harmony 鸿蒙@ohos.resourceschedule.backgroundTaskManager (Background Task Management)

  • 2022-12-05
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@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

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, 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 Information about the transient task.

Error codes

For details about the error codes, see backgroundTaskManager Error Codes.

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

import { BusinessError } from '@ohos.base';

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 as BusinessError).code} message is ${(error as BusinessError).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.

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

import { BusinessError } from '@ohos.base';

let id = 1;
backgroundTaskManager.getRemainingDelayTime(id, (error: BusinessError, res: number) => {
    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));
    }
})

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.

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

import { BusinessError } from '@ohos.base';

let id = 1;
backgroundTaskManager.getRemainingDelayTime(id).then((res: number) => {
    console.log('promise => Operation getRemainingDelayTime succeeded. Data: ' + JSON.stringify(res));
}).catch((error: BusinessError) => {
    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.

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

  import { BusinessError } from '@ohos.base';

  let id = 1;
  try {
    backgroundTaskManager.cancelSuspendDelay(id);
  } catch (error) {
    console.error(`cancelSuspendDelay failed. code is ${(error as BusinessError).code} message is ${(error as BusinessError).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.
For details about the application context of the FA model, see Context.
For details about the application context of the stage model, see Context.
bgMode BackgroundMode Yes Continuous task mode.
wantAgent WantAgent Yes Notification parameters, which are used to specify the target page that is redirected to when a continuous task notification is clicked.
callback AsyncCallback<void> 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.

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

import UIAbility from '@ohos.app.ability.UIAbility';
import backgroundTaskManager from '@ohos.resourceschedule.backgroundTaskManager';  
import wantAgent, { WantAgent } from '@ohos.app.ability.wantAgent';
import Want from '@ohos.app.ability.Want';
import AbilityConstant from '@ohos.app.ability.AbilityConstant';
import { BusinessError } from '@ohos.base';

function callback(error: BusinessError, data: void) {
    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: Want, launchParam: AbilityConstant.LaunchParam) {
        let wantAgentInfo: wantAgent.WantAgentInfo = {
            // List of operations to be executed after the notification is clicked.
            wants: [
                {
                    bundleName: "com.example.myapplication",
                    abilityName: "EntryAbility"
                }
            ],
            // Type of the operation to perform after the notification is clicked.
            operationType: wantAgent.OperationType.START_ABILITY,
            // Custom request code.
            requestCode: 0,
            // Execution attribute of the operation to perform after the notification is clicked.
            wantAgentFlags: [wantAgent.WantAgentFlags.UPDATE_PRESENT_FLAG]
        };

        try {
            // Obtain the WantAgent object by using the getWantAgent API of the wantAgent module.
            wantAgent.getWantAgent(wantAgentInfo).then((wantAgentObj: WantAgent) => {
                try {
                    backgroundTaskManager.startBackgroundRunning(this.context,
                        backgroundTaskManager.BackgroundMode.LOCATION, wantAgentObj, callback)
                } catch (error) {
                    console.error(`Operation startBackgroundRunning failed. code is ${(error as BusinessError).code} message is ${(error as BusinessError).message}`);
                }
            });
        } catch (error) {
            console.error(`Operation getWantAgent failed. code is ${(error as BusinessError).code} message is ${(error as BusinessError).message}`);
        }
    }
};

backgroundTaskManager.startBackgroundRunning

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

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.
For details about the application context of the FA model, see Context.
For details about the application context of the stage model, see Context.
bgMode BackgroundMode Yes Continuous task mode.
wantAgent WantAgent 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.

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

import UIAbility from '@ohos.app.ability.UIAbility';
import backgroundTaskManager from '@ohos.resourceschedule.backgroundTaskManager'; 
import wantAgent, { WantAgent } from '@ohos.app.ability.wantAgent';
import Want from '@ohos.app.ability.Want';
import AbilityConstant from '@ohos.app.ability.AbilityConstant';
import { BusinessError } from '@ohos.base';

export default class EntryAbility extends UIAbility {
    onCreate(want: Want, launchParam: AbilityConstant.LaunchParam) {
        let wantAgentInfo: wantAgent.WantAgentInfo = {
            // List of operations to be executed after the notification is clicked.
            wants: [
                {
                    bundleName: "com.example.myapplication",
                    abilityName: "EntryAbility"
                }
            ],
            // Type of the operation to perform after the notification is clicked.
            operationType: wantAgent.OperationType.START_ABILITY,
            // Custom request code.
            requestCode: 0,
            // Execution attribute of the operation to perform after the notification is clicked.
            wantAgentFlags: [wantAgent.WantAgentFlags.UPDATE_PRESENT_FLAG]
        };

        try {
            // Obtain the WantAgent object by using the getWantAgent API of the wantAgent module.
            wantAgent.getWantAgent(wantAgentInfo).then((wantAgentObj: WantAgent) => {
                try {
                    backgroundTaskManager.startBackgroundRunning(this.context,
                        backgroundTaskManager.BackgroundMode.LOCATION, wantAgentObj).then(() => {
                        console.info("Operation startBackgroundRunning succeeded");
                    }).catch((error: BusinessError) => {
                        console.error(`Operation startBackgroundRunning failed. code is ${error.code} message is ${error.message}`);
                    });
                } catch (error) {
                    console.error(`Operation startBackgroundRunning failed. code is ${(error as BusinessError).code} message is ${(error as BusinessError).message}`);
                }
            });
        } catch (error) {
            console.error(`Operation getWantAgent failed. code is ${(error as BusinessError).code} message is ${(error as BusinessError).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.
For details about the application context of the FA model, see Context.
For details about the application context of the stage model, see Context.
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.

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

import UIAbility from '@ohos.app.ability.UIAbility';
import backgroundTaskManager from '@ohos.resourceschedule.backgroundTaskManager';  
import Want from '@ohos.app.ability.Want';
import AbilityConstant from '@ohos.app.ability.AbilityConstant';
import { BusinessError } from '@ohos.base';

function callback(error: BusinessError, data: void) {
    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: Want, launchParam: AbilityConstant.LaunchParam) {
        try {
            backgroundTaskManager.stopBackgroundRunning(this.context, callback);
        } catch (error) {
            console.error(`Operation stopBackgroundRunning failed. code is ${(error as BusinessError).code} message is ${(error as BusinessError).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.
For details about the application context of the FA model, see Context.
For details about the application context of the stage model, see Context.

Return value

Type Description
Promise<void> Promise that returns no value.

Error codes

For details about the error codes, see backgroundTaskManager Error Codes.

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

import UIAbility from '@ohos.app.ability.UIAbility';
import backgroundTaskManager from '@ohos.resourceschedule.backgroundTaskManager';  
import Want from '@ohos.app.ability.Want';
import AbilityConstant from '@ohos.app.ability.AbilityConstant';
import { BusinessError } from '@ohos.base';

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

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

import { BusinessError } from '@ohos.base';

let request: backgroundTaskManager.EfficiencyResourcesRequest = {
    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 as BusinessError).code} message is ${(error as BusinessError).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.

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

import { BusinessError } from '@ohos.base';

try {
    backgroundTaskManager.resetAllEfficiencyResources();
} catch (error) {
    console.error(`resetAllEfficiencyResources failed. code is ${(error as BusinessError).code} message is ${(error as BusinessError).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.
The maximum duration of a transient task is 3 minutes in normal cases. In the case of a low battery, 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.
System API: This is a system API.
VOIP 8 Audio and video calls.
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.
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.
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.
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_LOCK10+ 128 RUNNING_LOCK resources are not proxied when the application is suspended.
SENSOR10+ 256 Sensor callbacks are not intercepted.

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