Type    | Mandatory  | Description                                      |
| --------------- | ------ | ---- | ---------------------------------------- |
| requestId       | number | Yes   | Request ID of the transient task.                              |
| actualDelayTime | number | Yes   | Actual duration of the transient task that the application requests, in milliseconds.<br>The maximum duration of a transient task is 3 minutes in normal cases. In the case of a [low battery](js-apis-battery-info.md), the maximum duration is decreased to 1 minute.|

## BackgroundMode

Enumerates the continuous task modes.

**System capability**: SystemCapability.ResourceSchedule.BackgroundTaskManager.ContinuousTask

| Name                    | Value | Description                   |
| ----------------------- | ---- | --------------------- |
| DATA_TRANSFER           | 1    | Data transfer.                 |
| AUDIO_PLAYBACK          | 2    | Audio playback.                 |
| AUDIO_RECORDING         | 3    | Audio recording.                   |
| LOCATION                | 4    | Positioning and navigation.                 |
| BLUETOOTH_INTERACTION   | 5    | Bluetooth-related task.                 |
| MULTI_DEVICE_CONNECTION | 6    | Multi-device connection.                |
| WIFI_INTERACTION        | 7    | WLAN-related.<br>**System API**: This is a system API.|
| VOIP                    | 8    |Audio and video calls.<br>**System API**: This is a system API.|
| TASK_KEEPING            | 9    | Computing task (for specific devices only).       |

## EfficiencyResourcesRequest

Describes the parameters for requesting efficiency resources.

**System capability**: SystemCapability.ResourceSchedule.BackgroundTaskManager.EfficiencyResourcesApply

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

| Name            | Type    | Mandatory  | Description                                      |
| --------------- | ------ | ---- | ---------------------------------------- |
| resourceTypes   | number  | Yes   | Type of the resource to request.                              |
| isApply         | boolean | Yes   | Whether the request is used to apply for resources.<br>The value **true** means that the request is used to apply for resources, and **false** means that the request is used to release resources.|
| timeOut         | number  | Yes   | Duration for which the resource will be used, in milliseconds.               |
| isPersist       | boolean | No   | Whether the resource is permanently held. The default value is **false**.<br>The value **true** means that the resource is permanently held, and **false** means the resource is held within a given period of time.|
| isProcess       | boolean | No   | Whether the request is initiated by a process. The default value is **false**.<br>The value **true** means that the request is initiated by a process, and **false** means that the request is initiated by an application.        |
| reason          | string  | Yes   | Reason for requesting the resource.               |

## ResourceType

Enumerates the efficiency resource types.

**System capability**: SystemCapability.ResourceSchedule.BackgroundTaskManager.EfficiencyResourcesApply

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

| Name                    | Value | Description                   |
| ----------------------- | ---- | --------------------- |
| CPU                     | 1    | CPU resource. Such type of resource prevents an application from being suspended.            |
| COMMON_EVENT            | 2    | Common event resource. Such type of resource ensures that an application in the suspended state can receive common events.|
| TIMER                   | 4    | Timer resource. Such type of resource ensures that an application in the suspended state can be woken up by system timers.|
| WORK_SCHEDULER          | 8    | Deferred task resource. Such type of resource provides a loose control policy for an application.|
| BLUETOOTH               | 16   | Bluetooth resource. Such type of resource ensures that an application in the suspended state can be woken up by Bluetooth-related events.|
| GPS                     | 32   | GPS resource. Such type of resource ensures that an application in the suspended state can be woken up by GPS-related events.|
| AUDIO                   | 64   | Audio resource. Such type of resource prevents an application from being suspended when the application has an audio being played.|
| RUNNING_LOCK<sup>10+</sup> | 128 | RUNNING_LOCK resources are not proxied when the application is suspended.|
| SENSOR<sup>10+</sup> | 256 | Sensor callbacks are not intercepted.|