# @ohos.request (Upload and Download)

The **request** module provides applications with basic upload, download, and background transmission agent capabilities.

> **NOTE**
>
> The initial APIs of this module are supported since API version 6. Newly added APIs will be marked with a superscript to indicate their earliest API version.


## Modules to Import


```js
import { request } from '@kit.BasicServicesKit';
```

## Constants

**System capability**: SystemCapability.MiscServices.Download

> **NOTE**
>
> **Network type**: set **networkType** in [DownloadConfig](#downloadconfig) to specify the network type for the download service.<br>
>
> **Download error codes**: values of **err** in the callback of [on('fail')<sup>7+</sup>](#onfail7) and the values of the **failedReason** field returned by [getTaskInfo<sup>9+</sup>](#gettaskinfo9).<br>
>
> **Causes of download pause**: values of **pausedReason** returned by [getTaskInfo<sup>9+</sup>](#gettaskinfo9).<br>
>
> **Download task status code**: values of **status** returned by [getTaskInfo<sup>9+</sup>](#gettaskinfo9).

| Name| Type| Value| Description|
| -------- | -------- | -------- | -------- |
| EXCEPTION_PERMISSION<sup>9+</sup> | number |   201   | (Universal error codes) Permission verification failed.|
| EXCEPTION_PARAMCHECK<sup>9+</sup> | number |   401   | (Universal error codes) Parameter check failed.|
| EXCEPTION_UNSUPPORTED<sup>9+</sup> | number |   801   | (Universal error codes) The device does not support this API.|
| EXCEPTION_FILEIO<sup>9+</sup> | number |   13400001   | (Specific error codes) Abnormal file operation.|
| EXCEPTION_FILEPATH<sup>9+</sup> | number |   13400002   | (Specific error codes) Abnormal file path.|
| EXCEPTION_SERVICE<sup>9+</sup> | number |   13400003   | (Specific error codes) Abnormal service.|
| EXCEPTION_OTHERS<sup>9+</sup> | number |   13499999   | (Specific error codes) Other errors.|
| NETWORK_MOBILE<sup>6+</sup> | number | 0x00000001 | (Network type) Bit flag download allowed on a mobile network.|
| NETWORK_WIFI<sup>6+</sup> | number | 0x00010000 | (Network type) Bit flag download allowed on a WLAN.|
| ERROR_CANNOT_RESUME<sup>7+</sup> | number |   0   | (Download error codes) Failure to resume the download due to network errors.|
| ERROR_DEVICE_NOT_FOUND<sup>7+</sup> | number |   1   | (Download error codes) Failure to find a storage device such as a memory card.|
| ERROR_FILE_ALREADY_EXISTS<sup>7+</sup> | number |   2   | (Download error codes) Failure to download the file because it already exists.|
| ERROR_FILE_ERROR<sup>7+</sup> | number |   3   | (Download error codes) File operation failed.|
| ERROR_HTTP_DATA_ERROR<sup>7+</sup> | number |   4   | (Download error codes) HTTP transmission failed.|
| ERROR_INSUFFICIENT_SPACE<sup>7+</sup> | number |   5   | (Download error codes) Insufficient storage space.|
| ERROR_TOO_MANY_REDIRECTS<sup>7+</sup> | number |   6   | (Download error codes) Error caused by too many network redirections.|
| ERROR_UNHANDLED_HTTP_CODE<sup>7+</sup> | number |   7   | (Download error codes) Unidentified HTTP code.|
| ERROR_UNKNOWN<sup>7+</sup> | number |   8   | (Download error codes) Unknown error. (In API version 12 or earlier, only serial connection to the IP addresses associated with the specified domain name is supported, and the connection time for a single IP address is not controllable. If the first IP address returned by the DNS is blocked, a handshake timeout may occur, leading to an **ERROR_UNKNOWN** error.)|
| ERROR_OFFLINE<sup>9+</sup> | number |   9   | (Download error codes) No network connection.|
| ERROR_UNSUPPORTED_NETWORK_TYPE<sup>9+</sup> | number |   10   | (Download error codes) Network type mismatch.|
| PAUSED_QUEUED_FOR_WIFI<sup>7+</sup> | number |   0   | (Causes of download pause) Download paused and queuing for a WLAN connection, because the file size exceeds the maximum value allowed for a mobile network session.|
| PAUSED_WAITING_FOR_NETWORK<sup>7+</sup> | number |   1   | (Causes of download pause) Download paused due to a network connection problem, for example, network disconnection.|
| PAUSED_WAITING_TO_RETRY<sup>7+</sup> | number |   2   | (Causes of download pause) Download paused and then retried.|
| PAUSED_BY_USER<sup>9+</sup> | number |   3   | (Causes of download pause) The user paused the session.|
| PAUSED_UNKNOWN<sup>7+</sup> | number |   4   | (Causes of download pause) Download paused due to unknown reasons.|
| SESSION_SUCCESSFUL<sup>7+</sup> | number |   0   | (Download task status codes) Successful download.|
| SESSION_RUNNING<sup>7+</sup> | number |   1   | (Download task status codes) Download in progress.|
| SESSION_PENDING<sup>7+</sup> | number |   2   | (Download task status codes) Download pending.|
| SESSION_PAUSED<sup>7+</sup> | number |   3   | (Download task status codes) Download paused.|
| SESSION_FAILED<sup>7+</sup> | number |   4   | (Download task status codes) Download failure without retry.|


## request.uploadFile<sup>9+</sup>

uploadFile(context: BaseContext, config: UploadConfig): Promise&lt;UploadTask&gt;

Uploads a file. This API uses a promise to return the result. HTTP is supported. You can use [on('complete'|'fail')<sup>9+</sup>](#oncomplete--fail9) to obtain the upload error information.

**Required permissions**: ohos.permission.INTERNET

**System capability**: SystemCapability.MiscServices.Upload

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| context | [BaseContext](../apis-ability-kit/js-apis-inner-application-baseContext.md) | Yes| Application-based context.|
| config | [UploadConfig](#uploadconfig6) | Yes| Upload configurations.|


**Return value**

| Type| Description|
| -------- | -------- |
| Promise&lt;[UploadTask](#uploadtask)&gt; | Promise used to return the **UploadTask** object.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 201 | the permissions check fails |
| 401 | the parameters check fails.Possible causes: 1. Missing mandatory parameters 2. Incorrect parameter type 3. Parameter verification failed |
| 13400002 | bad file path. |

**Example**

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

  let uploadTask: request.UploadTask;
  let uploadConfig: request.UploadConfig = {
    url: 'http://www.example.com', // Replace the URL with the HTTP address of the real server.
    header: { 'Accept': '*/*' },
    method: "POST",
    files: [{ filename: "test", name: "test", uri: "internal://cache/test.jpg", type: "jpg" }],
    data: [{ name: "name123", value: "123" }],
  };
  try {
    request.uploadFile(getContext(), uploadConfig).then((data: request.UploadTask) => {
      uploadTask = data;
    }).catch((err: BusinessError) => {
      console.error(`Failed to request the upload. Code: ${err.code}, message: ${err.message}`);
    });
  } catch (err) {
    console.error(`Failed to request the upload. err: ${JSON.stringify(err)}`);
  }
  ```

> **NOTE**
>
> For details about how to obtain the context in the example, see [Obtaining the Context of UIAbility](../../application-models/uiability-usage.md#obtaining-the-context-of-uiability).


## request.uploadFile<sup>9+</sup>

uploadFile(context: BaseContext, config: UploadConfig, callback: AsyncCallback&lt;UploadTask&gt;): void

Uploads a file. This API uses an asynchronous callback to return the result. HTTP is supported. You can use [on('complete'|'fail')<sup>9+</sup>](#oncomplete--fail9) to obtain the upload error information.

**Required permissions**: ohos.permission.INTERNET

**System capability**: SystemCapability.MiscServices.Upload

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| context | [BaseContext](../apis-ability-kit/js-apis-inner-application-baseContext.md) | Yes| Application-based context.|
| config | [UploadConfig](#uploadconfig6) | Yes| Upload configurations.|
| callback | AsyncCallback&lt;[UploadTask](#uploadtask)&gt; | Yes| Callback used to return the **UploadTask** object. If the operation is successful, **err** is **undefined**, and **data** is the **UploadTask** object obtained. Otherwise, **err** is an error object.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 201 | the permissions check fails |
| 401 | the parameters check fails.Possible causes: 1. Missing mandatory parameters 2. Incorrect parameter type 3. Parameter verification failed |
| 13400002 | bad file path. |

**Example**

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

  let uploadTask: request.UploadTask;
  let uploadConfig: request.UploadConfig = {
    url: 'http://www.example.com', // Replace the URL with the HTTP address of the real server.
    header: { 'Accept': '*/*' },
    method: "POST",
    files: [{ filename: "test", name: "test", uri: "internal://cache/test.jpg", type: "jpg" }],
    data: [{ name: "name123", value: "123" }],
  };
  try {
    request.uploadFile(getContext(), uploadConfig, (err: BusinessError, data: request.UploadTask) => {
      if (err) {
        console.error(`Failed to request the upload. Code: ${err.code}, message: ${err.message}`);
        return;
      }
      uploadTask = data;
    });
  } catch (err) {
    console.error(`Failed to request the upload. err: ${JSON.stringify(err)}`);
  }
  ```

> **NOTE**
>
> For details about how to obtain the context in the example, see [Obtaining the Context of UIAbility](../../application-models/uiability-usage.md#obtaining-the-context-of-uiability).

## request.upload<sup>(deprecated)</sup>

upload(config: UploadConfig): Promise&lt;UploadTask&gt;

Uploads files. This API uses a promise to return the result.

**Model restriction**: This API can be used only in the FA model.

> **NOTE**
>
> This API is deprecated since API version 9. You are advised to use [request.uploadFile<sup>9+</sup>](#requestuploadfile9) instead.

**Required permissions**: ohos.permission.INTERNET

**System capability**: SystemCapability.MiscServices.Upload

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| config | [UploadConfig](#uploadconfig6) | Yes| Upload configurations.|

**Return value**

| Type| Description|
| -------- | -------- |
| Promise&lt;[UploadTask](#uploadtask)&gt; | Promise used to return the **UploadTask** object.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 201 | the permissions check fails |

**Example**

  ```js
  let uploadTask;
  let uploadConfig = {
    url: 'http://www.example.com', // Replace the URL with the HTTP address of the real server.
    header: { 'Accept': '*/*' },
    method: "POST",
    files: [{ filename: "test", name: "test", uri: "internal://cache/test.jpg", type: "jpg" }],
    data: [{ name: "name123", value: "123" }],
  };
  request.upload(uploadConfig).then((data) => {
    uploadTask = data;
  }).catch((err) => {
    console.error(`Failed to request the upload. Code: ${err.code}, message: ${err.message}`);
  })
  ```


## request.upload<sup>(deprecated)</sup>

upload(config: UploadConfig, callback: AsyncCallback&lt;UploadTask&gt;): void

Uploads files. This API uses an asynchronous callback to return the result.

**Model restriction**: This API can be used only in the FA model.

> **NOTE**
>
> This API is deprecated since API version 9. You are advised to use [request.uploadFile<sup>9+</sup>](#requestuploadfile9-1) instead.

**Required permissions**: ohos.permission.INTERNET

**System capability**: SystemCapability.MiscServices.Upload

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| config | [UploadConfig](#uploadconfig6) | Yes| Upload configurations.|
| callback | AsyncCallback&lt;[UploadTask](#uploadtask)&gt; | Yes| Callback used to return the **UploadTask** object. If the operation is successful, **err** is **undefined**, and **data** is the **UploadTask** object obtained. Otherwise, **err** is an error object.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 201 | the permissions check fails |

**Example**

  ```js
  let uploadTask;
  let uploadConfig = {
    url: 'http://www.example.com', // Replace the URL with the HTTP address of the real server.
    header: { 'Accept': '*/*' },
    method: "POST",
    files: [{ filename: "test", name: "test", uri: "internal://cache/test.jpg", type: "jpg" }],
    data: [{ name: "name123", value: "123" }],
  };
  request.upload(uploadConfig, (err, data) => {
    if (err) {
      console.error(`Failed to request the upload. Code: ${err.code}, message: ${err.message}`);
      return;
    }
    uploadTask = data;
  });
  ```

## UploadTask

Implements file uploads. Before using any APIs of this class, you must obtain an **UploadTask** object through [request.uploadFile<sup>9+</sup>](#requestuploadfile9) in promise mode or [request.uploadFile<sup>9+</sup>](#requestuploadfile9-1) in callback mode.



### on('progress')

on(type: 'progress', callback:(uploadedSize: number, totalSize: number) =&gt; void): void

Subscribes to upload progress events. This API uses an asynchronous callback to return the result.

> **NOTE**
>
> To maintain a balance between power consumption and performance, this API cannot be called when the application is running in the background.

**System capability**: SystemCapability.MiscServices.Upload

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| type | string | Yes| Type of the event to subscribe to. The value is **'progress'** (upload progress).|
| callback | function | Yes| Callback used to return the size of the uploaded file and the total size of the file to upload.|

  Parameters of the callback function

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| uploadedSize | number | Yes| Size of the uploaded files, in bytes.|
| totalSize | number | Yes| Total size of the files to upload, in bytes.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 401 | the parameters check fails.Possible causes: 1. Missing mandatory parameters 2. Incorrect parameter type 3. Parameter verification failed |

**Example**

<!--code_no_check-->
  ```ts
  let upProgressCallback = (uploadedSize: number, totalSize: number) => {
    console.info("upload totalSize:" + totalSize + "  uploadedSize:" + uploadedSize);
  };
  uploadTask.on('progress', upProgressCallback);
  ```


### on('headerReceive')<sup>7+</sup>

on(type: 'headerReceive', callback:  (header: object) =&gt; void): void

Subscribes to HTTP response events for the upload task. This API uses a callback to return the result asynchronously.

**System capability**: SystemCapability.MiscServices.Upload

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| type | string | Yes| Type of the event to subscribe to. The value is **'headerReceive'** (response received).|
| callback | function | Yes| Callback used to return the response content.|

  Parameters of the callback function

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| header | object | Yes| HTTP response.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 401 | the parameters check fails.Possible causes: 1. Missing mandatory parameters 2. Incorrect parameter type 3. Parameter verification failed |

**Example**

<!--code_no_check-->
  ```ts
  let headerCallback = (headers: object) => {
    console.info("upOnHeader headers:" + JSON.stringify(headers));
  };
  uploadTask.on('headerReceive', headerCallback);
  ```


### on('complete' | 'fail')<sup>9+</sup>

 on(type:'complete' | 'fail', callback: Callback&lt;Array&lt;TaskState&gt;&gt;): void;

Subscribes to upload completion or failure events. This API uses an asynchronous callback to return the result.

**System capability**: SystemCapability.MiscServices.Upload

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| type | string | Yes| Callback types for subscribing to the upload events, including **'complete'\|'fail'**.<br>\- **'complete'**: the upload is complete.<br>\- **'fail'**: the upload fails. |
| callback | Callback&lt;Array&lt;[TaskState](#taskstate9)&gt;&gt; | Yes| Callback used to return the result.  |

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 401 | the parameters check fails.Possible causes: 1. Missing mandatory parameters 2. Incorrect parameter type 3. Parameter verification failed |

**Example**

<!--code_no_check-->
  ```ts
  let upCompleteCallback = (taskStates: Array<request.TaskState>) => {
    for (let i = 0; i < taskStates.length; i++) {
      console.info("upOnComplete taskState:" + JSON.stringify(taskStates[i]));
    }
  };
  uploadTask.on('complete', upCompleteCallback);

  let upFailCallback = (taskStates: Array<request.TaskState>) => {
    for (let i = 0; i < taskStates.length; i++) {
      console.info("upOnFail taskState:" + JSON.stringify(taskStates[i]));
    }
  };
  uploadTask.on('fail', upFailCallback);
  ```


### off('progress')

off(type:  'progress',  callback?: (uploadedSize: number, totalSize: number) =&gt;  void): void

Unsubscribes from upload progress events.

**System capability**: SystemCapability.MiscServices.Upload

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| type | string | Yes| Type of the event to unsubscribe from. The value is **'progress'** (upload progress).|
| callback | function | No| Callback to unregister. If this parameter is not specified, all callbacks of the current type will be unregistered.|

Parameters of the callback function

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| uploadedSize | number | Yes| Size of the uploaded files, in bytes.|
| totalSize | number | Yes| Total size of the files to upload, in bytes.|
**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 401 | the parameters check fails.Possible causes: 1. Missing mandatory parameters 2. Incorrect parameter type 3. Parameter verification failed |

**Example**

<!--code_no_check-->
  ```ts
  let upProgressCallback1 = (uploadedSize: number, totalSize: number) => {
    console.info('Upload delete progress notification.' + 'totalSize:' + totalSize + 'uploadedSize:' + uploadedSize);
  };
  let upProgressCallback2 = (uploadedSize: number, totalSize: number) => {
    console.info('Upload delete progress notification.' + 'totalSize:' + totalSize + 'uploadedSize:' + uploadedSize);
  };
  uploadTask.on('progress', upProgressCallback1);
  uploadTask.on('progress', upProgressCallback2);
  // Unsubscribe from upProgressCallback1.
  uploadTask.off('progress', upProgressCallback1);
  // Unsubscribe from all callbacks of upload progress events.
  uploadTask.off('progress');
  ```


### off('headerReceive')<sup>7+</sup>

off(type: 'headerReceive', callback?: (header: object) =&gt; void): void

Unsubscribes from HTTP response events for the upload task.

**System capability**: SystemCapability.MiscServices.Upload

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| type | string | Yes| Type of the event to unsubscribe from. The value is **'headerReceive'** (response received).|
| callback | function | No| Callback to unregister. If this parameter is not specified, all callbacks of the current type will be unregistered.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 401 | the parameters check fails.Possible causes: 1. Missing mandatory parameters 2. Incorrect parameter type 3. Parameter verification failed |

**Example**

<!--code_no_check-->
  ```ts
  let headerCallback1 = (header: object) => {
    console.info(`Upload delete headerReceive notification. header: ${JSON.stringify(header)}`);
  };
  let headerCallback2 = (header: object) => {
    console.info(`Upload delete headerReceive notification. header: ${JSON.stringify(header)}`);
  };
  uploadTask.on('headerReceive', headerCallback1);
  uploadTask.on('headerReceive', headerCallback2);
  // Unsubscribe from headerCallback1.
  uploadTask.off('headerReceive', headerCallback1);
  // Unsubscribe from all callbacks of the HTTP header events for the upload task.
  uploadTask.off('headerReceive');
  ```

### off('complete' | 'fail')<sup>9+</sup>

 off(type:'complete' | 'fail', callback?: Callback&lt;Array&lt;TaskState&gt;&gt;): void;

Unsubscribes from upload completion or failure events.

**System capability**: SystemCapability.MiscServices.Upload

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| type | string | Yes| Type of the event to subscribe to. The value **'complete'** means the upload completion event, and **'fail'** means the upload failure event.|
| callback | Callback&lt;Array&lt;[TaskState](#taskstate9)&gt;&gt; | No| Callback to unregister. If this parameter is not specified, all callbacks of the current type will be unregistered.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 401 | the parameters check fails.Possible causes: 1. Missing mandatory parameters 2. Incorrect parameter type 3. Parameter verification failed |

**Example**

<!--code_no_check-->
  ```ts
  let upCompleteCallback1 = (taskStates: Array<request.TaskState>) => {
    console.info('Upload delete complete notification.');
    for (let i = 0; i < taskStates.length; i++) {
      console.info('taskState:' + JSON.stringify(taskStates[i]));
    }
  };
  let upCompleteCallback2 = (taskStates: Array<request.TaskState>) => {
    console.info('Upload delete complete notification.');
    for (let i = 0; i < taskStates.length; i++) {
      console.info('taskState:' + JSON.stringify(taskStates[i]));
    }
  };
  uploadTask.on('complete', upCompleteCallback1);
  uploadTask.on('complete', upCompleteCallback2);
  // Unsubscribe from headerCallback1.
  uploadTask.off('complete', upCompleteCallback1);
  // Unsubscribe from all callbacks of the upload completion events.
  uploadTask.off('complete');

  let upFailCallback1 = (taskStates: Array<request.TaskState>) => {
    console.info('Upload delete fail notification.');
    for (let i = 0; i < taskStates.length; i++) {
      console.info('taskState:' + JSON.stringify(taskStates[i]));
    }
  };
  let upFailCallback2 = (taskStates: Array<request.TaskState>) => {
    console.info('Upload delete fail notification.');
    for (let i = 0; i < taskStates.length; i++) {
      console.info('taskState:' + JSON.stringify(taskStates[i]));
    }
  };
  uploadTask.on('fail', upFailCallback1);
  uploadTask.on('fail', upFailCallback2);
  // Unsubscribe from headerCallback1.
  uploadTask.off('fail', upFailCallback1);
  // Unsubscribe from all callbacks of the upload failure events.
  uploadTask.off('fail');
  ```

### delete<sup>9+</sup>
delete(): Promise&lt;boolean&gt;

Deletes this upload task. This API uses a promise to return the result.

**Required permissions**: ohos.permission.INTERNET

**System capability**: SystemCapability.MiscServices.Upload

**Return value**

| Type| Description|
| -------- | -------- |
| Promise&lt;boolean&gt; | Promise used to return the result. The value **true** indicates that the operation is successful, and the value **false** indicates the opposite.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 201 | the permissions check fails |

**Example**

<!--code_no_check-->
  ```ts
  uploadTask.delete().then((result: boolean) => {
    console.info('Succeeded in deleting the upload task.');
  }).catch((err: BusinessError) => {
    console.error(`Failed to delete the upload task. Code: ${err.code}, message: ${err.message}`);
  });
  ```

> **NOTE**
>
> The scenarios for triggering error code 401 do not actually exist. Therefore, `401 the parameters check fails` is removed from API version 12.


### delete<sup>9+</sup>

delete(callback: AsyncCallback&lt;boolean&gt;): void

Deletes this upload task. This API uses an asynchronous callback to return the result.

**Required permissions**: ohos.permission.INTERNET

**System capability**: SystemCapability.MiscServices.Upload

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| callback | AsyncCallback&lt;boolean&gt; | Yes| Callback used to return the result. The value **true** indicates that the operation is successful, and the value **false** indicates the opposite.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 201 | the permissions check fails |

**Example**

<!--code_no_check-->
  ```ts
  uploadTask.delete((err: BusinessError, result: boolean) => {
    if (err) {
      console.error(`Failed to delete the upload task. Code: ${err.code}, message: ${err.message}`);
      return;
    }
    console.info('Succeeded in deleting the upload task.');
  });
  ```

> **NOTE**
>
> The scenarios for triggering error code 401 do not actually exist. Therefore, `401 the parameters check fails` is removed from API version 12.


### remove<sup>(deprecated)</sup>

remove(): Promise&lt;boolean&gt;

Removes this upload task. This API uses a promise to return the result.

> **NOTE**
>
> This API is deprecated since API version 9. You are advised to use [delete<sup>9+</sup>](#delete9) instead.

**Required permissions**: ohos.permission.INTERNET

**System capability**: SystemCapability.MiscServices.Upload

**Return value**

| Type| Description|
| -------- | -------- |
| Promise&lt;boolean&gt; | Promise used to return the result. The value **true** indicates that the operation is successful, and the value **false** indicates the opposite.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 201 | the permissions check fails |

**Example**

  ```js
  uploadTask.remove().then((result) => {
    console.info('Succeeded in removing the upload task.');
  }).catch((err) => {
    console.error(`Failed to remove the upload task. Code: ${err.code}, message: ${err.message}`);
  });
  ```


### remove<sup>(deprecated)</sup>

remove(callback: AsyncCallback&lt;boolean&gt;): void

Removes this upload task. This API uses an asynchronous callback to return the result.

> **NOTE**
>
> This API is deprecated since API version 9. You are advised to use [delete<sup>9+</sup>](#delete9-1) instead.

**Required permissions**: ohos.permission.INTERNET

**System capability**: SystemCapability.MiscServices.Upload

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| callback | AsyncCallback&lt;boolean&gt; | Yes| Callback used to return the result. The value **true** indicates that the operation is successful, and the value **false** indicates the opposite.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 201 | the permissions check fails |

**Example**

  ```js
  uploadTask.remove((err, result) => {
    if (err) {
      console.error(`Failed to remove the upload task. Code: ${err.code}, message: ${err.message}`);
      return;
    }
    if (result) {
      console.info('Succeeded in removing the upload task.');
    } else {
      console.error(`Failed to remove the upload task. Code: ${err.code}, message: ${err.message}`);
    }
  });
  ```

## UploadConfig<sup>6+</sup>
Describes the configuration of an upload task.

**System capability**: SystemCapability.MiscServices.Upload

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| url | string | Yes| Resource URL. The value contains a maximum of 2048 characters.|
| header | Object | Yes| HTTP or HTTPS header added to an upload request.|
| method | string | Yes|  HTTP request method. The value can be **POST** or **PUT**. The default value is **POST**. Use the **PUT** method to modify resources and the **POST** method to add resources.|
| index<sup>11+</sup> | number | No| Path index of the task. The default value is **0**.|
| begins<sup>11+</sup> | number | No| File start point to read when the task begins. The default value is **0**. The value is a closed interval.|
| ends<sup>11+</sup> | number | No| File start point to read when the task ends. The default value is **-1**. The value is a closed interval.|
| files | Array&lt;[File](#file)&gt; | Yes| List of files to upload. The files are submitted in multipart/form-data format.|
| data | Array&lt;[RequestData](#requestdata)&gt; | Yes| Form data in the request body.|

## TaskState<sup>9+</sup>
Implements a **TaskState** object, which is the callback parameter of the [on('complete' | 'fail')<sup>9+</sup>](#oncomplete--fail9) and [off('complete' | 'fail')<sup>9+</sup>](#offcomplete--fail9) APIs.

**System capability**: SystemCapability.MiscServices.Upload

| Name| Type| Mandatory| Description                                                                                                                                       |
| -------- | -------- | -------- |-------------------------------------------------------------------------------------------------------------------------------------------|
| path | string | Yes| File path.                                                                                                                                     |
| responseCode | number | Yes| Return value of an upload task. The value **0** means that the task is successful, and other values means that the task fails. For details about the task result, see **message**. You are advised to create an upload task by using [request.agent.create<sup>10+</sup>](#requestagentcreate10-1) and handle exceptions based on standard error codes.|
| message | string | Yes| Description of the upload task result.                                                                                                                               |

The following table describes the enum values of **responseCode**.

| Result Code| Description                              |
|-----|------------------------------------|
| 0   | Upload success.                              |
| 5   | Task suspended or stopped proactively.                        |
| 6   | Foreground task stopped. The reason is that the application, to which the task belongs, is switched to the background or terminated. Check the application status. |
| 7   | No network connection. Check whether the device is connected to the network.                 |
| 8   | Network mismatch. Check whether the current network type matches the network type required by the task.    |
| 10  | Failed to create the HTTP request. Verify the parameters or try again.         |
| 12  | Request timeout. Verify the parameter configuration or the network connection, or try again.         |
| 13  | Connection failed. Verify the parameter configuration or the network connection, or try again.       |
| 14  | Request failed. Verify the parameter configuration or the network connection, or try again.       |
| 15  | Upload failed. Verify the parameter configuration or the network connection, or try again.       |
| 16  | Redirection failed. Verify the parameter configuration or the network connection, or try again.      |
| 17  | Protocol error. The server returns a 4XX or 5XX status code. Verify the parameter configuration and try again.|
| 20  | Other errors. Verify the parameter configuration or the network connection, or try again.       |

## File
Defines the file list in [UploadConfig<sup>6+</sup>](#uploadconfig6).

**System capability**: SystemCapability.MiscServices.Download

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| filename | string | Yes| File name in the header when **multipart** is used.|
| name | string | Yes| Name of a form item when **multipart** is used. The default value is **file**.|
| uri | string | Yes| Local path for storing files.<br>Only internal protocols are supported in the path. Therefore, **internal://cache/**, that is, **context.cacheDir** of the caller (namely, cache directory of the input **context**), must be included in the path,<br>for example, **internal://cache/path/to/file.txt**.|
| type | string | Yes| Type of the file content. By default, the type is obtained based on the extension of the file name or URI.|


## RequestData
Defines the form data in [UploadConfig<sup>6+</sup>](#uploadconfig6).

**System capability**: SystemCapability.MiscServices.Download

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| name | string | Yes| Name of a form element.|
| value | string | Yes| Value of a form element.|

## request.downloadFile<sup>9+</sup>

downloadFile(context: BaseContext, config: DownloadConfig): Promise&lt;DownloadTask&gt;

Downloads a file. This API uses a promise to return the result. HTTP is supported. You can use [on('complete'|'pause'|'remove')<sup>7+</sup>](#oncompletepauseremove7) to obtain the download task state, which can be completed, paused, or removed. You can also use [on('fail')<sup>7+</sup>](#onfail7) to obtain the task download error information.

**Required permissions**: ohos.permission.INTERNET

**System capability**: SystemCapability.MiscServices.Download

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| context | [BaseContext](../apis-ability-kit/js-apis-inner-application-baseContext.md) | Yes| Application-based context.|
| config | [DownloadConfig](#downloadconfig) | Yes| Download configuration.|

**Return value**

| Type| Description|
| -------- | -------- |
| Promise&lt;[DownloadTask](#downloadtask)&gt; | Promise used to return the **DownloadTask** object.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 201 | the permissions check fails |
| 401 | the parameters check fails.Possible causes: 1. Missing mandatory parameters 2. Incorrect parameter type 3. Parameter verification failed |
| 13400001 | file operation error. |
| 13400002 | bad file path. |
| 13400003 | task service ability error. |

**Example**

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

  try {
    // Replace the URL with the HTTP address of the real server.
    request.downloadFile(getContext(), { url: 'https://xxxx/xxxx.hap' }).then((data: request.DownloadTask) => {
       let downloadTask: request.DownloadTask = data;
    }).catch((err: BusinessError) => {
      console.error(`Failed to request the download. Code: ${err.code}, message: ${err.message}`);
    })
  } catch (err) {
    console.error(`Failed to request the download. err: ${JSON.stringify(err)}`);
  }
  ```

> **NOTE**
>
> For details about how to obtain the context in the example, see [Obtaining the Context of UIAbility](../../application-models/uiability-usage.md#obtaining-the-context-of-uiability).


## request.downloadFile<sup>9+</sup>

downloadFile(context: BaseContext, config: DownloadConfig, callback: AsyncCallback&lt;DownloadTask&gt;): void;

Downloads a file. This API uses an asynchronous callback to return the result. HTTP is supported. You can use [on('complete'|'pause'|'remove')<sup>7+</sup>](#oncompletepauseremove7) to obtain the download task state, which can be completed, paused, or removed. You can also use [on('fail')<sup>7+</sup>](#onfail7) to obtain the task download error information.

**Required permissions**: ohos.permission.INTERNET

**System capability**: SystemCapability.MiscServices.Download

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| context | [BaseContext](../apis-ability-kit/js-apis-inner-application-baseContext.md) | Yes| Application-based context.|
| config | [DownloadConfig](#downloadconfig) | Yes| Download configuration.|
| callback | AsyncCallback&lt;[DownloadTask](#downloadtask)&gt; | Yes| Callback used to return the result. If the operation is successful, **err** is **undefined** and **data** is the **DownloadTask** object obtained. Otherwise, **err** is an error object.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 201 | the permissions check fails |
| 401 | the parameters check fails.Possible causes: 1. Missing mandatory parameters 2. Incorrect parameter type 3. Parameter verification failed |
| 13400001 | file operation error. |
| 13400002 | bad file path. |
| 13400003 | task service ability error. |

**Example**

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

  try {
    // Replace the URL with the HTTP address of the real server.
    request.downloadFile(getContext(), {
      url: 'https://xxxx/xxxxx.hap',
      filePath: 'xxx/xxxxx.hap'
    }, (err: BusinessError, data: request.DownloadTask) => {
      if (err) {
        console.error(`Failed to request the download. Code: ${err.code}, message: ${err.message}`);
        return;
      }
      let downloadTask: request.DownloadTask = data;
    });
  } catch (err) {
    console.error(`Failed to request the download. err: ${JSON.stringify(err)}`);
  }
  ```

> **NOTE**
>
> For details about how to obtain the context in the example, see [Obtaining the Context of UIAbility](../../application-models/uiability-usage.md#obtaining-the-context-of-uiability).

## request.download<sup>(deprecated)</sup>

download(config: DownloadConfig): Promise&lt;DownloadTask&gt;

Downloads files. This API uses a promise to return the result.

> **NOTE**
>
> This API is deprecated since API version 9. You are advised to use [request.downloadFile<sup>9+</sup>](#requestdownloadfile9) instead.

**Model restriction**: This API can be used only in the FA model.

**Required permissions**: ohos.permission.INTERNET

**System capability**: SystemCapability.MiscServices.Download

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| config | [DownloadConfig](#downloadconfig) | Yes| Download configuration.|

**Return value**

| Type| Description|
| -------- | -------- |
| Promise&lt;[DownloadTask](#downloadtask)&gt; | Promise used to return the **DownloadTask** object.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 201 | the permissions check fails |

**Example**

  ```js
  let downloadTask;
  // Replace the URL with the HTTP address of the real server.
  request.download({ url: 'https://xxxx/xxxx.hap' }).then((data) => {
    downloadTask = data;
  }).catch((err) => {
    console.error(`Failed to request the download. Code: ${err.code}, message: ${err.message}`);
  })
  ```


## request.download<sup>(deprecated)</sup>

download(config: DownloadConfig, callback: AsyncCallback&lt;DownloadTask&gt;): void

Downloads files. This API uses an asynchronous callback to return the result.

> **NOTE**
>
> This API is deprecated since API version 9. You are advised to use [request.downloadFile<sup>9+</sup>](#requestdownloadfile9-1) instead.

**Model restriction**: This API can be used only in the FA model.

**Required permissions**: ohos.permission.INTERNET

**System capability**: SystemCapability.MiscServices.Download

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| config | [DownloadConfig](#downloadconfig) | Yes| Download configuration.|
| callback | AsyncCallback&lt;[DownloadTask](#downloadtask)&gt; | Yes| Callback used to return the result. If the operation is successful, **err** is **undefined** and **data** is the **DownloadTask** object obtained. Otherwise, **err** is an error object.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 201 | the permissions check fails |

**Example**

  ```js
  let downloadTask;
  // Replace the URL with the HTTP address of the real server.
  request.download({ url: 'https://xxxx/xxxxx.hap', 
  filePath: 'xxx/xxxxx.hap'}, (err, data) => {
    if (err) {
      console.error(`Failed to request the download. Code: ${err.code}, message: ${err.message}`);
      return;
    }
    downloadTask = data;
  });
  ```

## DownloadTask

Implements file downloads. Before using any APIs of this class, you must obtain a **DownloadTask** object through [request.downloadFile<sup>9+</sup>](#requestdownloadfile9) in promise mode or [request.downloadFile<sup>9+</sup>](#requestdownloadfile9-1) in callback mode.


### on('progress')

on(type: 'progress', callback:(receivedSize: number, totalSize: number) =&gt; void): void

Subscribes to download progress events. This API uses an asynchronous callback to return the result.

> **NOTE**
>
> To maintain a balance between power consumption and performance, this API cannot be called when the application is running in the background.

**System capability**: SystemCapability.MiscServices.Download

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| type | string | Yes| Type of the event to subscribe to. The value is **'progress'** (download progress).|
| callback | function | Yes| Callback used to return the size of the uploaded file and the total size of the file to download.|

  Parameters of the callback function

| Name| Type| Mandatory| Description                                                                     |
| -------- | -------- | -------- |-------------------------------------------------------------------------|
| receivedSize | number | Yes| Current download progress, in bytes.                                                          |
| totalSize | number | Yes| Total size of the files to download, in bytes. If the server uses the chunk mode for data transmission and the total file size cannot be obtained from the request header, the value of **totalSize** is treated as **-1**.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 401 | the parameters check fails.Possible causes: 1. Missing mandatory parameters 2. Incorrect parameter type 3. Parameter verification failed |

**Example**

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

  try {
    // Replace the URL with the HTTP address of the real server.
    request.downloadFile(getContext(), { url: 'https://xxxx/xxxx.hap' }).then((data: request.DownloadTask) => {
      let downloadTask: request.DownloadTask = data;
      let progressCallback = (receivedSize: number, totalSize: number) => {
        console.info("download receivedSize:" + receivedSize + " totalSize:" + totalSize);
      };
      downloadTask.on('progress', progressCallback);
    }).catch((err: BusinessError) => {
      console.error(`Failed to request the download. Code: ${err.code}, message: ${err.message}`);
    })
  } catch (err) {
    console.error(`Failed to request the download. err: ${JSON.stringify(err)}`);
  }
  ```


### off('progress')

off(type: 'progress', callback?: (receivedSize: number, totalSize: number) =&gt; void): void

Unsubscribes from download progress events.

**System capability**: SystemCapability.MiscServices.Download

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| type | string | Yes| Type of the event to unsubscribe from. The value is **'progress'** (download progress).|
| callback | function | No| Callback to unregister. If this parameter is not specified, all callbacks of the current type will be unregistered.|

  Parameters of the callback function

| Name| Type| Mandatory| Description                                                                     |
| -------- | -------- | -------- |-------------------------------------------------------------------------|
| receivedSize | number | Yes| Current download progress, in bytes.                                                          |
| totalSize | number | Yes| Total size of the files to download, in bytes. If the server uses the chunk mode for data transmission and the total file size cannot be obtained from the request header, the value of **totalSize** is treated as **-1**.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 401 | the parameters check fails.Possible causes: 1. Missing mandatory parameters 2. Incorrect parameter type 3. Parameter verification failed |

**Example**

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

try {
  // Replace the URL with the HTTP address of the real server.
  request.downloadFile(getContext(), { url: 'https://xxxx/xxxx.hap' }).then((data: request.DownloadTask) => {
    let downloadTask: request.DownloadTask = data;
    let progressCallback1 = (receivedSize: number, totalSize: number) => {
      console.info('Download delete progress notification.' + 'receivedSize:' + receivedSize + 'totalSize:' + totalSize);
    };
    let progressCallback2 = (receivedSize: number, totalSize: number) => {
      console.info('Download delete progress notification.' + 'receivedSize:' + receivedSize + 'totalSize:' + totalSize);
    };
    downloadTask.on('progress', progressCallback1);
    downloadTask.on('progress', progressCallback2);
    // Unsubscribe from progressCallback1.
    downloadTask.off('progress', progressCallback1);
    // Unsubscribe from all callbacks of download progress events.
    downloadTask.off('progress');
  }).catch((err: BusinessError) => {
    console.error(`Failed to request the download. Code: ${err.code}, message: ${err.message}`);
  })
} catch (err) {
  console.error(`Failed to request the download. err: ${JSON.stringify(err)}`);
}
  ```


### on('complete'|'pause'|'remove')<sup>7+</sup>

on(type: 'complete'|'pause'|'remove', callback:() =&gt; void): void

Subscribes to download events. This API uses a callback to return the result asynchronously.

**System capability**: SystemCapability.MiscServices.Download

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| type | string | Yes| Type of the event to subscribe to.<br>- **'complete'**: download task completion event.<br>- **'pause'**: download task pause event.<br>- **'remove'**: download task removal event.|
| callback | function | Yes| Callback used to return the result.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 401 | the parameters check fails.Possible causes: 1. Missing mandatory parameters 2. Incorrect parameter type 3. Parameter verification failed |

**Example**

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

try {
  // Replace the URL with the HTTP address of the real server.
  request.downloadFile(getContext(), { url: 'https://xxxx/xxxx.hap' }).then((data: request.DownloadTask) => {
    let downloadTask: request.DownloadTask = data;
    let completeCallback = () => {
      console.info('Download task completed.');
    };
    downloadTask.on('complete', completeCallback);

    let pauseCallback = () => {
      console.info('Download task pause.');
    };
    downloadTask.on('pause', pauseCallback);

    let removeCallback = () => {
      console.info('Download task remove.');
    };
    downloadTask.on('remove', removeCallback);
  }).catch((err: BusinessError) => {
    console.error(`Failed to request the download. Code: ${err.code}, message: ${err.message}`);
  })
} catch (err) {
  console.error(`Failed to request the download. err: ${JSON.stringify(err)}`);
}
  ```


### off('complete'|'pause'|'remove')<sup>7+</sup>

off(type: 'complete'|'pause'|'remove', callback?: () =&gt; void): void

Unsubscribes from download events.

**System capability**: SystemCapability.MiscServices.Download

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| type | string | Yes| Type of the event to unsubscribe from.<br>- **'complete'**: download task completion event.<br>- **'pause'**: download task pause event.<br>- **'remove'**: download task removal event.|
| callback | function | No| Callback to unregister. If this parameter is not specified, all callbacks of the current type will be unregistered.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 401 | the parameters check fails.Possible causes: 1. Missing mandatory parameters 2. Incorrect parameter type 3. Parameter verification failed |

**Example**

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

try {
  // Replace the URL with the HTTP address of the real server.
  request.downloadFile(getContext(), { url: 'https://xxxx/xxxx.hap' }).then((data: request.DownloadTask) => {
    let downloadTask: request.DownloadTask = data;
    let completeCallback1 = () => {
      console.info('Download delete complete notification.');
    };
    let completeCallback2 = () => {
      console.info('Download delete complete notification.');
    };
    downloadTask.on('complete', completeCallback1);
    downloadTask.on('complete', completeCallback2);
    // Unsubscribe from completeCallback1.
    downloadTask.off('complete', completeCallback1);
    // Unsubscribe from all callbacks of the download completion events.
    downloadTask.off('complete');

    let pauseCallback1 = () => {
      console.info('Download delete pause notification.');
    };
    let pauseCallback2 = () => {
      console.info('Download delete pause notification.');
    };
    downloadTask.on('pause', pauseCallback1);
    downloadTask.on('pause', pauseCallback2);
    // Unsubscribe from pauseCallback1.
    downloadTask.off('pause', pauseCallback1);
    // Unsubscribe from all callbacks of the download pause events.
    downloadTask.off('pause');

    let removeCallback1 = () => {
      console.info('Download delete remove notification.');
    };
    let removeCallback2 = () => {
      console.info('Download delete remove notification.');
    };
    downloadTask.on('remove', removeCallback1);
    downloadTask.on('remove', removeCallback2);
    // Unsubscribe from removeCallback1.
    downloadTask.off('remove', removeCallback1);
    // Unsubscribe from all callbacks of the download removal events.
    downloadTask.off('remove');
  }).catch((err: BusinessError) => {
    console.error(`Failed to request the download. Code: ${err.code}, message: ${err.message}`);
  })
} catch (err) {
  console.error(`Failed to request the download. err: ${JSON.stringify(err)}`);
}
  
  ```


### on('fail')<sup>7+</sup>

on(type: 'fail', callback: (err: number) =&gt; void): void

Subscribes to download failure events. This API uses an asynchronous callback to return the result.

**System capability**: SystemCapability.MiscServices.Download

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| type | string | Yes| Type of the event to subscribe to. The value is **'fail'** (download failure).|
| callback | function | Yes| Callback for the download task failure event.|

  Parameters of the callback function

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| err | number | Yes| Error code of the download failure. For details about the error codes, see [Download Error Codes](#constants).|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 401 | the parameters check fails.Possible causes: 1. Missing mandatory parameters 2. Incorrect parameter type 3. Parameter verification failed |

**Example**

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

try {
  // Replace the URL with the HTTP address of the real server.
  request.downloadFile(getContext(), { url: 'https://xxxx/xxxx.hap' }).then((data: request.DownloadTask) => {
    let downloadTask: request.DownloadTask = data;
    let failCallback = (err: number) => {
      console.error(`Failed to download the task. Code: ${err}`);
    };
    downloadTask.on('fail', failCallback);
  }).catch((err: BusinessError) => {
    console.error(`Failed to request the download. Code: ${err.code}, message: ${err.message}`);
  })
} catch (err) {
  console.error(`Failed to request the download. err: ${JSON.stringify(err)}`);
}
  ```


### off('fail')<sup>7+</sup>

off(type: 'fail', callback?: (err: number) =&gt; void): void

Unsubscribes from download failure events.

**System capability**: SystemCapability.MiscServices.Download

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| type | string | Yes| Type of the event to unsubscribe from. The value is **'fail'** (download failure).|
| callback | function | No| Callback to unregister. If this parameter is not specified, all callbacks of the current type will be unregistered.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 401 | the parameters check fails.Possible causes: 1. Missing mandatory parameters 2. Incorrect parameter type 3. Parameter verification failed |

**Example**

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

try {
  // Replace the URL with the HTTP address of the real server.
  request.downloadFile(getContext(), { url: 'https://xxxx/xxxx.hap' }).then((data: request.DownloadTask) => {
    let downloadTask: request.DownloadTask = data;
    let failCallback1 = (err: number) => {
      console.error(`Failed to download the task. Code: ${err}`);
    };
    let failCallback2 = (err: number) => {
      console.error(`Failed to download the task. Code: ${err}`);
    };
    downloadTask.on('fail', failCallback1);
    downloadTask.on('fail', failCallback2);
    // Unsubscribe from failCallback1.
    downloadTask.off('fail', failCallback1);
    // Unsubscribe from all callbacks of the download failure events.
    downloadTask.off('fail');
  }).catch((err: BusinessError) => {
    console.error(`Failed to request the download. Code: ${err.code}, message: ${err.message}`);
  })
} catch (err) {
  console.error(`Failed to request the download. err: ${JSON.stringify(err)}`);
}
  ```

### delete<sup>9+</sup>

delete(): Promise&lt;boolean&gt;

Deletes this download task. This API uses a promise to return the result.

**Required permissions**: ohos.permission.INTERNET

**System capability**: SystemCapability.MiscServices.Download

**Return value**

| Type| Description|
| -------- | -------- |
| Promise&lt;boolean&gt; | Promise used to return the result. The value **true** indicates that the operation is successful, and the value **false** indicates the opposite.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 201 | the permissions check fails |

**Example**

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

try {
  // Replace the URL with the HTTP address of the real server.
  request.downloadFile(getContext(), { url: 'https://xxxx/xxxx.hap' }).then((data: request.DownloadTask) => {
    let downloadTask: request.DownloadTask = data;
    downloadTask.delete().then((result: boolean) => {
      console.info('Succeeded in removing the download task.');
    }).catch((err: BusinessError) => {
      console.error(`Failed to remove the download task. Code: ${err.code}, message: ${err.message}`);
    });
  }).catch((err: BusinessError) => {
    console.error(`Failed to request the download. Code: ${err.code}, message: ${err.message}`);
  })
} catch (err) {
  console.error(`Failed to request the download. err: ${JSON.stringify(err)}`);
}
  ```

> **NOTE**
>
> The scenarios for triggering error code 401 do not actually exist. Therefore, `401 the parameters check fails` is removed from API version 12.


### delete<sup>9+</sup>

delete(callback: AsyncCallback&lt;boolean&gt;): void

Deletes this download task. This API uses an asynchronous callback to return the result.

**Required permissions**: ohos.permission.INTERNET

**System capability**: SystemCapability.MiscServices.Download

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| callback | AsyncCallback&lt;boolean&gt; | Yes| Callback used to return the result. The value **true** indicates that the operation is successful, and the value **false** indicates the opposite.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 201 | the permissions check fails |

**Example**

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

try {
  // Replace the URL with the HTTP address of the real server.
  request.downloadFile(getContext(), { url: 'https://xxxx/xxxx.hap' }).then((data: request.DownloadTask) => {
    let downloadTask: request.DownloadTask = data;
    downloadTask.delete((err: BusinessError, result: boolean) => {
      if (err) {
        console.error(`Failed to remove the download task. Code: ${err.code}, message: ${err.message}`);
        return;
      }
      console.info('Succeeded in removing the download task.');
    });
  }).catch((err: BusinessError) => {
    console.error(`Failed to request the download. Code: ${err.code}, message: ${err.message}`);
  })
} catch (err) {
  console.error(`Failed to request the download. err: ${JSON.stringify(err)}`);
}
  ```

> **NOTE**
>
> The scenarios for triggering error code 401 do not actually exist. Therefore, `401 the parameters check fails` is removed from API version 12.


### getTaskInfo<sup>9+</sup>

getTaskInfo(): Promise&lt;DownloadInfo&gt;

Obtains the information about this download task. This API uses a promise to return the result.

**Required permissions**: ohos.permission.INTERNET

**System capability**: SystemCapability.MiscServices.Download

**Return value**

| Type| Description|
| -------- | -------- |
| Promise&lt;[DownloadInfo](#downloadinfo7)&gt; |  Promise used to return the **DownloadInfo** object.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 201 | the permissions check fails |

**Example**

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

try {
  // Replace the URL with the HTTP address of the real server.
  request.downloadFile(getContext(), { url: 'https://xxxx/xxxx.hap' }).then((data: request.DownloadTask) => {
    let downloadTask: request.DownloadTask = data;
    downloadTask.getTaskInfo().then((downloadInfo: request.DownloadInfo) => {
      console.info('Succeeded in querying the download task')
    }).catch((err: BusinessError) => {
      console.error(`Failed to query the download task. Code: ${err.code}, message: ${err.message}`)
    });
  }).catch((err: BusinessError) => {
    console.error(`Failed to request the download. Code: ${err.code}, message: ${err.message}`);
  })
} catch (err) {
  console.error(`Failed to request the download. err: ${JSON.stringify(err)}`);
} 
  ```

> **NOTE**
>
> The scenarios for triggering error code 401 do not actually exist. Therefore, `401 the parameters check fails` is removed from API version 12.


### getTaskInfo<sup>9+</sup>

getTaskInfo(callback: AsyncCallback&lt;DownloadInfo&gt;): void

Obtains this download task. This API uses an asynchronous callback to return the result.

**Required permissions**: ohos.permission.INTERNET

**System capability**: SystemCapability.MiscServices.Download

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| callback | AsyncCallback&lt;[DownloadInfo](#downloadinfo7)&gt; | Yes| Callback used to return the result. If the operation is successful, **err** is **undefined** and **data** is the **DownloadInfo** object obtained. Otherwise, **err** is an error object.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 201 | the permissions check fails |

**Example**

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

try {
  // Replace the URL with the HTTP address of the real server.
  request.downloadFile(getContext(), { url: 'https://xxxx/xxxx.hap' }).then((data: request.DownloadTask) => {
    let downloadTask: request.DownloadTask = data;
    downloadTask.getTaskInfo((err: BusinessError, downloadInfo: request.DownloadInfo) => {
      if (err) {
        console.error(`Failed to query the download mimeType. Code: ${err.code}, message: ${err.message}`);
      } else {
        console.info('Succeeded in querying the download mimeType');
      }
    });
  }).catch((err: BusinessError) => {
    console.error(`Failed to request the download. Code: ${err.code}, message: ${err.message}`);
  })
} catch (err) {
  console.error(`Failed to request the download. err: ${JSON.stringify(err)}`);
}
  ```

> **NOTE**
>
> The scenarios for triggering error code 401 do not actually exist. Therefore, `401 the parameters check fails` is removed from API version 12.


### getTaskMimeType<sup>9+</sup>

getTaskMimeType(): Promise&lt;string&gt;

Obtains **MimeType** (that is, media type of resources) of a download task. This API uses a promise to return the result.

**Required permissions**: ohos.permission.INTERNET

**System capability**: SystemCapability.MiscServices.Download

**Return value**

| Type| Description|
| -------- | -------- |
| Promise&lt;string&gt; | Promise used to return the **MimeType** object.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 201 | the permissions check fails |

**Example**

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

try {
  // Replace the URL with the HTTP address of the real server.
  request.downloadFile(getContext(), { url: 'https://xxxx/xxxx.hap' }).then((data: request.DownloadTask) => {
    let downloadTask: request.DownloadTask = data;
    downloadTask.getTaskMimeType().then((data: string) => {
      console.info('Succeeded in querying the download MimeType');
    }).catch((err: BusinessError) => {
      console.error(`Failed to query the download MimeType. Code: ${err.code}, message: ${err.message}`)
    });
  }).catch((err: BusinessError) => {
    console.error(`Failed to request the download. Code: ${err.code}, message: ${err.message}`);
  })
} catch (err) {
  console.error(`Failed to request the download. err: ${JSON.stringify(err)}`);
}
  ```

> **NOTE**
>
> The scenarios for triggering error code 401 do not actually exist. Therefore, `401 the parameters check fails` is removed from API version 12.


### getTaskMimeType<sup>9+</sup>

getTaskMimeType(callback: AsyncCallback&lt;string&gt;): void;

Obtains the **MimeType** of this download task. This API uses an asynchronous callback to return the result.

**Required permissions**: ohos.permission.INTERNET

**System capability**: SystemCapability.MiscServices.Download

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| callback | AsyncCallback&lt;string&gt; | Yes| Callback used to return the result. If the operation is successful, **err** is **undefined** and data is the **MimeType** object obtained. Otherwise, **err** is an error object.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 201 | the permissions check fails |

**Example**

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

try {
  // Replace the URL with the HTTP address of the real server.
  request.downloadFile(getContext(), { url: 'https://xxxx/xxxx.hap' }).then((data: request.DownloadTask) => {
    let downloadTask: request.DownloadTask = data;
    downloadTask.getTaskMimeType((err: BusinessError, data: string) => {
      if (err) {
        console.error(`Failed to query the download mimeType. Code: ${err.code}, message: ${err.message}`);
      } else {
        console.info('Succeeded in querying the download mimeType');
      }
    });
  }).catch((err: BusinessError) => {
    console.error(`Failed to request the download. Code: ${err.code}, message: ${err.message}`);
  })
} catch (err) {
  console.error(`Failed to request the download. err: ${JSON.stringify(err)}`);
}
  ```

> **NOTE**
>
> The scenarios for triggering error code 401 do not actually exist. Therefore, `401 the parameters check fails` is removed from API version 12.


### suspend<sup>9+</sup>

suspend(): Promise&lt;boolean&gt;

Suspends this download task. This API uses a promise to return the result.

**Required permissions**: ohos.permission.INTERNET

**System capability**: SystemCapability.MiscServices.Download

**Return value**

| Type| Description|
| -------- | -------- |
| Promise&lt;boolean&gt; | Promise used to return the result. The value **true** indicates that the operation is successful, and the value **false** indicates the opposite.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 201 | the permissions check fails |

**Example**

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

try {
  // Replace the URL with the HTTP address of the real server.
  request.downloadFile(getContext(), { url: 'https://xxxx/xxxx.hap' }).then((data: request.DownloadTask) => {
    let downloadTask: request.DownloadTask = data;
    downloadTask.suspend().then((result: boolean) => {
      console.info('Succeeded in pausing the download task.');
    }).catch((err: BusinessError) => {
      console.error(`Failed to pause the download task. Code: ${err.code}, message: ${err.message}`);
    });
  }).catch((err: BusinessError) => {
    console.error(`Failed to request the download. Code: ${err.code}, message: ${err.message}`);
  })
} catch (err) {
  console.error(`Failed to request the download. err: ${JSON.stringify(err)}`);
}
  ```

> **NOTE**
>
> The scenarios for triggering error code 401 do not actually exist. Therefore, `401 the parameters check fails` is removed from API version 12.


### suspend<sup>9+</sup>

suspend(callback: AsyncCallback&lt;boolean&gt;): void

Suspends this download task. This API uses an asynchronous callback to return the result.

**Required permissions**: ohos.permission.INTERNET

**System capability**: SystemCapability.MiscServices.Download

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| callback | AsyncCallback&lt;boolean&gt; | Yes| Callback used to return the result. The value **true** indicates that the operation is successful, and the value **false** indicates the opposite.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 201 | the permissions check fails |

**Example**

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

try {
  // Replace the URL with the HTTP address of the real server.
  request.downloadFile(getContext(), { url: 'https://xxxx/xxxx.hap' }).then((data: request.DownloadTask) => {
    let downloadTask: request.DownloadTask = data;
    downloadTask.suspend((err: BusinessError, result: boolean) => {
      if (err) {
        console.error(`Failed to pause the download task. Code: ${err.code}, message: ${err.message}`);
        return;
      }
      console.info('Succeeded in pausing the download task.');
    });
  }).catch((err: BusinessError) => {
    console.error(`Failed to request the download. Code: ${err.code}, message: ${err.message}`);
  })
} catch (err) {
  console.error(`Failed to request the download. err: ${JSON.stringify(err)}`);
}
  ```

> **NOTE**
>
> The scenarios for triggering error code 401 do not actually exist. Therefore, `401 the parameters check fails` is removed from API version 12.


### restore<sup>9+</sup>

restore(): Promise&lt;boolean&gt;

Restores this download task. This API uses a promise to return the result.

**Required permissions**: ohos.permission.INTERNET

**System capability**: SystemCapability.MiscServices.Download

**Return value**

| Type| Description|
| -------- | -------- |
| Promise&lt;boolean&gt; | Promise used to return the result. The value **true** indicates that the operation is successful, and the value **false** indicates the opposite.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 201 | the permissions check fails |

**Example**

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

try {
  // Replace the URL with the HTTP address of the real server.
  request.downloadFile(getContext(), { url: 'https://xxxx/xxxx.hap' }).then((data: request.DownloadTask) => {
    let downloadTask: request.DownloadTask = data;
    downloadTask.restore().then((result: boolean) => {
      console.info('Succeeded in resuming the download task.')
    }).catch((err: BusinessError) => {
      console.error(`Failed to resume the download task. Code: ${err.code}, message: ${err.message}`);
    });
  }).catch((err: BusinessError) => {
    console.error(`Failed to request the download. Code: ${err.code}, message: ${err.message}`);
  })
} catch (err) {
  console.error(`Failed to request the download. err: ${JSON.stringify(err)}`);
}
  ```

> **NOTE**
>
> The scenarios for triggering error code 401 do not actually exist. Therefore, `401 the parameters check fails` is removed from API version 12.


### restore<sup>9+</sup>

restore(callback: AsyncCallback&lt;boolean&gt;): void

Restores this download task. This API uses an asynchronous callback to return the result.

**Required permissions**: ohos.permission.INTERNET

**System capability**: SystemCapability.MiscServices.Download

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| callback | AsyncCallback&lt;boolean&gt; | Yes| Callback used to return the result. The value **true** indicates that the operation is successful, and the value **false** indicates the opposite.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 201 | the permissions check fails |

**Example**

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

try {
  // Replace the URL with the HTTP address of the real server.
  request.downloadFile(getContext(), { url: 'https://xxxx/xxxx.hap' }).then((data: request.DownloadTask) => {
    let downloadTask: request.DownloadTask = data;
    downloadTask.restore((err: BusinessError, result: boolean) => {
      if (err) {
        console.error(`Failed to resume the download task. Code: ${err.code}, message: ${err.message}`);
        return;
      }
      console.info('Succeeded in resuming the download task.');
    });
  }).catch((err: BusinessError) => {
    console.error(`Failed to request the download. Code: ${err.code}, message: ${err.message}`);
  })
} catch (err) {
  console.error(`Failed to request the download. err: ${JSON.stringify(err)}`);
}
  ```

> **NOTE**
>
> The scenarios for triggering error code 401 do not actually exist. Therefore, `401 the parameters check fails` is removed from API version 12.


### remove<sup>(deprecated)</sup>

remove(): Promise&lt;boolean&gt;

Removes this download task. This API uses a promise to return the result.

> **NOTE**
>
> This API is deprecated since API version 9. You are advised to use [delete<sup>9+</sup>](#delete9-2) instead.

**Required permissions**: ohos.permission.INTERNET

**System capability**: SystemCapability.MiscServices.Download

**Return value**

| Type| Description|
| -------- | -------- |
| Promise&lt;boolean&gt; | Promise used to return the result. The value **true** indicates that the operation is successful, and the value **false** indicates the opposite.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 201 | the permissions check fails |

**Example**

  ```js
  downloadTask.remove().then((result) => {
    console.info('Succeeded in removing the download task.');
  }).catch ((err) => {
    console.error(`Failed to remove the download task. Code: ${err.code}, message: ${err.message}`);
  });
  ```


### remove<sup>(deprecated)</sup>

remove(callback: AsyncCallback&lt;boolean&gt;): void

Removes this download task. This API uses an asynchronous callback to return the result.

> **NOTE**
>
> This API is deprecated since API version 9. You are advised to use [delete<sup>9+</sup>](#delete9-3) instead.

**Required permissions**: ohos.permission.INTERNET

**System capability**: SystemCapability.MiscServices.Download

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| callback | AsyncCallback&lt;boolean&gt; | Yes| Callback used to return the result. The value **true** indicates that the operation is successful, and the value **false** indicates the opposite.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 201 | the permissions check fails |

**Example**

  ```js
  downloadTask.remove((err, result)=>{
    if(err) {
      console.error(`Failed to remove the download task. Code: ${err.code}, message: ${err.message}`);
      return;
    }
    console.info('Succeeded in removing the download task.');
  });
  ```


### query<sup>(deprecated)</sup>

query(): Promise&lt;DownloadInfo&gt;

Queries this download task. This API uses a promise to return the result.

> **NOTE**
>
> This API is supported since API version 7 and is deprecated since API version 9. You are advised to use [getTaskInfo<sup>9+</sup>](#gettaskinfo9) instead.

**Required permissions**: ohos.permission.INTERNET

**System capability**: SystemCapability.MiscServices.Download

**Return value**

| Type| Description|
| -------- | -------- |
| Promise&lt;[DownloadInfo](#downloadinfo7)&gt; | Promise used to return the **DownloadInfo** object.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 201 | the permissions check fails |

**Example**

  ```js
  downloadTask.query().then((downloadInfo) => {    
    console.info('Succeeded in querying the download task.')
  }) .catch((err) => {
    console.error(`Failed to query the download task. Code: ${err.code}, message: ${err.message}`)
  });
  ```


### query<sup>(deprecated)</sup>

query(callback: AsyncCallback&lt;DownloadInfo&gt;): void

Queries this download task. This API uses an asynchronous callback to return the result.

> **NOTE**
>
> This API is supported since API version 7 and is deprecated since API version 9. You are advised to use [getTaskInfo<sup>9+</sup>](#gettaskinfo9-1) instead.

**Required permissions**: ohos.permission.INTERNET

**System capability**: SystemCapability.MiscServices.Download

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| callback | AsyncCallback&lt;[DownloadInfo](#downloadinfo7)&gt; | Yes| Callback used to return the result. If the operation is successful, **err** is **undefined** and **data** is the **DownloadInfo** object obtained. Otherwise, **err** is an error object.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 201 | the permissions check fails |

**Example**

  ```js
  downloadTask.query((err, downloadInfo)=>{
    if(err) {
      console.error(`Failed to query the download mimeType. Code: ${err.code}, message: ${err.message}`);
    } else {
      console.info('Succeeded in querying the download task.');
    }
  });
  ```


### queryMimeType<sup>(deprecated)</sup>

queryMimeType(): Promise&lt;string&gt;

Queries the **MimeType** of this download task. This API uses a promise to return the result.

> **NOTE**
>
> This API is supported since API version 7 and is deprecated since API version 9. You are advised to use [getTaskMimeType<sup>9+</sup>](#gettaskmimetype9) instead.

**Required permissions**: ohos.permission.INTERNET

**System capability**: SystemCapability.MiscServices.Download

**Return value**

| Type| Description|
| -------- | -------- |
| Promise&lt;string&gt; | Promise used to return the **MimeType** object.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 201 | the permissions check fails |

**Example**

  ```js
  downloadTask.queryMimeType().then((data) => {    
    console.info('Succeeded in querying the download MimeType.');
  }).catch((err) => {
    console.error(`Failed to query the download MimeType. Code: ${err.code}, message: ${err.message}`)
  });
  ```


### queryMimeType<sup>(deprecated)</sup>

queryMimeType(callback: AsyncCallback&lt;string&gt;): void;

Queries the **MimeType** of this download task. This API uses an asynchronous callback to return the result.

> **NOTE**
>
> This API is supported since API version 7 and is deprecated since API version 9. You are advised to use [getTaskMimeType<sup>9+</sup>](#gettaskmimetype9-1) instead.

**Required permissions**: ohos.permission.INTERNET

**System capability**: SystemCapability.MiscServices.Download

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| callback | AsyncCallback&lt;string&gt; | Yes| Callback used to return the result. If the operation is successful, **err** is **undefined** and data is the **MimeType** object obtained. Otherwise, **err** is an error object.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 201 | the permissions check fails |

**Example**

  ```js
  downloadTask.queryMimeType((err, data)=>{
    if(err) {
      console.error(`Failed to query the download mimeType. Code: ${err.code}, message: ${err.message}`);
    } else {
      console.info('Succeeded in querying the download mimeType.');
    }
  });
  ```


### pause<sup>(deprecated)</sup>

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

Pauses this download task. This API uses a promise to return the result.

> **NOTE**
>
> This API is supported since API version 7 and is deprecated since API version 9. You are advised to use [suspend<sup>9+</sup>](#suspend9) instead.

**Required permissions**: ohos.permission.INTERNET

**System capability**: SystemCapability.MiscServices.Download

**Return value**

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

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 201 | the permissions check fails |

**Example**

  ```js
  downloadTask.pause().then((result) => {    
    console.info('Succeeded in pausing the download task.');
  }).catch((err) => {
    console.error(`Failed to pause the download task. Code: ${err.code}, message: ${err.message}`);
  });
  ```


### pause<sup>(deprecated)</sup>

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

> **NOTE**
>
> This API is supported since API version 7 and is deprecated since API version 9. You are advised to use [suspend<sup>9+</sup>](#suspend9-1) instead.

Pauses this download task. This API uses an asynchronous callback to return the result.

**Required permissions**: ohos.permission.INTERNET

**System capability**: SystemCapability.MiscServices.Download

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| callback | AsyncCallback&lt;void&gt; | Yes| Callback used to return the result. If the operation is successful, **err** is **undefined**. Otherwise, **err** is an error object.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 201 | the permissions check fails |

**Example**

  ```js
  downloadTask.pause((err, result)=>{
    if(err) {
      console.error(`Failed to pause the download task. Code: ${err.code}, message: ${err.message}`);
      return;
    }
    console.info('Succeeded in pausing the download task.');
  });
  ```


### resume<sup>(deprecated)</sup>

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

Resumes this download task. This API uses a promise to return the result.

> **NOTE**
>
> This API is supported since API version 7 and is deprecated since API version 9. You are advised to use [restore<sup>9+</sup>](#restore9) instead.

**Required permissions**: ohos.permission.INTERNET

**System capability**: SystemCapability.MiscServices.Download

**Return value**

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

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 201 | the permissions check fails |

**Example**

  ```js
  downloadTask.resume().then((result) => {
    console.info('Succeeded in resuming the download task.')
  }).catch((err) => {
    console.error(`Failed to resume the download task. Code: ${err.code}, message: ${err.message}`);
  });
  ```


### resume<sup>(deprecated)</sup>

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

> **NOTE**
>
> This API is supported since API version 7 and is deprecated since API version 9. You are advised to use [restore<sup>9+</sup>](#restore9-1) instead.

Resumes this download task. This API uses an asynchronous callback to return the result.

**Required permissions**: ohos.permission.INTERNET

**System capability**: SystemCapability.MiscServices.Download

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| callback | AsyncCallback&lt;void&gt; | Yes| Callback used to return the result. If the operation is successful, **err** is **undefined**. Otherwise, **err** is an error object.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 201 | the permissions check fails |

**Example**

  ```js
  downloadTask.resume((err, result)=>{
    if (err) {
      console.error(`Failed to resume the download task. Code: ${err.code}, message: ${err.message}`);
      return;
    }
    console.info('Succeeded in resuming the download task.');
  });
  ```


## DownloadConfig
Defines the download task configuration.

**System capability**: SystemCapability.MiscServices.Download

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| url | string | Yes| Resource URL. The value contains a maximum of 2048 characters.|
| header | Object | No| HTTPS flag header to be included in the download request.|
| enableMetered | boolean | No| Whether download is allowed on a metered connection. The default value is **false**. In general cases, a mobile data connection is metered, while a Wi-Fi connection is not.<br>- **true**: allowed<br>- **false**: not allowed|
| enableRoaming | boolean | No| Whether download is allowed on a roaming network. The default value is **false**.<br>- **true**: allowed<br>- **false**: not allowed|
| description | string | No| Description of the download session.|
| filePath<sup>7+</sup> | string | No| Path where the downloaded file is stored. The default value is the cache directory of the caller (that is, the input **context**). The default file name is the part truncated from the last slash (/) in the URL.<br>- In the FA model, use [context](../apis-ability-kit/js-apis-inner-app-context.md#contextgetcachedir) to obtain the application storage path.<br>- In the stage model, use [AbilityContext](../apis-ability-kit/js-apis-inner-application-context.md) to obtain the application storage path.|
| networkType | number | No| Network type allowed for the download. The default value is **NETWORK_MOBILE and NETWORK_WIFI**.<br>- NETWORK_MOBILE: 0x00000001<br>- NETWORK_WIFI: 0x00010000|
| title | string | No| Download task name.|
| background<sup>9+</sup> | boolean | No| Whether to enable background task notification so that the download status is displayed in the notification panel. The default value is false.|


## DownloadInfo<sup>7+</sup>
Defines the download task information, which is the callback parameter of the [getTaskInfo<sup>9+</sup>](#gettaskinfo9) API.

**System capability**: SystemCapability.MiscServices.Download

| Name| Type|Mandatory|  Description|
| -------- | -------- | -------- | -------- |
| downloadId | number |Yes| ID of the download task.|
| failedReason | number|Yes| Cause of the download failure. The value can be any constant in [Download Error Codes](#constants).|
| fileName | string |Yes| Name of the downloaded file.|
| filePath | string |Yes| URI of the saved file.|
| pausedReason | number |Yes| Cause of download pause. The value can be any constant in [Causes of Download Pause](#constants).|
| status | number |Yes| Download task status code. The value can be any constant in [Download Task Status Codes](#constants).|
| targetURI | string |Yes| URI of the downloaded file.|
| downloadTitle | string |Yes| Name of the download task.|
| downloadTotalBytes | number |Yes| Total size of the files to download, in bytes.|
| description | string |Yes| Description of the download task.|
| downloadedBytes | number |Yes| Real-time download size, in bytes.|

## Action<sup>10+</sup>  

Defines action options.

**Atomic service API**: This API can be used in atomic services since API version 11.

**System capability**: SystemCapability.Request.FileTransferAgent

| Name| Value|Description|
| -------- | -------- |-------- |
| DOWNLOAD | 0 |Download.|
| UPLOAD | 1 |Upload.|


## Mode<sup>10+</sup>  
Defines mode options.<br>
After an application is switched to the background for a period of time, background tasks are not affected but foreground tasks will fail or pause.

**Atomic service API**: This API can be used in atomic services since API version 11.

**System capability**: SystemCapability.Request.FileTransferAgent

| Name| Value|Description|
| -------- | -------- |-------- |
| BACKGROUND | 0 |Background task.|
| FOREGROUND | 1 |Foreground task.|

## Network<sup>10+</sup>  

Defines network options.<br>
If the network does not meet the preset conditions, the tasks that have not been executed will await for execution, and the tasks that are being executed will fail or pause.

**Atomic service API**: This API can be used in atomic services since API version 11.

**System capability**: SystemCapability.Request.FileTransferAgent

| Name| Value|Description|
| -------- | -------- |-------- |
| ANY | 0 |Network of any type.|
| WIFI | 1 |Wi-Fi network.|
| CELLULAR | 2 |Cellular data network.|

## BroadcastEvent<sup>11+</sup>

Defines a custom system event. You can use a common event API to obtain the event.
The upload and download SA has the **ohos.permission.SEND_TASK_COMPLETE_EVENT** permission. You can configure the level-2 configuration file to which the metadata of an event points to intercept other event senders.

You can use the **CommonEventData** type to transmit data related to common events. The members in **CommonEventData** are different from those described in [CommonEventData](js-apis-inner-commonEvent-commonEventData.md). Specifically, **CommonEventData.code** indicates the task status, which is **0x40 COMPLETE** or **0x41 FAILED**, and **CommonEventData.data** indicates the task ID.

<!--Del-->
For details about event configuration information, see [Subscribing to Common Events in Static Mode (for System Applications Only)](../../basic-services/common-event/common-event-static-subscription.md).<!--DelEnd-->

**System capability**: SystemCapability.Request.FileTransferAgent

| Name| Value| Description       |
| -------- | ------- |-----------|
| COMPLETE | 'ohos.request.event.COMPLETE' | Task completion event.|

## FileSpec<sup>10+</sup> 
Provides the file information of a table item.

**Atomic service API**: This API can be used in atomic services since API version 11.

**System capability**: SystemCapability.Request.FileTransferAgent

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| path | string | Yes| File path:<br>- Relative path, which is in the cache directory of the caller, for example, **./xxx/yyy/zzz.html** or **xxx/yyy/zzz.html**.<br>- Internal protocol path, which can be **internal://** or its subdirectory. **internal** indicates the cache directory of the caller (that is, the input **context**), and **internal://cache** corresponds to **context.cacheDir**, for example, **internal://cache/path/to/file.txt**.<br>- Application sandbox directory. Only the **base** directory and its subdirectories are supported, for example, **/data/storage/el1/base/path/to/file.txt**.<br>- File protocol path, which must match the application bundle name. Only the **base** directory and its subdirectories are supported, for example, **file://com.example.test/data/storage/el2/base/file.txt**.<br>- User public file, for example, **file://media/Photo/path/to/file.img**. Only frontend tasks are supported.|
| mimeType | string | No| MIME type of the file, which is obtained from the file name.|
| filename | string | No| File name. The default value is obtained from the file path.|
| extras | object | No| Additional information. This parameter is not included in HTTP requests.|


## FormItem<sup>10+</sup> 
Describes the form item of a task.

**Atomic service API**: This API can be used in atomic services since API version 11.

**System capability**: SystemCapability.Request.FileTransferAgent

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| name | string | Yes| Form parameter name.|
| value | string \| [FileSpec](#filespec10) \| Array&lt;[FileSpec](#filespec10)&gt; | Yes| Form parameter value.|


## Config<sup>10+</sup> 
Provides the configuration information of an upload or download task.

**System capability**: SystemCapability.Request.FileTransferAgent

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| action | [Action](#action10) | Yes| Task action.<br>- **UPLOAD**<br>- **DOWNLOAD**<br>**Atomic service API**: This API can be used in atomic services since API version 11.|
| url | string | Yes| Resource URL. The value contains a maximum of 2048 characters.<br>**Atomic service API**: This API can be used in atomic services since API version 11.|
| title | string | No| Task title. The value contains a maximum of 256 characters. The default value is **upload** or **download** in lowercase. Set the value to that of **action**.<br>**Atomic service API**: This API can be used in atomic services since API version 11.|
| description | string | No| Task description. The value contains a maximum of 1024 characters. The default value is a null string.<br>**Atomic service API**: This API can be used in atomic services since API version 11.|
| mode | [Mode](#mode10) | No| Task mode. The default mode is background.<br>**Atomic service API**: This API can be used in atomic services since API version 11.|
| overwrite | boolean | No| Whether to overwrite an existing file during the download. The default value is **false**.<br>- **true**: Overwrite the existing file.<br>- **false**: Do not overwrite the existing file. In this case, the download fails.<br>**Atomic service API**: This API can be used in atomic services since API version 11.|
| method | string | No| Standard HTTP method for the task. The value can be **GET**, **POST**, or **PUT**, which is case-insensitive.<br>- If the task is an upload, use **PUT** or **POST**. The default value is **PUT**.<br>- If the task is a download, use **GET** or **POST**. The default value is **GET**.<br>**Atomic service API**: This API can be used in atomic services since API version 11.|
| headers | object | No| HTTP headers to be included in the task.<br>- If the task is an upload, the default **Content-Type** is **multipart/form-data**.<br>- If the task is a download, the default **Content-Type** is **application/json**.<br>**Atomic service API**: This API can be used in atomic services since API version 11.|
| data | string \| Array&lt;[FormItem](#formitem10)&gt; | No| Task data.<br>- If the task is a download, the value is a string, typically in JSON format (an object will be converted to a JSON string); the default value is null.<br>- If the task is an upload, the value is Array<[FormItem](#formitem10)>; the default value is null.<br>**Atomic service API**: This API can be used in atomic services since API version 11.|
| saveas | string | No| Path for storing downloaded files. The options are as follows:<br>- Relative path, which is in the cache directory of the caller, for example, **./xxx/yyy/zzz.html** or **xxx/yyy/zzz.html**.<br>- Internal protocol path, which can be **internal://** or its subdirectory. **internal** indicates the cache directory of the caller (that is, the input **context**), and **internal://cache** corresponds to **context.cacheDir**, for example, **internal://cache/path/to/file.txt**.<br>- Application sandbox directory. Only the **base** directory and its subdirectories are supported, for example, **/data/storage/el1/base/path/to/file.txt**.<br>- File protocol path, which must match the application bundle name. Only the **base** directory and its subdirectories are supported, for example, **file://com.example.test/data/storage/el2/base/file.txt**.<br>The default value is the cache directory of the caller (that is, the input **context**). The default file name is the part truncated from the last slash (/) in the URL.<br>**Atomic service API**: This API can be used in atomic services since API version 11.|
| network | [Network](#network10) | No| Network used for the task. The default value is **ANY** (Wi-Fi or cellular).<br>**Atomic service API**: This API can be used in atomic services since API version 11.|
| metered | boolean | No| Whether the task is allowed on a metered connection. The default value is **false**.<br>- **true**: task allowed on a metered connection.<br>- **false**: task not allowed on a metered connection.<br>**Atomic service API**: This API can be used in atomic services since API version 11.|
| roaming | boolean | No| Whether the task is allowed on a roaming network. The default value is **true**.<br>- **true**: task allowed on a roaming network.<br>- **false**: task not allowed on a metered connection.<br>**Atomic service API**: This API can be used in atomic services since API version 11.|
| retry | boolean | No| Whether automatic retry is enabled for the task. This parameter is only applicable to background tasks. The default value is **true**.<br>- **true**: automatic retry is enabled.<br>- **false**: automatic retry is disabled.<br>**Atomic service API**: This API can be used in atomic services since API version 11.|
| redirect | boolean | No| Whether redirection is allowed. The default value is **true**.<br>- **true**: redirection allowed.<br>- **false**: redirection not allowed.<br>**Atomic service API**: This API can be used in atomic services since API version 11.|
| proxy<sup>12+</sup> | string | No| Proxy address. The value contains a maximum of 512 characters.<br>It is in the format of http://\<domain or address\>:\<port\>. By default, this parameter is left blank.|
| index | number | No| Path index of the task. It is usually used for resumable downloads. The default value is **0**.<br>**Atomic service API**: This API can be used in atomic services since API version 11.|
| begins | number | No| File start point of the task. It is usually used for resumable downloads. The default value is **0**. The value is a closed interval.<br>- If the task is a download, the value is obtained by sending an HTTP range request to read the start position when the server starts to download files.<br>- If the task is an upload, the value is obtained at the beginning of the upload.<br>**Atomic service API**: This API can be used in atomic services since API version 11.|
| ends | number | No| File end point of the task. It is usually used for resumable downloads. The default value is **-1**. The value is a closed interval.<br>- If the task is a download, the value is obtained by sending an HTTP range request to read the end position when the server starts to download files.<br>- If the task is an upload, the value is obtained at the end of the upload.<br>**Atomic service API**: This API can be used in atomic services since API version 11.|
| gauge | boolean | No| Whether to send progress notifications. This parameter applies only to background tasks. The default value is **false**.<br>- **false**: Progress notifications are not sent. This means that a notification is sent only to indicate the result of the total task.<br>- **true**: Progress notifications are sent to indicate the result of each file.<br>**Atomic service API**: This API can be used in atomic services since API version 11.|
| precise | boolean | No| - If this parameter is set to **true**, the task fails when the file size cannot be obtained.<br>- If this parameter is set to **false**, the task continues when the file size is set to **-1**.<br>The default value is **false**.<br>**Atomic service API**: This API can be used in atomic services since API version 11.|
| token | string | No| Token of the task. If the task has a token configured, this token is required for query of the task. The value contains 8 to 2048 bytes. This parameter is left empty by default.<br>**Atomic service API**: This API can be used in atomic services since API version 11.|
| priority<sup>11+</sup> | number | No| Priority of the task. For tasks in the same mode, a smaller value indicates a higher priority.<br>Default value: **0**|
| extras | object | No| Additional information of the task. This parameter is left empty by default.<br>**Atomic service API**: This API can be used in atomic services since API version 11.|

## State<sup>10+</sup>  

Defines the current task status.

**Atomic service API**: This API can be used in atomic services since API version 11.

**System capability**: SystemCapability.Request.FileTransferAgent

| Name| Value|Description|
| -------- | -------- |-------- |
| INITIALIZED | 0x00 |The task is initialized based on the configuration specified in [Config](#config10).|
| WAITING | 0x10 |The task lacks resources for running or the resources for retries do not match the network status.|
| RUNNING | 0x20 |The task is being executed.|
| RETRYING | 0x21 |The task has failed at least once and is being executed again.|
| PAUSED | 0x30 |The task is suspended and will be resumed later.|
| STOPPED | 0x31 |The task is stopped.|
| COMPLETED | 0x40 |The task is complete.|
| FAILED | 0x41 |The task fails.|
| REMOVED | 0x50 |The task is removed.|


## Progress<sup>10+</sup> 
Describes the data structure of the task progress.

**Atomic service API**: This API can be used in atomic services since API version 11.

**System capability**: SystemCapability.Request.FileTransferAgent

| Name| Type| Mandatory| Description                                                                 |
| -------- | -------- | -------- |---------------------------------------------------------------------|
| state | [State](#state10) | Yes| Current task status.                                                           |
| index | number | Yes| Index of the file that is being processed in the task.                                                    |
| processed | number | Yes| Size of processed data in the current file in the task, in bytes.                                              |
| sizes | Array&lt;number&gt; | Yes| Size of a file in a task, in bytes. If the server uses the chunk mode for data transmission and the total file size cannot be obtained from the request header, the value of **sizes** is treated as **-1**.|
| extras | object | No| Extra information of the task, for example, the header and body of the response from the server.                                    |


## Faults<sup>10+</sup>  

Defines the cause of a task failure.

**Atomic service API**: This API can be used in atomic services since API version 11.

**System capability**: SystemCapability.Request.FileTransferAgent

| Name| Value| Description                                                                            |
| -------- | -------- |--------------------------------------------------------------------------------|
| OTHERS | 0xFF | Other fault.                                                                       |
| DISCONNECTED | 0x00 | Network disconnection.                                                                     |
| TIMEOUT | 0x10 | Timeout.                                                                       |
| PROTOCOL | 0x20 | Protocol error, for example, an internal server error (500) or a data range that cannot be processed (416).                                       |
| PARAM<sup>12+</sup> | 0x30 | Parameter error, for example, incorrect URL format.<br>**Atomic service API**: This API can be used in atomic services since API version 12.         |
| FSIO | 0x40 | File system I/O error, for example, an error that occurs during the open, search, read, write, or close operation.                                                  |
| DNS<sup>12+</sup> | 0x50 | DNS resolution error.<br>**Atomic service API**: This API can be used in atomic services since API version 12.                 |
| TCP<sup>12+</sup> | 0x60 | TCP connection error.<br>**Atomic service API**: This API can be used in atomic services since API version 12.             |
| SSL<sup>12+</sup> | 0x70 | SSL connection error, for example, a certificate error or certificate verification failure.<br>**Atomic service API**: This API can be used in atomic services since API version 12.|
| REDIRECT<sup>12+</sup> | 0x80 | Redirection error.<br>**Atomic service API**: This API can be used in atomic services since API version 12.                   |

> **NOTE**
>
> In API version 12 or earlier, only serial connection to the IP addresses associated with the specified domain name is supported, and the connection time for a single IP address is not controllable. If the first IP address returned by the DNS is blocked, a handshake timeout may occur, leading to a **TIMEOUT** error.

## Filter<sup>10+</sup>
Defines the filter criteria.

**System capability**: SystemCapability.Request.FileTransferAgent

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| before | number | No| Unix timestamp of the end time, in milliseconds. The default value is the invoking time.|
| after | number | No| Unix timestamp of the start time, in milliseconds. The default value is the invoking time minus 24 hours.|
| state | [State](#state10) | No| Task state.|
| action | [Action](#action10) | No| Task action.<br>- **UPLOAD**<br>- **DOWNLOAD**|
| mode | [Mode](#mode10) | No| Task mode.<br>- **FOREGROUND**: foreground task.<br>- **BACKGROUND**: background task.<br>- No value: All tasks are queried.|

## TaskInfo<sup>10+</sup> 
Defines the data structure of the task information for query. The fields available vary depending on the query type.

**System capability**: SystemCapability.Request.FileTransferAgent

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| saveas | string | No| Path for storing downloaded files.|
| url | string | No| Task URL.<br>It can be obtained through [request.agent.show<sup>10+</sup>](#requestagentshow10-1) or [request.agent.touch<sup>10+</sup>](#requestagenttouch10-1).|
| data | string \| Array&lt;[FormItem](#formitem10)&gt; | No| Task value.<br>It can be obtained through [request.agent.show<sup>10+</sup>](#requestagentshow10-1) or [request.agent.touch<sup>10+</sup>](#requestagenttouch10-1).|
| tid | string | Yes| Task ID.|
| title | string | Yes| Task title.|
| description | string | Yes| Task description.|
| action | [Action](#action10) | Yes| Task action.<br>- **UPLOAD**<br>- **DOWNLOAD**|
| mode | [Mode](#mode10) | Yes| Task mode.<br>- **FOREGROUND**: foreground task.<br>- **BACKGROUND**: background task.|
| priority<sup>11+</sup> | number | Yes| Task priority. The priority of a foreground task is higher than that of a background task. For tasks in the same mode, a smaller value indicates a higher priority.|
| mimeType | string | Yes| MIME type in the task configuration.|
| progress | [Progress](#progress10) | Yes| Task progress.|
| gauge | boolean | Yes| Whether to send progress notifications. This parameter applies only to background tasks.|
| ctime | number | Yes | Unix timestamp when the task is created, in milliseconds. The value is generated by the system of the current device.<br/>**NOTE**<br>When [request.agent.search<sup>10+</sup>](#requestagentsearch10-1) is used for query, this value must be within the range of [after,before] for the task ID to be obtained. For details about **before** and **after**, see [Filter](#filter10). |
| mtime | number | Yes| Unix timestamp when the task state changes, in milliseconds. The value is generated by the system of the current device.|
| retry | boolean | Yes| Whether automatic retry is enabled for the task. This parameter applies only to background tasks.|
| tries | number | Yes| Number of retries of the task.|
| faults | [Faults](#faults10) | Yes| Failure cause of the task.|
| reason | string | Yes| Reason why the task is waiting, failed, stopped, or paused.|
| extras | object | No| Extra information of the task.|


## HttpResponse<sup>12+</sup> 
Data structure of the task response header.

**Atomic service API**: This API can be used in atomic services since API version 12.

**System capability**: SystemCapability.Request.FileTransferAgent

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| version | string | Yes| HTTP version.|
| statusCode | number | Yes| HTTP response status code.|
| reason | string | Yes| HTTP response cause.|
| headers | Map&lt;string, Array&lt;string&gt;&gt; | Yes| HTTP response header.|

## Task<sup>10+</sup> 
Implements an upload or download task. Before using this API, you must obtain a **Task** object, from a promise through [request.agent.create<sup>10+</sup>](#requestagentcreate10-1) or from a callback through [request.agent.create<sup>10+</sup>](#requestagentcreate10).

### Attributes
Task attributes include the task ID and task configuration.

**Atomic service API**: This API can be used in atomic services since API version 11.

**System capability**: SystemCapability.Request.FileTransferAgent

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| tid | string | Yes| Task ID, which is unique in the system and is automatically generated by the system.|
| config | [Config](#config10) | Yes| Task configuration.|

> **NOTE**
>
> The **Task** object and its mounting callback function are released and automatically reclaimed by the system after the **remove** method is called.

### on('progress')<sup>10+</sup>

on(event: 'progress', callback: (progress: [Progress](#progress10)) =&gt; void): void

Subscribes to task progress changes. This API uses an asynchronous callback to return the result.

**Atomic service API**: This API can be used in atomic services since API version 11.

**System capability**: SystemCapability.Request.FileTransferAgent

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| event | string | Yes| Type of the event to subscribe to.<br>The value is **'progress'**, indicating the task progress.|
| callback | function | Yes| Callback used to return the data structure of the task progress.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 401 | Parameter error. Possible causes: 1. Missing mandatory parameters 2. Incorrect parameter type 3. Parameter verification failed |

**Example**

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

  let attachments: Array<request.agent.FormItem> = [{
    name: "taskOnTest",
    value: {
      filename: "taskOnTest.avi",
      mimeType: "application/octet-stream",
      path: "./taskOnTest.avi",
    }
  }];
  let config: request.agent.Config = {
    action: request.agent.Action.UPLOAD,
    url: 'http://127.0.0.1', // Replace the URL with the HTTP address of the real server.
    title: 'taskOnTest',
    description: 'Sample code for event listening',
    mode: request.agent.Mode.FOREGROUND,
    overwrite: false,
    method: "PUT",
    data: attachments,
    saveas: "./",
    network: request.agent.Network.CELLULAR,
    metered: false,
    roaming: true,
    retry: true,
    redirect: true,
    index: 0,
    begins: 0,
    ends: -1,
    gauge: false,
    precise: false,
    token: "it is a secret"
  };
  let createOnCallback = (progress: request.agent.Progress) => {
    console.info('upload task progress.');
  };
  request.agent.create(getContext(), config).then((task: request.agent.Task) => {
    task.on('progress', createOnCallback);
    console.info(`Succeeded in creating a upload task. result: ${task.tid}`);
    task.start();
  }).catch((err: BusinessError) => {
    console.error(`Failed to create a upload task, Code: ${err.code}, message: ${err.message}`);
  });
  ```

> **NOTE**
>
> For details about how to obtain the context in the example, see [Obtaining the Context of UIAbility](../../application-models/uiability-usage.md#obtaining-the-context-of-uiability).

### on('completed')<sup>10+</sup>

on(event: 'completed', callback: (progress: [Progress](#progress10)) =&gt; void): void

Subscribes to task completion events. This API uses an asynchronous callback to return the result.

**Atomic service API**: This API can be used in atomic services since API version 11.

**System capability**: SystemCapability.Request.FileTransferAgent

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| event | string | Yes| Type of the event to subscribe to.<br>The value is **'completed'**, indicating task completion.|
| callback | function | Yes| Callback used to return the data structure of the task progress.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 401 | Parameter error. Possible causes: 1. Missing mandatory parameters 2. Incorrect parameter type 3. Parameter verification failed |

**Example**

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

  let attachments: Array<request.agent.FormItem> = [{
    name: "taskOnTest",
    value: {
      filename: "taskOnTest.avi",
      mimeType: "application/octet-stream",
      path: "./taskOnTest.avi",
    }
  }];
  let config: request.agent.Config = {
    action: request.agent.Action.UPLOAD,
    url: 'http://127.0.0.1', // Replace the URL with the HTTP address of the real server.
    title: 'taskOnTest',
    description: 'Sample code for event listening',
    mode: request.agent.Mode.FOREGROUND,
    overwrite: false,
    method: "PUT",
    data: attachments,
    saveas: "./",
    network: request.agent.Network.CELLULAR,
    metered: false,
    roaming: true,
    retry: true,
    redirect: true,
    index: 0,
    begins: 0,
    ends: -1,
    gauge: false,
    precise: false,
    token: "it is a secret"
  };
  let createOnCallback = (progress: request.agent.Progress) => {
    console.info('upload task completed.');
  };
  request.agent.create(getContext(), config).then((task: request.agent.Task) => {
    task.on('completed', createOnCallback);
    console.info(`Succeeded in creating a upload task. result: ${task.tid}`);
    task.start();
  }).catch((err: BusinessError) => {
    console.error(`Failed to create a upload task, Code: ${err.code}, message: ${err.message}`);
  });
  ```

> **NOTE**
>
> For details about how to obtain the context in the example, see [Obtaining the Context of UIAbility](../../application-models/uiability-usage.md#obtaining-the-context-of-uiability).

### on('failed')<sup>10+</sup>

on(event: 'failed', callback: (progress: [Progress](#progress10)) =&gt; void): void

Subscribes to task failure events. This API uses an asynchronous callback to return the result. You can call [request.agent.show<sup>10+</sup>](#requestagentshow10-1) to check the error.

**Atomic service API**: This API can be used in atomic services since API version 11.

**System capability**: SystemCapability.Request.FileTransferAgent

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| event | string | Yes| Type of the event to subscribe to.<br>The value is **'failed'**, indicating task failure.|
| callback | function | Yes| Callback used to return the data structure of the task progress.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 401 | Parameter error. Possible causes: 1. Missing mandatory parameters 2. Incorrect parameter type 3. Parameter verification failed |

**Example**

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

  let attachments: Array<request.agent.FormItem> = [{
    name: "taskOnTest",
    value: {
      filename: "taskOnTest.avi",
      mimeType: "application/octet-stream",
      path: "./taskOnTest.avi",
    }
  }];
  let config: request.agent.Config = {
    action: request.agent.Action.UPLOAD,
    url: 'http://127.0.0.1', // Replace the URL with the HTTP address of the real server.
    title: 'taskOnTest',
    description: 'Sample code for event listening',
    mode: request.agent.Mode.FOREGROUND,
    overwrite: false,
    method: "PUT",
    data: attachments,
    saveas: "./",
    network: request.agent.Network.CELLULAR,
    metered: false,
    roaming: true,
    retry: true,
    redirect: true,
    index: 0,
    begins: 0,
    ends: -1,
    gauge: false,
    precise: false,
    token: "it is a secret"
  };
  let createOnCallback = (progress: request.agent.Progress) => {
    console.info('upload task failed.');
  };
  request.agent.create(getContext(), config).then((task: request.agent.Task) => {
    task.on('failed', createOnCallback);
    console.info(`Succeeded in creating a upload task. result: ${task.tid}`);
    task.start();
  }).catch((err: BusinessError) => {
    console.error(`Failed to create a upload task, Code: ${err.code}, message: ${err.message}`);
  });
  ```

> **NOTE**
>
> For details about how to obtain the context in the example, see [Obtaining the Context of UIAbility](../../application-models/uiability-usage.md#obtaining-the-context-of-uiability).

### on('pause')<sup>11+</sup>

on(event: 'pause', callback: (progress: [Progress](#progress10)) =&gt; void): void

Subscribes to task pause events. This API uses an asynchronous callback to return the result.

**System capability**: SystemCapability.Request.FileTransferAgent

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| event | string | Yes| Type of the event to subscribe to.<br>- **'pause'**: task pause event.|
| callback | function | Yes| Callback used to return the data structure of the task progress.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 401 | Parameter error. Possible causes: 1. Missing mandatory parameters 2. Incorrect parameter type 3. Parameter verification failed |

**Example**

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

  let attachments: Array<request.agent.FormItem> = [{
    name: "taskOnTest",
    value: {
      filename: "taskOnTest.avi",
      mimeType: "application/octet-stream",
      path: "./taskOnTest.avi",
    }
  }];
  let config: request.agent.Config = {
    action: request.agent.Action.UPLOAD,
    url: 'http://127.0.0.1', // Replace the URL with the HTTP address of the real server.
    title: 'taskOnTest',
    description: 'Sample code for event listening',
    mode: request.agent.Mode.FOREGROUND,
    overwrite: false,
    method: "PUT",
    data: attachments,
    saveas: "./",
    network: request.agent.Network.CELLULAR,
    metered: false,
    roaming: true,
    retry: true,
    redirect: true,
    index: 0,
    begins: 0,
    ends: -1,
    gauge: false,
    precise: false,
    token: "it is a secret"
  };
  let createOnCallback = (progress: request.agent.Progress) => {
    console.info('upload task pause.');
  };
  request.agent.create(getContext(), config).then((task: request.agent.Task) => {
    task.on('pause', createOnCallback);
    console.info(`Succeeded in creating a upload task. result: ${task.tid}`);
    task.start();
  }).catch((err: BusinessError) => {
    console.error(`Failed to create a upload task, Code: ${err.code}, message: ${err.message}`);
  });
  ```

> **NOTE**
>
> For details about how to obtain the context in the example, see [Obtaining the Context of UIAbility](../../application-models/uiability-usage.md#obtaining-the-context-of-uiability).

### on('resume')<sup>11+</sup>

on(event: 'resume', callback: (progress: [Progress](#progress10)) =&gt; void): void

Subscribes to task resume events. This API uses an asynchronous callback to return the result.

**System capability**: SystemCapability.Request.FileTransferAgent

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| event | string | Yes| Type of the event to subscribe to.<br>The value is **'resume'**, indicating task resume.|
| callback | function | Yes| Callback used to return the data structure of the task progress.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 401 | Parameter error. Possible causes: 1. Missing mandatory parameters 2. Incorrect parameter type 3. Parameter verification failed |

**Example**

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

  let attachments: Array<request.agent.FormItem> = [{
    name: "taskOnTest",
    value: {
      filename: "taskOnTest.avi",
      mimeType: "application/octet-stream",
      path: "./taskOnTest.avi",
    }
  }];
  let config: request.agent.Config = {
    action: request.agent.Action.UPLOAD,
    url: 'http://127.0.0.1', // Replace the URL with the HTTP address of the real server.
    title: 'taskOnTest',
    description: 'Sample code for event listening',
    mode: request.agent.Mode.FOREGROUND,
    overwrite: false,
    method: "PUT",
    data: attachments,
    saveas: "./",
    network: request.agent.Network.CELLULAR,
    metered: false,
    roaming: true,
    retry: true,
    redirect: true,
    index: 0,
    begins: 0,
    ends: -1,
    gauge: false,
    precise: false,
    token: "it is a secret"
  };
  let createOnCallback = (progress: request.agent.Progress) => {
    console.info('upload task resume.');
  };
  request.agent.create(getContext(), config).then((task: request.agent.Task) => {
    task.on('resume', createOnCallback);
    console.info(`Succeeded in creating a upload task. result: ${task.tid}`);
    task.start();
  }).catch((err: BusinessError) => {
    console.error(`Failed to create a upload task, Code: ${err.code}, message: ${err.message}`);
  });
  ```

> **NOTE**
>
> For details about how to obtain the context in the example, see [Obtaining the Context of UIAbility](../../application-models/uiability-usage.md#obtaining-the-context-of-uiability).

### on('remove')<sup>11+</sup>

on(event: 'remove', callback: (progress: [Progress](#progress10)) =&gt; void): void

Subscribes to task removal events. This API uses an asynchronous callback to return the result.

**System capability**: SystemCapability.Request.FileTransferAgent

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| event | string | Yes| Type of the event to subscribe to.<br>- **'remove'**: task removal event.|
| callback | function | Yes| Callback used to return the data structure of the task progress.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 401 | Parameter error. Possible causes: 1. Missing mandatory parameters 2. Incorrect parameter type 3. Parameter verification failed |

**Example**

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

  let attachments: Array<request.agent.FormItem> = [{
    name: "taskOnTest",
    value: {
      filename: "taskOnTest.avi",
      mimeType: "application/octet-stream",
      path: "./taskOnTest.avi",
    }
  }];
  let config: request.agent.Config = {
    action: request.agent.Action.UPLOAD,
    url: 'http://127.0.0.1', // Replace the URL with the HTTP address of the real server.
    title: 'taskOnTest',
    description: 'Sample code for event listening',
    mode: request.agent.Mode.FOREGROUND,
    overwrite: false,
    method: "PUT",
    data: attachments,
    saveas: "./",
    network: request.agent.Network.CELLULAR,
    metered: false,
    roaming: true,
    retry: true,
    redirect: true,
    index: 0,
    begins: 0,
    ends: -1,
    gauge: false,
    precise: false,
    token: "it is a secret"
  };
  let createOnCallback = (progress: request.agent.Progress) => {
    console.info('upload task remove.');
  };
  request.agent.create(getContext(), config).then((task: request.agent.Task) => {
    task.on('remove', createOnCallback);
    console.info(`Succeeded in creating a upload task. result: ${task.tid}`);
    task.start();
  }).catch((err: BusinessError) => {
    console.error(`Failed to create a upload task, Code: ${err.code}, message: ${err.message}`);
  });
  ```

> **NOTE**
>
> For details about how to obtain the context in the example, see [Obtaining the Context of UIAbility](../../application-models/uiability-usage.md#obtaining-the-context-of-uiability).

### on('response')<sup>12+</sup>

on(event: 'response', callback: Callback&lt;HttpResponse&gt;): void

Subscribes to task response headers. This API uses an asynchronous callback to return the result.

**Atomic service API**: This API can be used in atomic services since API version 12.

**System capability**: SystemCapability.Request.FileTransferAgent

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| event | string | Yes| Type of the event to subscribe to.<br>The value is **response**, which indicates the task response.|
| callback | function | Yes| Callback used to return the data structure of the task response header.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 401 | Parameter error. Possible causes: 1. Missing mandatory parameters 2. Incorrect parameter type 3. Parameter verification failed |

**Example**

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

  let attachments: Array<request.agent.FormItem> = [{
    name: "taskOnTest",
    value: {
      filename: "taskOnTest.avi",
      mimeType: "application/octet-stream",
      path: "./taskOnTest.avi",
    }
  }];
  let config: request.agent.Config = {
    action: request.agent.Action.UPLOAD,
    url: 'http://127.0.0.1', // Replace the URL with the HTTP address of the real server.
    title: 'taskOnTest',
    description: 'Sample code for event listening',
    mode: request.agent.Mode.FOREGROUND,
    overwrite: false,
    method: "PUT",
    data: attachments,
    saveas: "./",
    network: request.agent.Network.CELLULAR,
    metered: false,
    roaming: true,
    retry: true,
    redirect: true,
    index: 0,
    begins: 0,
    ends: -1,
    gauge: false,
    precise: false,
    token: "it is a secret"
  };
  let createOnCallback = (response: request.agent.HttpResponse) => {
    console.info('upload task response.');
  };
  request.agent.create(getContext(), config).then((task: request.agent.Task) => {
    task.on('response', createOnCallback);
    console.info(`Succeeded in creating a upload task. result: ${task.tid}`);
    task.start();
  }).catch((err: BusinessError) => {
    console.error(`Failed to create a upload task, Code: ${err.code}, message: ${err.message}`);
  });
  ```

> **NOTE**
>
> For details about how to obtain the context in the example, see [Obtaining the Context of UIAbility](../../application-models/uiability-usage.md#obtaining-the-context-of-uiability).

### off('progress')<sup>10+</sup>

off(event: 'progress', callback?: (progress: [Progress](#progress10)) =&gt; void): void

Unsubscribes from task progress events.

**Atomic service API**: This API can be used in atomic services since API version 11.

**System capability**: SystemCapability.Request.FileTransferAgent

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| event | string | Yes| Type of the event to subscribe to.<br>The value is **'progress'**, indicating the task progress.|
| callback | function | No| Callback to unregister. If this parameter is not specified, all callbacks of the current type will be unregistered.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 401 | Parameter error. Possible causes: 1. Missing mandatory parameters 2. Incorrect parameter type 3. Parameter verification failed |

**Example**

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

  let attachments: Array<request.agent.FormItem> = [{
    name: "taskOffTest",
    value: {
      filename: "taskOffTest.avi",
      mimeType: "application/octet-stream",
      path: "./taskOffTest.avi",
    }
  }];
  let config: request.agent.Config = {
    action: request.agent.Action.UPLOAD,
    url: 'http://127.0.0.1', // Replace the URL with the HTTP address of the real server.
    title: 'taskOffTest',
    description: 'Sample code for event listening',
    mode: request.agent.Mode.FOREGROUND,
    overwrite: false,
    method: "PUT",
    data: attachments,
    saveas: "./",
    network: request.agent.Network.CELLULAR,
    metered: false,
    roaming: true,
    retry: true,
    redirect: true,
    index: 0,
    begins: 0,
    ends: -1,
    gauge: false,
    precise: false,
    token: "it is a secret"
  };
  let createOffCallback1 = (progress: request.agent.Progress) => {
    console.info('upload task progress.');
  };
  let createOffCallback2 = (progress: request.agent.Progress) => {
    console.info('upload task progress.');
  };
  request.agent.create(getContext(), config).then((task: request.agent.Task) => {
    task.on('progress', createOffCallback1);
    task.on('progress', createOffCallback2);
    // Unsubscribe from createOffCallback1.
    task.off('progress', createOffCallback1);
    // Unsubscribe from all callbacks of task progress changes.
    task.off('progress');
    console.info(`Succeeded in creating a upload task. result: ${task.tid}`);
    task.start();
  }).catch((err: BusinessError) => {
    console.error(`Failed to create a upload task, Code: ${err.code}, message: ${err.message}`);
  });
  ```

> **NOTE**
>
> For details about how to obtain the context in the example, see [Obtaining the Context of UIAbility](../../application-models/uiability-usage.md#obtaining-the-context-of-uiability).

### off('completed')<sup>10+</sup>

off(event: 'completed', callback?: (progress: [Progress](#progress10)) =&gt; void): void

Unsubscribes from task completion events.

**Atomic service API**: This API can be used in atomic services since API version 11.

**System capability**: SystemCapability.Request.FileTransferAgent

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| event | string | Yes| Type of the event to subscribe to.<br>The value is **'completed'**, indicating task completion.|
| callback | function | No| Callback to unregister. If this parameter is not specified, all callbacks of the current type will be unregistered.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 401 | Parameter error. Possible causes: 1. Missing mandatory parameters 2. Incorrect parameter type 3. Parameter verification failed |

**Example**

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

  let attachments: Array<request.agent.FormItem> = [{
    name: "taskOffTest",
    value: {
      filename: "taskOffTest.avi",
      mimeType: "application/octet-stream",
      path: "./taskOffTest.avi",
    }
  }];
  let config: request.agent.Config = {
    action: request.agent.Action.UPLOAD,
    url: 'http://127.0.0.1', // Replace the URL with the HTTP address of the real server.
    title: 'taskOffTest',
    description: 'Sample code for event listening',
    mode: request.agent.Mode.FOREGROUND,
    overwrite: false,
    method: "PUT",
    data: attachments,
    saveas: "./",
    network: request.agent.Network.CELLULAR,
    metered: false,
    roaming: true,
    retry: true,
    redirect: true,
    index: 0,
    begins: 0,
    ends: -1,
    gauge: false,
    precise: false,
    token: "it is a secret"
  };
  let createOffCallback1 = (progress: request.agent.Progress) => {
    console.info('upload task completed.');
  };
  let createOffCallback2 = (progress: request.agent.Progress) => {
    console.info('upload task completed.');
  };
  request.agent.create(getContext(), config).then((task: request.agent.Task) => {
    task.on('completed', createOffCallback1);
    task.on('completed', createOffCallback2);
    // Unsubscribe from createOffCallback1.
    task.off('completed', createOffCallback1);
    // Unsubscribe from all callbacks of the task completion events.
    task.off('completed');
    console.info(`Succeeded in creating a upload task. result: ${task.tid}`);
    task.start();
  }).catch((err: BusinessError) => {
    console.error(`Failed to create a upload task, Code: ${err.code}, message: ${err.message}`);
  });
  ```

> **NOTE**
>
> For details about how to obtain the context in the example, see [Obtaining the Context of UIAbility](../../application-models/uiability-usage.md#obtaining-the-context-of-uiability).

### off('failed')<sup>10+</sup>

off(event: 'failed', callback?: (progress: [Progress](#progress10)) =&gt; void): void

Unsubscribes from task failure events.

**Atomic service API**: This API can be used in atomic services since API version 11.

**System capability**: SystemCapability.Request.FileTransferAgent

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| event | string | Yes| Type of the event to subscribe to.<br>The value is **'failed'**, indicating task failure.|
| callback | function | No| Callback to unregister. If this parameter is not specified, all callbacks of the current type will be unregistered.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 401 | Parameter error. Possible causes: 1. Missing mandatory parameters 2. Incorrect parameter type 3. Parameter verification failed |

**Example**

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

  let attachments: Array<request.agent.FormItem> = [{
    name: "taskOffTest",
    value: {
      filename: "taskOffTest.avi",
      mimeType: "application/octet-stream",
      path: "./taskOffTest.avi",
    }
  }];
  let config: request.agent.Config = {
    action: request.agent.Action.UPLOAD,
    url: 'http://127.0.0.1', // Replace the URL with the HTTP address of the real server.
    title: 'taskOffTest',
    description: 'Sample code for event listening',
    mode: request.agent.Mode.FOREGROUND,
    overwrite: false,
    method: "PUT",
    data: attachments,
    saveas: "./",
    network: request.agent.Network.CELLULAR,
    metered: false,
    roaming: true,
    retry: true,
    redirect: true,
    index: 0,
    begins: 0,
    ends: -1,
    gauge: false,
    precise: false,
    token: "it is a secret"
  };
  let createOffCallback1 = (progress: request.agent.Progress) => {
    console.info('upload task failed.');
  };
  let createOffCallback2 = (progress: request.agent.Progress) => {
    console.info('upload task failed.');
  };
  request.agent.create(getContext(), config).then((task: request.agent.Task) => {
    task.on('failed', createOffCallback1);
    task.on('failed', createOffCallback2);
    // Unsubscribe from createOffCallback1.
    task.off('failed', createOffCallback1);
    // Unsubscribe from all callbacks of the task failure events.
    task.off('failed');
    console.info(`Succeeded in creating a upload task. result: ${task.tid}`);
    task.start();
  }).catch((err: BusinessError) => {
    console.error(`Failed to create a upload task, Code: ${err.code}, message: ${err.message}`);
  });
  ```

> **NOTE**
>
> For details about how to obtain the context in the example, see [Obtaining the Context of UIAbility](../../application-models/uiability-usage.md#obtaining-the-context-of-uiability).

### off('pause')<sup>11+</sup>

off(event: 'pause', callback?: (progress: [Progress](#progress10)) =&gt; void): void

Unsubscribes from the foreground task pause event.

**System capability**: SystemCapability.Request.FileTransferAgent

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| event | string | Yes| Type of the event to subscribe to.<br>- **'pause'**: task pause event.|
| callback | function | No| Callback to unregister. If this parameter is not specified, all callbacks of the current type will be unregistered.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 401 | Parameter error. Possible causes: 1. Missing mandatory parameters 2. Incorrect parameter type 3. Parameter verification failed |

**Example**

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

  let attachments: Array<request.agent.FormItem> = [{
    name: "taskOffTest",
    value: {
      filename: "taskOffTest.avi",
      mimeType: "application/octet-stream",
      path: "./taskOffTest.avi",
    }
  }];
  let config: request.agent.Config = {
    action: request.agent.Action.UPLOAD,
    url: 'http://127.0.0.1', // Replace the URL with the HTTP address of the real server.
    title: 'taskOffTest',
    description: 'Sample code for event listening',
    mode: request.agent.Mode.FOREGROUND,
    overwrite: false,
    method: "PUT",
    data: attachments,
    saveas: "./",
    network: request.agent.Network.CELLULAR,
    metered: false,
    roaming: true,
    retry: true,
    redirect: true,
    index: 0,
    begins: 0,
    ends: -1,
    gauge: false,
    precise: false,
    token: "it is a secret"
  };
  let createOffCallback1 = (progress: request.agent.Progress) => {
    console.info('upload task pause.');
  };
  let createOffCallback2 = (progress: request.agent.Progress) => {
    console.info('upload task pause.');
  };
  request.agent.create(getContext(), config).then((task: request.agent.Task) => {
    task.on('pause', createOffCallback1);
    task.on('pause', createOffCallback2);
    // Unsubscribe from createOffCallback1.
    task.off('pause', createOffCallback1);
    // Unsubscribe from all callbacks of the foreground task pause event.
    task.off('pause');
    console.info(`Succeeded in creating a upload task. result: ${task.tid}`);
    task.start();
  }).catch((err: BusinessError) => {
    console.error(`Failed to create a upload task, Code: ${err.code}, message: ${err.message}`);
  });
  ```

> **NOTE**
>
> For details about how to obtain the context in the example, see [Obtaining the Context of UIAbility](../../application-models/uiability-usage.md#obtaining-the-context-of-uiability).

### off('resume')<sup>11+</sup>

off(event: 'resume', callback?: (progress: [Progress](#progress10)) =&gt; void): void

Unsubscribes from the foreground task resume event.

**System capability**: SystemCapability.Request.FileTransferAgent

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| event | string | Yes| Type of the event to subscribe to.<br>The value is **'resume'**, indicating task resume.|
| callback | function | No| Callback to unregister. If this parameter is not specified, all callbacks of the current type will be unregistered.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 401 | Parameter error. Possible causes: 1. Missing mandatory parameters 2. Incorrect parameter type 3. Parameter verification failed |

**Example**

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

  let attachments: Array<request.agent.FormItem> = [{
    name: "taskOffTest",
    value: {
      filename: "taskOffTest.avi",
      mimeType: "application/octet-stream",
      path: "./taskOffTest.avi",
    }
  }];
  let config: request.agent.Config = {
    action: request.agent.Action.UPLOAD,
    url: 'http://127.0.0.1', // Replace the URL with the HTTP address of the real server.
    title: 'taskOffTest',
    description: 'Sample code for event listening',
    mode: request.agent.Mode.FOREGROUND,
    overwrite: false,
    method: "PUT",
    data: attachments,
    saveas: "./",
    network: request.agent.Network.CELLULAR,
    metered: false,
    roaming: true,
    retry: true,
    redirect: true,
    index: 0,
    begins: 0,
    ends: -1,
    gauge: false,
    precise: false,
    token: "it is a secret"
  };
  let createOffCallback1 = (progress: request.agent.Progress) => {
    console.info('upload task resume.');
  };
  let createOffCallback2 = (progress: request.agent.Progress) => {
    console.info('upload task resume.');
  };
  request.agent.create(getContext(), config).then((task: request.agent.Task) => {
    task.on('resume', createOffCallback1);
    task.on('resume', createOffCallback2);
    // Unsubscribe from createOffCallback1.
    task.off('resume', createOffCallback1);
    // Unsubscribe from all callbacks of the foreground task resume event.
    task.off('resume');
    console.info(`Succeeded in creating a upload task. result: ${task.tid}`);
    task.start();
  }).catch((err: BusinessError) => {
    console.error(`Failed to create a upload task, Code: ${err.code}, message: ${err.message}`);
  });
  ```

> **NOTE**
>
> For details about how to obtain the context in the example, see [Obtaining the Context of UIAbility](../../application-models/uiability-usage.md#obtaining-the-context-of-uiability).

### off('remove')<sup>11+</sup>

off(event: 'remove', callback?: (progress: [Progress](#progress10)) =&gt; void): void

Unsubscribes from the task removal event.

**System capability**: SystemCapability.Request.FileTransferAgent

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| event | string | Yes| Type of the event to subscribe to.<br>- **'remove'**: task removal event.|
| callback | function | No| Callback to unregister. If this parameter is not specified, all callbacks of the current type will be unregistered.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 401 | Parameter error. Possible causes: 1. Missing mandatory parameters 2. Incorrect parameter type 3. Parameter verification failed |

**Example**

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

  let attachments: Array<request.agent.FormItem> = [{
    name: "taskOffTest",
    value: {
      filename: "taskOffTest.avi",
      mimeType: "application/octet-stream",
      path: "./taskOffTest.avi",
    }
  }];
  let config: request.agent.Config = {
    action: request.agent.Action.UPLOAD,
    url: 'http://127.0.0.1', // Replace the URL with the HTTP address of the real server.
    title: 'taskOffTest',
    description: 'Sample code for event listening',
    mode: request.agent.Mode.FOREGROUND,
    overwrite: false,
    method: "PUT",
    data: attachments,
    saveas: "./",
    network: request.agent.Network.CELLULAR,
    metered: false,
    roaming: true,
    retry: true,
    redirect: true,
    index: 0,
    begins: 0,
    ends: -1,
    gauge: false,
    precise: false,
    token: "it is a secret"
  };
  let createOffCallback1 = (progress: request.agent.Progress) => {
    console.info('upload task remove.');
  };
  let createOffCallback2 = (progress: request.agent.Progress) => {
    console.info('upload task remove.');
  };
  request.agent.create(getContext(), config).then((task: request.agent.Task) => {
    task.on('remove', createOffCallback1);
    task.on('remove', createOffCallback2);
    // Unsubscribe from createOffCallback1.
    task.off('remove', createOffCallback1);
    // Unsubscribe from all callbacks of the task removal event.
    task.off('remove');
    console.info(`Succeeded in creating a upload task. result: ${task.tid}`);
    task.start();
  }).catch((err: BusinessError) => {
    console.error(`Failed to create a upload task, Code: ${err.code}, message: ${err.message}`);
  });
  ```

> **NOTE**
>
> For details about how to obtain the context in the example, see [Obtaining the Context of UIAbility](../../application-models/uiability-usage.md#obtaining-the-context-of-uiability).

### off('response')<sup>12+</sup>

off(event: 'response', callback?: Callback&lt;HttpResponse&gt;): void

Unsubscribes from task response headers.

**Atomic service API**: This API can be used in atomic services since API version 12.

**System capability**: SystemCapability.Request.FileTransferAgent

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| event | string | Yes| Type of the event to subscribe to.<br>The value is **response**, which indicates the task response.|
| callback | function | No| Callback to unregister. If this parameter is not specified, all callbacks of the current type will be unregistered.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 401 | Parameter error. Possible causes: 1. Missing mandatory parameters 2. Incorrect parameter type 3. Parameter verification failed |

**Example**

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

  let attachments: Array<request.agent.FormItem> = [{
    name: "taskOffTest",
    value: {
      filename: "taskOffTest.avi",
      mimeType: "application/octet-stream",
      path: "./taskOffTest.avi",
    }
  }];
  let config: request.agent.Config = {
    action: request.agent.Action.UPLOAD,
    url: 'http://127.0.0.1', // Replace the URL with the HTTP address of the real server.
    title: 'taskOffTest',
    description: 'Sample code for event listening',
    mode: request.agent.Mode.FOREGROUND,
    overwrite: false,
    method: "PUT",
    data: attachments,
    saveas: "./",
    network: request.agent.Network.CELLULAR,
    metered: false,
    roaming: true,
    retry: true,
    redirect: true,
    index: 0,
    begins: 0,
    ends: -1,
    gauge: false,
    precise: false,
    token: "it is a secret"
  };
  let createOffCallback1 = (progress: request.agent.HttpResponse) => {
    console.info('upload task response.');
  };
  let createOffCallback2 = (progress: request.agent.HttpResponse) => {
    console.info('upload task response.');
  };
  request.agent.create(getContext(), config).then((task: request.agent.Task) => {
    task.on('response', createOffCallback1);
    task.on('response', createOffCallback2);
    // Unsubscribe from createOffCallback1.
    task.off('response', createOffCallback1);
    // Unsubscribe from all callbacks of the task removal event.
    task.off('response');
    console.info(`Succeeded in creating a upload task. result: ${task.tid}`);
    task.start();
  }).catch((err: BusinessError) => {
    console.error(`Failed to create a upload task, Code: ${err.code}, message: ${err.message}`);
  });
  ```

> **NOTE**
>
> For details about how to obtain the context in the example, see [Obtaining the Context of UIAbility](../../application-models/uiability-usage.md#obtaining-the-context-of-uiability).

### start<sup>10+</sup>

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

Tasks in the following states can be started:
1. Task created by **request.agent.create**.
2. Download tasks that are created by **request.agent.create** but have failed or paused.

**Required permissions**: ohos.permission.INTERNET

**Atomic service API**: This API can be used in atomic services since API version 11.

**System capability**: SystemCapability.Request.FileTransferAgent

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| callback | function | Yes| Callback used to return the result. If the operation is successful, **err** is **undefined**. Otherwise, **err** is an error object.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 201 | Permission denied. |
| 13400003 | task service ability error. |
| 21900007 | task state error. |

**Example**

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

  let config: request.agent.Config = {
    action: request.agent.Action.DOWNLOAD,
    url: 'http://127.0.0.1', // Replace the URL with the HTTP address of the real server.
    title: 'taskStartTest',
    description: 'Sample code for start the download task',
    mode: request.agent.Mode.BACKGROUND,
    overwrite: false,
    method: "GET",
    data: "",
    saveas: "./",
    network: request.agent.Network.CELLULAR,
    metered: false,
    roaming: true,
    retry: true,
    redirect: true,
    index: 0,
    begins: 0,
    ends: -1,
    gauge: false,
    precise: false,
    token: "it is a secret"
  };
  request.agent.create(getContext(), config).then((task: request.agent.Task) => {
    task.start((err: BusinessError) => {
      if (err) {
        console.error(`Failed to start the download task, Code: ${err.code}, message: ${err.message}`);
        return;
      }
      console.info(`Succeeded in starting a download task.`);
    });
    console.info(`Succeeded in creating a download task. result: ${task.tid}`);
  }).catch((err: BusinessError) => {
    console.error(`Failed to create a download task, Code: ${err.code}, message: ${err.message}`);
  });
  ```

> **NOTE**
>
> For details about how to obtain the context in the example, see [Obtaining the Context of UIAbility](../../application-models/uiability-usage.md#obtaining-the-context-of-uiability).

### start<sup>10+</sup>

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

Tasks in the following states can be started:
1. Task created by **request.agent.create**.
2. Download tasks that are created by **request.agent.create** but have failed or paused.

**Required permissions**: ohos.permission.INTERNET

**Atomic service API**: This API can be used in atomic services since API version 11.

**System capability**: SystemCapability.Request.FileTransferAgent

**Return value**

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

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 201 | Permission denied. |
| 13400003 | task service ability error. |
| 21900007 | task state error. |

**Example**

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

  let config: request.agent.Config = {
    action: request.agent.Action.DOWNLOAD,
    url: 'http://127.0.0.1', // Replace the URL with the HTTP address of the real server.
    title: 'taskStartTest',
    description: 'Sample code for start the download task',
    mode: request.agent.Mode.BACKGROUND,
    overwrite: false,
    method: "GET",
    data: "",
    saveas: "./",
    network: request.agent.Network.CELLULAR,
    metered: false,
    roaming: true,
    retry: true,
    redirect: true,
    index: 0,
    begins: 0,
    ends: -1,
    gauge: false,
    precise: false,
    token: "it is a secret"
  };
  request.agent.create(getContext(), config).then((task: request.agent.Task) => {
    task.start().then(() => {
      console.info(`Succeeded in starting a download task.`);
    }).catch((err: BusinessError) => {
      console.error(`Failed to start the download task, Code: ${err.code}, message: ${err.message}`);
    });
    console.info(`Succeeded in creating a download task. result: ${task.tid}`);
  }).catch((err: BusinessError) => {
    console.error(`Failed to create a download task, Code: ${err.code}, message: ${err.message}`);
  });
  ```

> **NOTE**
>
> For details about how to obtain the context in the example, see [Obtaining the Context of UIAbility](../../application-models/uiability-usage.md#obtaining-the-context-of-uiability).

### pause<sup>10+</sup>

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

Pauses a task that is waiting, running, or retrying. This API uses an asynchronous callback to return the result.

**System capability**: SystemCapability.Request.FileTransferAgent

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| callback | function | Yes| Callback used to return the result. If the operation is successful, **err** is **undefined**. Otherwise, **err** is an error object.|

**Error codes**

For details about the error codes, see [Upload and Download Error Codes](errorcode-request.md).

| ID| Error Message|
| -------- | -------- |
| 13400003 | task service ability error. |
| 21900007 | task state error. |

**Example**

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

  let config: request.agent.Config = {
    action: request.agent.Action.DOWNLOAD,
    url: 'http://127.0.0.1', // Replace the URL with the HTTP address of the real server.
    title: 'taskPauseTest',
    description: 'Sample code for pause the download task',
    mode: request.agent.Mode.BACKGROUND,
    overwrite: false,
    method: "GET",
    data: "",
    saveas: "./",
    network: request.agent.Network.CELLULAR,
    metered: false,
    roaming: true,
    retry: true,
    redirect: true,
    index: 0,
    begins: 0,
    ends: -1,
    gauge: false,
    precise: false,
    token: "it is a secret"
  };
  request.agent.create(getContext(), config).then((task: request.agent.Task) => {
    task.start();
    for(let t = Date.now(); Date.now() - t <= 1000;); // To prevent asynchronous out-of-order, wait for 1 second before performing the next operation.
    task.pause((err: BusinessError) => {
      if (err) {
        console.error(`Failed to pause the download task, Code: ${err.code}, message: ${err.message}`);
        return;
      }
      console.info(`Succeeded in pausing a download task. `);
    });
    console.info(`Succeeded in creating a download task. result: ${task.tid}`);
  }).catch((err: BusinessError) => {
    console.error(`Failed to create a download task, Code: ${err.code}, message: ${err.message}`);
  });
  ```

### pause<sup>10+</sup>

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

Pauses a task that is waiting, running, or retrying. This API uses a promise to return the result.

**System capability**: SystemCapability.Request.FileTransferAgent

**Return value**

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

**Error codes**

For details about the error codes, see [Upload and Download Error Codes](errorcode-request.md).

| ID| Error Message|
| -------- | -------- |
| 13400003 | task service ability error. |
| 21900007 | task state error. |

**Example**

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

  let config: request.agent.Config = {
    action: request.agent.Action.DOWNLOAD,
    url: 'http://127.0.0.1', // Replace the URL with the HTTP address of the real server.
    title: 'taskPauseTest',
    description: 'Sample code for pause the download task',
    mode: request.agent.Mode.BACKGROUND,
    overwrite: false,
    method: "GET",
    data: "",
    saveas: "./",
    network: request.agent.Network.CELLULAR,
    metered: false,
    roaming: true,
    retry: true,
    redirect: true,
    index: 0,
    begins: 0,
    ends: -1,
    gauge: false,
    precise: false,
    token: "it is a secret"
  };
  request.agent.create(getContext(), config).then((task: request.agent.Task) => {
    task.start();
    for(let t = Date.now(); Date.now() - t <= 1000;); // To prevent asynchronous out-of-order, wait for 1 second before performing the next operation.
    task.pause().then(() => {
      console.info(`Succeeded in pausing a download task. `);
    }).catch((err: BusinessError) => {
      console.error(`Failed to pause the download task, Code: ${err.code}, message: ${err.message}`);
    });
    console.info(`Succeeded in creating a download task. result: ${task.tid}`);
  }).catch((err: BusinessError) => {
    console.error(`Failed to create a download task, Code: ${err.code}, message: ${err.message}`);
  });
  ```

### resume<sup>10+</sup>

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

Resumes a paused task. This API uses an asynchronous callback to return the result.

**Required permissions**: ohos.permission.INTERNET

**System capability**: SystemCapability.Request.FileTransferAgent

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| callback | function | Yes| Callback used to return the result. If the operation is successful, **err** is **undefined**. Otherwise, **err** is an error object.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 201 | Permission denied. |
| 13400003 | task service ability error. |
| 21900007 | task state error. |

**Example**

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

  let config: request.agent.Config = {
    action: request.agent.Action.DOWNLOAD,
    url: 'http://127.0.0.1', // Replace the URL with the HTTP address of the real server.
    title: 'taskResumeTest',
    description: 'Sample code for resume the download task',
    mode: request.agent.Mode.BACKGROUND,
    overwrite: false,
    method: "GET",
    data: "",
    saveas: "./",
    network: request.agent.Network.CELLULAR,
    metered: false,
    roaming: true,
    retry: true,
    redirect: true,
    index: 0,
    begins: 0,
    ends: -1,
    gauge: false,
    precise: false,
    token: "it is a secret"
  };
  request.agent.create(getContext(), config).then((task: request.agent.Task) => {
    task.start();
    for(let t = Date.now(); Date.now() - t <= 1000;); // To prevent asynchronous out-of-order, wait for 1 second before performing the next operation.
    task.pause();
    for(let t = Date.now(); Date.now() - t <= 1000;); // To prevent asynchronous out-of-order, wait for 1 second before performing the next operation.
    task.resume((err: BusinessError) => {
      if (err) {
        console.error(`Failed to resume the download task, Code: ${err.code}, message: ${err.message}`);
        return;
      }
      console.info(`Succeeded in resuming a download task. `);
    });
    console.info(`Succeeded in creating a download task. result: ${task.tid}`);
  }).catch((err: BusinessError) => {
    console.error(`Failed to create a download task, Code: ${err.code}, message: ${err.message}`);
  });
  ```

### resume<sup>10+</sup>

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

Resumes a paused task. This API uses a promise to return the result.

**Required permissions**: ohos.permission.INTERNET

**System capability**: SystemCapability.Request.FileTransferAgent

**Return value**

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

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 201 | Permission denied. |
| 13400003 | task service ability error. |
| 21900007 | task state error. |

**Example**

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

  let config: request.agent.Config = {
    action: request.agent.Action.DOWNLOAD,
    url: 'http://127.0.0.1', // Replace the URL with the HTTP address of the real server.
    title: 'taskResumeTest',
    description: 'Sample code for resume the download task',
    mode: request.agent.Mode.BACKGROUND,
    overwrite: false,
    method: "GET",
    data: "",
    saveas: "./",
    network: request.agent.Network.CELLULAR,
    metered: false,
    roaming: true,
    retry: true,
    redirect: true,
    index: 0,
    begins: 0,
    ends: -1,
    gauge: false,
    precise: false,
    token: "it is a secret"
  };
  request.agent.create(getContext(), config).then((task: request.agent.Task) => {
    task.start();
    for(let t = Date.now(); Date.now() - t <= 1000;); // To prevent asynchronous out-of-order, wait for 1 second before performing the next operation.
    task.pause();
    for(let t = Date.now(); Date.now() - t <= 1000;); // To prevent asynchronous out-of-order, wait for 1 second before performing the next operation.
    task.resume().then(() => {
      console.info(`Succeeded in resuming a download task. `);
    }).catch((err: BusinessError) => {
      console.error(`Failed to resume the download task, Code: ${err.code}, message: ${err.message}`);
    });
    console.info(`Succeeded in creating a download task. result: ${task.tid}`);
  }).catch((err: BusinessError) => {
    console.error(`Failed to create a download task, Code: ${err.code}, message: ${err.message}`);
  });
  ```

### stop<sup>10+</sup>

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

Stops this task. This API can be used to stop a running, waiting, or retrying task. This API uses an asynchronous callback to return the result.

**Atomic service API**: This API can be used in atomic services since API version 11.

**System capability**: SystemCapability.Request.FileTransferAgent

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| callback | function | Yes| Callback used to return the result. If the operation is successful, **err** is **undefined**. Otherwise, **err** is an error object.|

**Error codes**

For details about the error codes, see [Upload and Download Error Codes](errorcode-request.md).

| ID| Error Message|
| -------- | -------- |
| 13400003 | task service ability error. |
| 21900007 | task state error. |

**Example**

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

  let config: request.agent.Config = {
    action: request.agent.Action.DOWNLOAD,
    url: 'http://127.0.0.1', // Replace the URL with the HTTP address of the real server.
    title: 'taskStopTest',
    description: 'Sample code for stop the download task',
    mode: request.agent.Mode.BACKGROUND,
    overwrite: false,
    method: "GET",
    data: "",
    saveas: "./",
    network: request.agent.Network.CELLULAR,
    metered: false,
    roaming: true,
    retry: true,
    redirect: true,
    index: 0,
    begins: 0,
    ends: -1,
    gauge: false,
    precise: false,
    token: "it is a secret"
  };
  request.agent.create(getContext(), config).then((task: request.agent.Task) => {
    task.start();
    for(let t = Date.now(); Date.now() - t <= 1000;); // To prevent asynchronous out-of-order, wait for 1 second before performing the next operation.
    task.stop((err: BusinessError) => {
      if (err) {
        console.error(`Failed to stop the download task, Code: ${err.code}, message: ${err.message}`);
        return;
      }
      console.info(`Succeeded in stopping a download task. `);
    });
    console.info(`Succeeded in creating a download task. result: ${task.tid}`);
  }).catch((err: BusinessError) => {
    console.error(`Failed to create a download task, Code: ${err.code}, message: ${err.message}`);
  });
  ```


### stop<sup>10+</sup>

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

Stops this task. This API can be used to stop a running, waiting, or retrying task. This API uses a promise to return the result.

**Atomic service API**: This API can be used in atomic services since API version 11.

**System capability**: SystemCapability.Request.FileTransferAgent

**Return value**

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

**Error codes**

For details about the error codes, see [Upload and Download Error Codes](errorcode-request.md).

| ID| Error Message|
| -------- | -------- |
| 13400003 | task service ability error. |
| 21900007 | task state error. |

**Example**

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

  let config: request.agent.Config = {
    action: request.agent.Action.DOWNLOAD,
    url: 'http://127.0.0.1', // Replace the URL with the HTTP address of the real server.
    title: 'taskStopTest',
    description: 'Sample code for stop the download task',
    mode: request.agent.Mode.BACKGROUND,
    overwrite: false,
    method: "GET",
    data: "",
    saveas: "./",
    network: request.agent.Network.CELLULAR,
    metered: false,
    roaming: true,
    retry: true,
    redirect: true,
    index: 0,
    begins: 0,
    ends: -1,
    gauge: false,
    precise: false,
    token: "it is a secret"
  };
  request.agent.create(getContext(), config).then((task: request.agent.Task) => {
    task.start();
    for(let t = Date.now(); Date.now() - t <= 1000;); // To prevent asynchronous out-of-order, wait for 1 second before performing the next operation.
    task.stop().then(() => {
      console.info(`Succeeded in stopping a download task. `);
    }).catch((err: BusinessError) => {
      console.error(`Failed to stop the download task, Code: ${err.code}, message: ${err.message}`);
    });
    console.info(`Succeeded in creating a download task. result: ${task.tid}`);
  }).catch((err: BusinessError) => {
    console.error(`Failed to create a download task, Code: ${err.code}, message: ${err.message}`);
  });
  ```

## request.agent.create<sup>10+</sup>

create(context: BaseContext, config: Config, callback: AsyncCallback&lt;Task&gt;): void

Creates an upload or download task and adds it to the queue. This API uses an asynchronous callback to return a result. HTTP is supported.


**Required permissions**: ohos.permission.INTERNET

**Atomic service API**: This API can be used in atomic services since API version 11.

**System capability**: SystemCapability.Request.FileTransferAgent

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| config | [Config](#config10) | Yes| Task configuration.|
| context | [BaseContext](../apis-ability-kit/js-apis-inner-application-baseContext.md) | Yes| Application-based context.|
| callback | AsyncCallback&lt;[Task](#task10)&gt; | Yes| Callback used to return the result. If the operation is successful, **err** is **undefined** and **data** is the **Task** object obtained. Otherwise, **err** is an error object.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 201 | permission denied. |
| 401 | parameter error. Possible causes: 1. Missing mandatory parameters 2. Incorrect parameter type 3. Parameter verification failed |
| 13400001 | file operation error. |
| 13400003 | task service ability error. |
| 21900004 | the application task queue is full. |
| 21900005 | task mode error. |

**Example**

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

  let attachments: Array<request.agent.FormItem> = [{
    name: "createTest",
    value: {
      filename: "createTest.avi",
      mimeType: "application/octet-stream",
      path: "./createTest.avi",
    }
  }];
  let config: request.agent.Config = {
    action: request.agent.Action.UPLOAD,
    url: 'http://127.0.0.1', // Replace the URL with the HTTP address of the real server.
    title: 'createTest',
    description: 'Sample code for create task',
    mode: request.agent.Mode.BACKGROUND,
    overwrite: false,
    method: "PUT",
    data: attachments,
    saveas: "./",
    network: request.agent.Network.CELLULAR,
    metered: false,
    roaming: true,
    retry: true,
    redirect: true,
    index: 0,
    begins: 0,
    ends: -1,
    gauge: false,
    precise: false,
    token: "it is a secret"
  };
  request.agent.create(getContext(), config, async (err: BusinessError, task: request.agent.Task) => {
    if (err) {
      console.error(`Failed to create a download task, Code: ${err.code}, message: ${err.message}`);
      return;
    }
    console.info(`Succeeded in creating a download task. result: ${task.config}`);
    await task.start();
    // You need to manually call remove() to end the lifecycle of the task object.
    request.agent.remove(task.tid);
  });
  ```

> **NOTE**
>
> For details about how to obtain the context in the example, see [Obtaining the Context of UIAbility](../../application-models/uiability-usage.md#obtaining-the-context-of-uiability).

## request.agent.create<sup>10+</sup>

create(context: BaseContext, config: Config): Promise&lt;Task&gt;

Creates an upload or download task and adds it to the queue. This API uses a promise to return the result. HTTP is supported.


**Required permissions**: ohos.permission.INTERNET

**Atomic service API**: This API can be used in atomic services since API version 11.

**System capability**: SystemCapability.Request.FileTransferAgent

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| context | [BaseContext](../apis-ability-kit/js-apis-inner-application-baseContext.md) | Yes| Application-based context.|
| config | [Config](#config10) | Yes| Task configuration.|

**Return value**

| Type               | Description                     |
| ------------------- | ------------------------- |
| Promise&lt;[Task](#task10)&gt; | Promise used to return the configuration about the created task.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 201 | permission denied. |
| 401 | parameter error. Possible causes: 1. Missing mandatory parameters 2. Incorrect parameter type 3. Parameter verification failed |
| 13400001 | file operation error. |
| 13400003 | task service ability error. |
| 21900004 | the application task queue is full. |
| 21900005 | task mode error. |

**Example**

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

  let attachments: Array<request.agent.FormItem> = [{
    name: "createTest",
    value: {
      filename: "createTest.avi",
      mimeType: "application/octet-stream",
      path: "./createTest.avi",
    }
  }];
  let config: request.agent.Config = {
    action: request.agent.Action.UPLOAD,
    url: 'http://127.0.0.1', // Replace the URL with the HTTP address of the real server.
    title: 'createTest',
    description: 'Sample code for create task',
    mode: request.agent.Mode.BACKGROUND,
    overwrite: false,
    method: "PUT",
    data: attachments,
    saveas: "./",
    network: request.agent.Network.CELLULAR,
    metered: false,
    roaming: true,
    retry: true,
    redirect: true,
    index: 0,
    begins: 0,
    ends: -1,
    gauge: false,
    precise: false,
    token: "it is a secret"
  };
  request.agent.create(getContext(), config).then(async (task: request.agent.Task) => {
    console.info(`Succeeded in creating a download task. result: ${task.config}`);
    await task.start();
    // You need to manually call remove() to end the lifecycle of the task object.
    request.agent.remove(task.tid);
  }).catch((err: BusinessError) => {
    console.error(`Failed to create a download task, Code: ${err.code}, message: ${err.message}`);
  });
  ```

> **NOTE**
>
> For details about how to obtain the context in the example, see [Obtaining the Context of UIAbility](../../application-models/uiability-usage.md#obtaining-the-context-of-uiability).

## request.agent.getTask<sup>11+</sup>

getTask(context: BaseContext, id: string, token?: string): Promise&lt;Task&gt;

Obtains task information based on the task ID. This API uses a promise to return the result.

**System capability**: SystemCapability.Request.FileTransferAgent

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| context | [BaseContext](../apis-ability-kit/js-apis-inner-application-baseContext.md) | Yes| Application-based context.|
| id | string | Yes| Task ID.|
| token | string | No| Token for task query.|

**Return value**

| Type               | Description                     |
| ------------------- | ------------------------- |
| Promise&lt;[Task](#task10)&gt; | Promise used to return the configuration about the created task.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 401 | parameter error. Possible causes: 1. Missing mandatory parameters 2. Incorrect parameter type 3. Parameter verification failed |
| 13400003 | task service ability error. |
| 21900006 | task not found. |

**Example**

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

  request.agent.getTask(getContext(), "123456").then((task: request.agent.Task) => {
    console.info(`Succeeded in querying a task. result: ${task.tid}`);
  }).catch((err: BusinessError) => {
    console.error(`Failed to query a task, Code: ${err.code}, message: ${err.message}`);
  });
  ```

## request.agent.remove<sup>10+</sup>

remove(id: string, callback: AsyncCallback&lt;void&gt;): void

Removes a specified task of the invoker. If the task is being executed, the task is forced to stop. This API uses an asynchronous callback to return the result. After this API is called, the **task** object and its callback function are released.

**Atomic service API**: This API can be used in atomic services since API version 11.

**System capability**: SystemCapability.Request.FileTransferAgent

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| id | string | Yes| Task ID.|
| callback | AsyncCallback&lt;void&gt; | Yes| Callback used to return the result. If the operation is successful, **err** is **undefined**. Otherwise, **err** is an error object.|

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 401 | parameter error. Possible causes: 1. Missing mandatory parameters 2. Incorrect parameter type |
| 13400003 | task service ability error. |
| 21900006 | task not found. |

**Example**

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

  request.agent.remove("123456", (err: BusinessError) => {
    if (err) {
      console.error(`Failed to remove a download task, Code: ${err.code}, message: ${err.message}`);
      return;
    }
    console.info(`Succeeded in creating a download task.`);
  });
  ```


## request.agent.remove<sup>10+</sup>

remove(id: string): Promise&lt;void&gt;

Removes a specified task of the invoker. If the task is being executed, the task is forced to stop. This API uses a promise to return the result. After this API is called, the **task** object and its callback function are released.

**Atomic service API**: This API can be used in atomic services since API version 11.

**System capability**: SystemCapability.Request.FileTransferAgent

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| id | string | Yes| Task ID.|

**Return value**

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

**Error codes**

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

| ID| Error Message|
| -------- | -------- |
| 401 | parameter error. Possible causes: 1. Missing mandatory parameters 2. Incorrect parameter type |
| 13400003 | task service ability error. |
| 21900006 | task not found. |

**Example**

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

  request.agent.remove("123456").then(() => {
    console.info(`Succeeded in removing a download task. `);
  }).catch((err: BusinessError) => {
    console.error(`Failed to remove a download task, Code: ${err.code}, message: ${err.message}`);
  });
  ```


## request.agent.show<sup>10+</sup>

show(id: string, callback: AsyncCallback&lt;TaskInfo&gt;): void

Queries a task details based on the task ID. This API uses an asynchronous callback to return the result.

**System capability**: SystemCapability.Request.FileTransferAgent

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| id | string | Yes| Task ID.|
| callback | AsyncCallback&lt;[TaskInfo](#taskinfo10)&gt; | Yes| Callback used to return the result. If the operation is successful, **err** is **undefined** and **data** is the **TaskInfo** object obtained. Otherwise, **err** is an error object.|

**Error codes**
For details about the error codes, see [Upload and Download Error Codes](errorcode-request.md) and [Universal Error Codes](../errorcode-universal.md).

| ID| Error Message|
| -------- | -------- |
| 401 | parameter error. Possible causes: 1. Missing mandatory parameters 2. Incorrect parameter type |
| 13400003 | task service ability error. |
| 21900006 | task not found. |

**Example**

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

  request.agent.show("123456", (err: BusinessError, taskInfo: request.agent.TaskInfo) => {
    if (err) {
      console.error(`Failed to show a upload task, Code: ${err.code}, message: ${err.message}`);
      return;
    }
    console.info(`Succeeded in showing a upload task.`);
  });
  ```


## request.agent.show<sup>10+</sup>

show(id: string): Promise&lt;TaskInfo&gt;

Queries a task details based on the task ID. This API uses a promise to return the result.

**System capability**: SystemCapability.Request.FileTransferAgent

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| id | string | Yes| Task ID.|

**Return value**

| Type               | Description                     |
| ------------------- | ------------------------- |
| Promise&lt;[TaskInfo](#taskinfo10)&gt; | Promise used to return the **TaskInfo** object.|

**Error codes**
For details about the error codes, see [Upload and Download Error Codes](errorcode-request.md) and [Universal Error Codes](../errorcode-universal.md).

| ID| Error Message|
| -------- | -------- |
| 401 | parameter error. Possible causes: 1. Missing mandatory parameters 2. Incorrect parameter type |
| 13400003 | task service ability error. |
| 21900006 | task not found. |

**Example**

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

  request.agent.show("123456").then((taskInfo: request.agent.TaskInfo) => {
    console.info(`Succeeded in showing a upload task.`);
  }).catch((err: BusinessError) => {
    console.error(`Failed to show a upload task, Code: ${err.code}, message: ${err.message}`);
  });
  ```


## request.agent.touch<sup>10+</sup>

touch(id: string, token: string, callback: AsyncCallback&lt;TaskInfo&gt;): void

Queries the task details based on the task ID and token. This API uses an asynchronous callback to return the result.

**System capability**: SystemCapability.Request.FileTransferAgent

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| id | string | Yes| Task ID.|
| token | string | Yes| Token for task query.|
| callback | AsyncCallback&lt;[TaskInfo](#taskinfo10)&gt; | Yes| Callback used to return the result. If the operation is successful, **err** is **undefined** and **data** is the **TaskInfo** object obtained. Otherwise, **err** is an error object.|

**Error codes**
For details about the error codes, see [Upload and Download Error Codes](errorcode-request.md) and [Universal Error Codes](../errorcode-universal.md).

| ID| Error Message|
| -------- | -------- |
| 401 | parameter error. Possible causes: 1. Missing mandatory parameters 2. Incorrect parameter type 3. Parameter verification failed |
| 13400003 | task service ability error. |
| 21900006 | task not found. |

**Example**

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

  request.agent.touch("123456", "token", (err: BusinessError, taskInfo: request.agent.TaskInfo) => {
    if (err) {
      console.error(`Failed to touch a upload task, Code: ${err.code}, message: ${err.message}`);
      return;
    }
    console.info(`Succeeded in touching a upload task.`);
  });
  ```


## request.agent.touch<sup>10+</sup>

touch(id: string, token: string): Promise&lt;TaskInfo&gt;

Queries the task details based on the task ID and token. This API uses a promise to return the result.

**System capability**: SystemCapability.Request.FileTransferAgent

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| id | string | Yes| Task ID.|
| token | string | Yes| Token for task query.|

**Return value**

| Type               | Description                     |
| ------------------- | ------------------------- |
| Promise&lt;[TaskInfo](#taskinfo10)&gt; | Promise used to return the **TaskInfo** object.|

**Error codes**
For details about the error codes, see [Upload and Download Error Codes](errorcode-request.md) and [Universal Error Codes](../errorcode-universal.md).

| ID| Error Message|
| -------- | -------- |
| 401 | parameter error. Possible causes: 1. Missing mandatory parameters 2. Incorrect parameter type 3. Parameter verification failed |
| 13400003 | task service ability error. |
| 21900006 | task not found. |

**Example**

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

  request.agent.touch("123456", "token").then((taskInfo: request.agent.TaskInfo) => {
    console.info(`Succeeded in touching a upload task. `);
  }).catch((err: BusinessError) => {
    console.error(`Failed to touch a upload task, Code: ${err.code}, message: ${err.message}`);
  });
  ```

## request.agent.search<sup>10+</sup>

search(callback: AsyncCallback&lt;Array&lt;string&gt;&gt;): void

Searches for task IDs based on [Filter](#filter10). This API uses an asynchronous callback to return the result.

**System capability**: SystemCapability.Request.FileTransferAgent

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| callback | AsyncCallback&lt;Array&lt;string&gt;&gt; | Yes| Callback used to return the result. If the operation is successful, **err** is **undefined** and **data** is the task ID. Otherwise, **err** is an error object.|

**Error codes**
For details about the error codes, see [Upload and Download Error Codes](errorcode-request.md) and [Universal Error Codes](../errorcode-universal.md).

| ID| Error Message|
| -------- | -------- |
| 401 | parameter error. Possible causes: 1. Incorrect parameter type 2. Parameter verification failed |
| 13400003 | task service ability error. |

**Example**

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

  request.agent.search((err: BusinessError, data: Array<string>) => {
    if (err) {
      console.error(`Failed to search a upload task, Code: ${err.code}, message: ${err.message}`);
      return;
    }
    console.info(`Succeeded in searching a upload task. `);
  });
  ```

## request.agent.search<sup>10+</sup>

search(filter: Filter, callback: AsyncCallback&lt;Array&lt;string&gt;&gt;): void

Searches for task IDs based on [Filter](#filter10). This API uses an asynchronous callback to return the result.

**System capability**: SystemCapability.Request.FileTransferAgent

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| filter | [Filter](#filter10) | Yes| Filter criteria.|
| callback | AsyncCallback&lt;Array&lt;string&gt;&gt; | Yes| Callback used to return the result. If the operation is successful, **err** is **undefined** and **data** is the task ID. Otherwise, **err** is an error object.|

**Error codes**
For details about the error codes, see [Upload and Download Error Codes](errorcode-request.md) and [Universal Error Codes](../errorcode-universal.md).

| ID| Error Message|
| -------- | -------- |
| 401 | parameter error. Possible causes: 1. Incorrect parameter type 2. Parameter verification failed |
| 13400003 | task service ability error. |

**Example**

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

  let filter: request.agent.Filter = {
    action: request.agent.Action.UPLOAD,
    mode: request.agent.Mode.BACKGROUND
  }
  request.agent.search(filter, (err: BusinessError, data: Array<string>) => {
    if (err) {
      console.error(`Failed to search a upload task, Code: ${err.code}, message: ${err.message}`);
      return;
    }
    console.info(`Succeeded in searching a upload task. `);
  });
  ```


## request.agent.search<sup>10+</sup>

search(filter?: Filter): Promise&lt;Array&lt;string&gt;&gt;

Searches for task IDs based on [Filter](#filter10). This API uses a promise to return the result.

**System capability**: SystemCapability.Request.FileTransferAgent

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| filter | [Filter](#filter10) | No| Filter criteria.|

**Return value**

| Type               | Description                     |
| ------------------- | ------------------------- |
| Promise&lt;Array&lt;string&gt;&gt; | Promise Promise used to return task ID matches.|

**Error codes**
For details about the error codes, see [Upload and Download Error Codes](errorcode-request.md) and [Universal Error Codes](../errorcode-universal.md).

| ID| Error Message|
| -------- | -------- |
| 401 | parameter error. Possible causes: 1. Incorrect parameter type 2. Parameter verification failed |
| 13400003 | task service ability error. |

**Example**

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

  let filter: request.agent.Filter = {
    action: request.agent.Action.UPLOAD,
    mode: request.agent.Mode.BACKGROUND
  }
  request.agent.search(filter).then((data: Array<string>) => {
    console.info(`Succeeded in searching a upload task. `);
  }).catch((err: BusinessError) => {
    console.error(`Failed to search a upload task, Code: ${err.code}, message: ${err.message}`);
  });
  ```