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en/application-dev/database/database-distributedobject-guidelines.md
浏览文件 @ a5bd2664
......@@ -13,62 +13,107 @@ Call **createDistributedObject()** to create a distributed data object instance.
**Table 1** API for creating a distributed data object instance
| Package | API | Description |
| -------- | -------- | -------- |
| ohos.data.distributedDataObject | createDistributedObject(source: object): DistributedObject | Creates a distributed data object instance for data operations.<br>-&nbsp;**source**: attributes of the **distributedObject** set.<br>-&nbsp;**DistributedObject**: returns the distributed object created. |
| Package| API| Description|
| -------- | -------- | -------- |
| ohos.data.distributedDataObject| createDistributedObject(source: object): DistributedObject | Creates a distributed data object instance for data operations.<br>-&nbsp;**source**: attributes of the **distributedObject** set.<br>-&nbsp;**DistributedObject**: returns the distributed object created.|
### Generating a Session ID
Call **genSessionId()** to generate a session ID randomly. The generated session ID can be used to set the session ID of a distributed data object.
**Table 2** API for generating a session ID randomly
| Package | API | Description |
| -------- | -------- | -------- |
| ohos.data.distributedDataObject | genSessionId(): string | Generates a session ID, which can be used as the session ID of a distributed data object. |
| Package| API| Description|
| -------- | -------- | -------- |
| ohos.data.distributedDataObject| genSessionId(): string | Generates a session ID, which can be used as the session ID of a distributed data object.|
### Setting a SessionID for Distributed Data Objects
Call **setSessionId()** to set a session ID for a distributed data object. The session ID is a unique identifier for one collaboration across devices. The distributed data objects to be synchronized must be associated with the same session ID.
**Table 3** API for setting a session ID
| Class | API | Description |
| -------- | -------- | -------- |
| DistributedDataObject | setSessionId(sessionId?: string): boolean | Sets a session ID for distributed data objects.<br>**sessionId**: session ID of a distributed object in a trusted network. To remove a distributed data object from the network, set this parameter to "" or leave it empty. |
| Class| API| Description|
| -------- | -------- | -------- |
| DistributedDataObject | setSessionId(sessionId?: string): boolean | Sets a session ID for distributed data objects.<br>&nbsp;**sessionId**: session ID of a distributed object in a trusted network. To remove a distributed data object from the network, set this parameter to "" or leave it empty.|
### Observing Data Changes
Call **on()** to subscribe to data changes of a distributed data object. When the data changes, a callback will be invoked to return the data changes. You can use **off()** to unsubscribe from the data changes.
**Table 4** APIs for observing data changes of a distributed data object
| Class | API | Description |
| -------- | -------- | -------- |
| DistributedDataObject | on(type: 'change', callback: Callback<{ sessionId: string, fields: Array&lt;string&gt; }>): void | Subscribes to data changes. |
| DistributedDataObject | off(type: 'change', callback?: Callback<{ sessionId: string, fields: Array&lt;string&gt; }>): void | Unsubscribes from data changes. <br>**Callback**: specifies callback used to return changes of the distributed data object. If this parameter is not specified, all callbacks related to data changes will be unregistered. |
| Class| API| Description|
| -------- | -------- | -------- |
| DistributedDataObject| on(type: 'change', callback: Callback<{ sessionId: string, fields: Array&lt;string&gt; }>): void | Subscribes to data changes.|
| DistributedDataObject| off(type: 'change', callback?: Callback<{ sessionId: string, fields: Array&lt;string&gt; }>): void | Unsubscribes from data changes. **Callback**: specifies callback used to return changes of the distributed data object. If this parameter is not specified, all callbacks related to data changes will be unregistered.|
### Observing Online or Offline Status
Call **on()** to subscribe to status changes of a distributed data object. The status can be online or offline. When the status changes, a callback will be invoked to return the status. You can use **off()** to unsubscribe from the status changes.
**Table 5** APIs for observing status changes of a distributed data object
| Class | API | Description |
| -------- | -------- | -------- |
| DistributedDataObject | on(type: 'status', callback: Callback<{ sessionId: string, networkId: string, status: 'online' \ | 'offline' }>): void | Subscribes to the status changes of a distributed data object. |
| DistributedDataObject | off(type: 'status', callback?: Callback<{ sessionId: string, deviceId: string, status: 'online' \ | 'offline' }>): void | Unsubscribes from status changes of a distributed data object. |
| Class| API| Description|
| -------- | -------- | -------- |
| DistributedDataObject| on(type: 'status', callback: Callback<{ sessionId: string, networkId: string, status: 'online' \| 'offline' }>): void | Subscribes to the status changes of a distributed data object.|
| DistributedDataObject| off(type: 'status', callback?: Callback<{ sessionId: string, deviceId: string, status: 'online' \| 'offline' }>): void | Unsubscribes from status changes of a distributed data object.|
### Saving a Distributed Data Object and Revoking the Data Saving Operation
Call **save()** to save a distributed data object. When the application is active, the saved data will not be released. When the application exits and restarts, the data saved on the device will be restored.
Call **revokeSave()** to revoke a distributed data object that is no longer required. If the distributed data object is saved on the local device, **revokeSave()** will delete the data from all trusted devices. If the distributed data object is not saved on the local device, **revokeSave()** will delete the data from the local device.
The saved data will be released in the following cases:
- The data is stored for more than 24 hours.
- The application has been uninstalled.
- Data is successfully restored.
**Table 6** APIs for saving a distributed data object and revoking the saving
| Class| API| Description|
| -------- | -------- | -------- |
| DistributedDataObject | save(deviceId: string): Promise&lt;SaveSuccessResponse&gt; | Saves a distributed data object. This API uses a promise to return the result.|
| DistributedDataObject| save(deviceId: string, callback: AsyncCallback&lt;SaveSuccessResponse&gt;): void | Saves a distributed data object. This API uses an asynchronous callback to return the result.|
| DistributedDataObject | revokeSave(callback: AsyncCallback&lt;RevokeSaveSuccessResponse&gt;): void | Revokes the data saving operation. This API uses an asynchronous callback to return the result. |
| DistributedDataObject| revokeSave(): Promise&lt;RevokeSaveSuccessResponse&gt; | Revokes the data saving operation. This API uses a promise to return the result. |
## How to Develop
The following example shows how to implement a distributed data object synchronization.
1. Import the @ohos.data.distributedDataObject module to the development environment.
```js
import distributedObject from '@ohos.data.distributedDataObject'
```js
import distributedObject from '@ohos.data.distributedDataObject';
```
2. Request the permission. <br>Add the required permission in the **config.json** file. The sample code is as follows:
```
{
"module": {
"reqPermissions": [
{
"name": "ohos.permission.DISTRIBUTED_DATASYNC"
}
]
}
}
```
This permission must also be authorized by the user through a dialog box when the application is started for the first time. The sample code is as follows:
```js
import featureAbility from '@ohos.ability.featureAbility';
function grantPermission() {
console.info('grantPermission');
let context = featureAbility.getContext();
context.requestPermissionsFromUser(['ohos.permission.DISTRIBUTED_DATASYNC'], 666, function (result) {
console.info(`result.requestCode=${result.requestCode}`)
})
console.info('end grantPermission');
}
grantPermission();
```
2. Obtain a distributed data object instance.
3. Obtain a distributed data object instance.
The sample code is as follows:
```js
var local_object = distributedObject.createDistributedObject({name:undefined, age:undefined, isVis:true,
parent:undefined, list:undefined});
......@@ -76,7 +121,9 @@ The following example shows how to implement a distributed data object synchroni
```
3. Add the synchronization network. The data objects in the synchronization network include the local and remote objects.
4. Add the synchronization network. The data objects in the synchronization network include the local and remote objects.
The sample code is as follows:
```js
// Local object
......@@ -91,8 +138,10 @@ The following example shows how to implement a distributed data object synchroni
// After learning that the device goes online, the remote object synchronizes data. That is, name changes to jack and age to 18.
```
4. Observe the data changes of the distributed data object. You can subscribe to data changes of the remote object. When the data in the remote object changes, a callback will be called to return the data changes.
5. Observe the data changes of the distributed data object. <br>You can subscribe to data changes of the peer object. When the data in the peer object changes, a callback will be called to return the data changes.
The sample code is as follows:
```js
function changeCallback(sessionId, changeData) {
console.info("change" + sessionId);
......@@ -103,13 +152,14 @@ The following example shows how to implement a distributed data object synchroni
});
}
}
// To refresh the page in changeCallback, correctly bind (this) to the changeCallback.
local_object.on("change", this.changeCallback.bind(this));
```
5. Modify object attributes. The object attributes support basic data types (such as number, Boolean, and string) and complex data types (array and nested basic types).
6. Modify object attributes. <br>The object attributes support basic data types (such as number, Boolean, and string) and complex data types (array and nested basic types).
The sample code is as follows:
```js
local_object.name = "jack";
local_object.age = 19;
......@@ -127,23 +177,23 @@ The following example shows how to implement a distributed data object synchroni
local_object.parent.mother = "mom";
```
6. Access the distributed data object. Obtain the distributed data object attribute, which is the latest data on the network.
7. Access the distributed data object. <br>Obtain the distributed data object attribute, which is the latest data on the network.
The sample code is as follows:
```js
console.info("name " + local_object["name"]);
```
8. Unsubscribe from data changes. <br>You can specify the callback to unregister. If you do not specify the callback, all data change callbacks of the distributed data object will be unregistered.
7. Unsubscribe from data changes. You can specify the callback to unsubscribe from. If you do not specify the callback, all data change callbacks of the distributed data object will be unsubscribed from.
The sample code is as follows:
```js
// Unsubscribe from the specified data change callback.
// Unregister the specified data change callback.
local_object.off("change", changeCallback);
// Unsubscribe from all data change callbacks.
// Unregister all data change callbacks.
local_object.off("change");
```
8. Subscribe to the status (online/offline) changes of the distributed data object. A callback will be invoked to report the status change when the target distributed data object goes online or offline.
9. Subscribe to the status (online/offline) changes of the distributed data object. A callback will be invoked to report the status change when the target distributed data object goes online or offline.
The sample code is as follows:
```js
function statusCallback(sessionId, networkId, status) {
this.response += "status changed " + sessionId + " " + status + " " + networkId;
......@@ -152,17 +202,63 @@ The following example shows how to implement a distributed data object synchroni
local_object.on("status", this.statusCallback);
```
9. Unsubscribe from the status changes of the distributed data object. You can specify the callback to unsubscribe from. If you do not specify the callback, this API unsubscribes from all callbacks of this distributed data object.
10. Save a distributed data object and revoke the data saving operation.
- Callback
```js
// Unsubscribe from the specified status change callback.
local_object.off("status", statusCallback);
// Unsubscribe from all status change callbacks.
local_object.off("status");
```
10. Remove a distributed data object from the synchronization network. Data changes on the local object will not be synchronized to the removed distributed data object.
```js
// Save a distributed data object.
local_object.save("local", (result, data)=>{
console.log("save callback");
console.info("save sessionId " + data.sessionId);
console.info("save version " + data.version);
console.info("save deviceId " + data.deviceId);
});
// Revoke the data saving operation.
local_object.revokeSave((result, data) =>{
console.log("revokeSave callback");
console.info("revokeSave sessionId " + data.sessionId);
});
```
- Promise
```js
local_object.setSessionId("");
```
\ No newline at end of file
// Save a distributed data object.
g_object.save("local").then((result)=>{
console.info("save sessionId " + result.sessionId);
console.info("save version " + result.version);
console.info("save deviceId " + result.deviceId);
}, (result)=>{
console.info("save local failed.");
});
// Revoke the data saving operation.
g_object.revokeSave().then((result)=>{
console.info("revokeSave success.");
}, (result)=>{
console.info("revokeSave failed.");
});
```
11. Unsubscribe from the status changes of the distributed data object. <br>You can specify the callback to unregister. If you do not specify the callback, this API unregister all callbacks of this distributed data object.
The sample code is as follows:
```js
// Unregister the specified status change callback.
local_object.off("status", this.statusCallback);
// Unregister all status change callbacks.
local_object.off("status");
```
12. Remove a distributed data object from the synchronization network. Data changes on the local object will not be synchronized to the removed distributed data object.
The sample code is as follows:
```js
local_object.setSessionId("");
```
## Development Example
The following example is provided for you to better understand the development of distributed data objects:
- [Distributed Notepad](https://gitee.com/openharmony/distributeddatamgr_objectstore/tree/master/samples/distributedNotepad)
When an event of the Notepad app occurs on a device, such as a note is added, the tile or content of a note is changed, or the event list is cleared, the change will be synchronized to other devices in the trusted network.
en/application-dev/reference/apis/js-apis-data-distributedobject.md
浏览文件 @ a5bd2664
# Distributed Data Object
Provides basic data object management, including creating, querying, deleting, modifying, and subscribing to data objects, and distributed data object collaboration for the same application among multiple devices.
> **NOTE**<br/>
>
> The initial APIs of this module are supported since API version 8. Newly added APIs will be marked with a superscript to indicate their earliest API version.
......@@ -20,9 +23,9 @@ Creates a distributed data object.
**System capability**: SystemCapability.DistributedDataManager.DataObject.DistributedObject
**Parameters**
| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| source | object | Yes| Attribute of the distributed data object to create.|
| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| source | object | Yes| Attribute of the distributed data object to create.|
**Return value**
| Type| Description|
......@@ -31,14 +34,14 @@ Creates a distributed data object.
**Example**
```js
import distributedObject from '@ohos.data.distributedDataObject'
import distributedObject from '@ohos.data.distributedDataObject';
// Create a distributed data object, which contains attributes of four types, namely, string, number, boolean, and object.
var g_object = distributedObject.createDistributedObject({name:"Amy", age:18, isVis:false,
parent:{mother:"jack mom",father:"jack Dad"}});
```
## distributedObject.genSessionId()
## distributedObject.genSessionId
genSessionId(): string
......@@ -47,16 +50,37 @@ Creates a random session ID.
**System capability**: SystemCapability.DistributedDataManager.DataObject.DistributedObject
**Return value**
| Type| Description|
| -------- | -------- |
| string | Session ID created.|
| Type| Description|
| -------- | -------- |
| string | Session ID created.|
**Example**
```js
import distributedObject from '@ohos.data.distributedDataObject'
import distributedObject from '@ohos.data.distributedDataObject';
var sessionId = distributedObject.genSessionId();
```
## SaveSuccessResponse<sup>9+</sup>
Called when the **Save()** API is successfully called.
**System capability**: SystemCapability.DistributedDataManager.DataObject.DistributedObject
| Name| Type| Description|
| -------- | -------- | -------- |
| sessionId | string | Unique ID for multi-device collaboration.|
| version | number |Version of the distributed data object saved.|
| deviceId | string | ID of the device where the distributed data object is stored. The default value is **local**, which identifies a local device. You can set it as required.|
## RevokeSaveSuccessResponse<sup>9+</sup>
Called when the **revokeSave()** API is successfully called.
**System capability**: SystemCapability.DistributedDataManager.DataObject.DistributedObject
| Name| Type| Description|
| -------- | -------- | -------- |
| sessionId | string | Unique ID for multi-device collaboration.|
## DistributedObject
......@@ -68,24 +92,26 @@ setSessionId(sessionId?: string): boolean
Sets a session ID for synchronization. Automatic synchronization is performed for multiple devices with the same session ID on a trusted network.
**Required permissions**: ohos.permission.DISTRIBUTED_DATASYNC
**System capability**: SystemCapability.DistributedDataManager.DataObject.DistributedObject
**Parameters**
| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| sessionId | string | No| ID of a distributed data object on a trusted network. To remove a distributed data object from the network, set this parameter to "" or leave it empty.|
| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| sessionId | string | No| ID of a distributed data object on a trusted network. To remove a distributed data object from the network, set this parameter to "" or leave it empty.|
**Return value**
| Type| Description|
| -------- | -------- |
| boolean | Returns **true** if the session ID is set successfully;<br>returns **false** otherwise. |
| Type| Description|
| -------- | -------- |
| boolean | Returns **true** if the session ID is set successfully;<br>returns **false** otherwise. |
**Example**
```js
import distributedObject from '@ohos.data.distributedDataObject'
import distributedObject from '@ohos.data.distributedDataObject';
var g_object = distributedObject.createDistributedObject({name:"Amy", age:18, isVis:false,
parent:{mother:"jack mom",father:"jack Dad"}});
// Add g_object to the distributed network.
......@@ -104,25 +130,25 @@ Subscribes to the changes of this distributed data object.
**System capability**: SystemCapability.DistributedDataManager.DataObject.DistributedObject
**Parameters**
| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| type | string | Yes| Event type to subscribe to. The value is **change**, which indicates data changes.|
| callback | Callback<{ sessionId: string, fields: Array&lt;string&gt; }> | Yes| Callback used to return the changes of the distributed data object.<br>**sessionId** indicates the session ID of the distributed data object.<br>**fields** indicates the changed attributes of the distributed data object.|
| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| type | string | Yes| Event type to subscribe to. The value is **change**, which indicates data changes.|
| callback | Callback<{ sessionId: string, fields: Array&lt;string&gt; }> | Yes| Callback used to return the changes of the distributed data object.<br>**sessionId** indicates the session ID of the distributed data object.<br>**fields** indicates the changed attributes of the distributed data object.|
**Example**
```js
import distributedObject from '@ohos.data.distributedDataObject'
var g_object = distributedObject.createDistributedObject({name:"Amy", age:18, isVis:false,
parent:{mother:"jack mom",father:"jack Dad"}});
g_object.on("change", function (sessionId, changeData) {
console.info("change" + sessionId);
if (changeData != null && changeData != undefined) {
changeData.forEach(element => {
console.info("changed !" + element + " " + g_object[element]);
});
}
});
```
```js
import distributedObject from '@ohos.data.distributedDataObject';
var g_object = distributedObject.createDistributedObject({name:"Amy", age:18, isVis:false,parent:{mother:"jack mom",father:"jack Dad"}});
globalThis.changeCallback = (sessionId, changeData) => {
console.info("change" + sessionId);
if (changeData != null && changeData != undefined) {
changeData.forEach(element => {
console.info("changed !" + element + " " + g_object[element]);
});
}
}
g_object.on("change", globalThis.changeCallback);
```
### off('change')
......@@ -133,27 +159,21 @@ Unsubscribes from the changes of this distributed data object.
**System capability**: SystemCapability.DistributedDataManager.DataObject.DistributedObject
**Parameters**
| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| type | string | Yes| Event type to unsubscribe from. The value is **change**, which indicates data changes.|
| callback | Callback<{ sessionId: string, fields: Array&lt;string&gt; }> | No| Callback used to return the changes of the distributed data object. If this parameter is not specified, this API unsubscribes from all callbacks for data changes of this distributed data object.<br>**sessionId** indicates the session ID of the distributed data object.<br>**fields** indicates the changed attributes of the distributed data object.|
| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| type | string | Yes| Event type to unsubscribe from. The value is **change**, which indicates data changes.|
| callback | Callback<{ sessionId: string, fields: Array&lt;string&gt; }> | No| Callback to be unregistered. If this parameter is not set, all data change callbacks of the object will be unregistered.<br>**sessionId** indicates the session ID of the distributed data object.<br>**fields** indicates the changed attributes of the distributed data object.|
**Example**
```js
import distributedObject from '@ohos.data.distributedDataObject'
var g_object = distributedObject.createDistributedObject({name:"Amy", age:18, isVis:false,
parent:{mother:"jack mom",father:"jack Dad"}});
g_object.on("change", function (sessionId, changeData) {
console.info("change" + sessionId);
});
// Unsubscribe from the specified data change callback for the distributed data object.
g_object.off("change", function (sessionId, changeData) {
console.info("change" + sessionId);
});
// Unsubscribe from all data change callbacks for the distributed data object.
g_object.off("change");
```
```js
import distributedObject from '@ohos.data.distributedDataObject';
var g_object = distributedObject.createDistributedObject({name:"Amy", age:18, isVis:false,parent:{mother:"jack mom",father:"jack Dad"}});
// Unregister the specified data change callback.
g_object.off("change", globalThis.changeCallback);
// Unregister all data change callbacks.
g_object.off("change");
```
### on('status')
......@@ -164,20 +184,20 @@ Subscribes to the status change (online or offline) of this distributed data obj
**System capability**: SystemCapability.DistributedDataManager.DataObject.DistributedObject
**Parameters**
| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| type | string | Yes| Event type to subscribe to. The value is **status**, which indicates the change in the status (online or offline) of the distributed data object.|
| callback | Callback<{ sessionId: string, networkId: string, status: 'online' \| 'offline' }> | Yes| Callback used to return the status change.<br>**sessionId** indicates the session ID of the distributed data object.<br>**networkId** indicates the network ID of the device.<br>**status** indicates the status, which can be online or offline.|
| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| type | string | Yes| Event type to subscribe to. The value is **status**, which indicates the status change (online or offline) of the distributed data object.|
| callback | Callback<{ sessionId: string, networkId: string, status: 'online' \| 'offline' }> | Yes| Callback used to return the status change.<br>**sessionId**: session ID of the distributed data object.<br>**networkId**: object device ID, that is, **deviceId**.<br>**status** indicates the object status, which can be online or offline. |
**Example**
```js
import distributedObject from '@ohos.data.distributedDataObject'
var g_object = distributedObject.createDistributedObject({name:"Amy", age:18, isVis:false,
parent:{mother:"jack mom",father:"jack Dad"}});
g_object.on("status", function (sessionId, networkid, status) {
this.response += "status changed " + sessionId + " " + status + " " + networkId;
});
```
```js
import distributedObject from '@ohos.data.distributedDataObject';
globalThis.statusCallback = (sessionId, networkId, status) => {
globalThis.response += "status changed " + sessionId + " " + status + " " + networkId;
}
var g_object = distributedObject.createDistributedObject({name:"Amy", age:18, isVis:false,parent:{mother:"jack mom",father:"jack Dad"}});
g_object.on("status", globalThis.statusCallback);
```
### off('status')
......@@ -189,22 +209,158 @@ Unsubscribes from the status change (online or offline) of this distributed data
**System capability**: SystemCapability.DistributedDataManager.DataObject.DistributedObject
**Parameters**
| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| type | string | Yes| Event type to unsubscribe from. The value is **status**, which indicates the change in the status (online or offline) of the distributed data object.|
| callback | Callback<{ sessionId: string, deviceId: string, status: 'online' \| 'offline' }> | No| Callback used to return the status change. If this parameter is not specified, this API unsubscribes from all callbacks of this distributed data object.<br>**sessionId** indicates the session ID of the distributed data object.<br>**deviceId** indicates the device ID of the distributed data object.<br>**status** indicates the status, which can be online or offline.|
| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| type | string | Yes| Event type to unsubscribe from. The value is **status**, which indicates the status change (online or offline) of the distributed data object.|
| callback | Callback<{ sessionId: string, deviceId: string, status: 'online' \| 'offline' }> | No| Callback used to return the status change. If this parameter is not specified, this API unsubscribes from all callbacks of this distributed data object.<br>**sessionId**: session ID of the distributed data object.<br>**deviceId** indicates the device ID of the distributed data object.<br>**status** indicates the status, which can be online or offline.|
**Example**
```js
import distributedObject from '@ohos.data.distributedDataObject'
g_object.on("status", function (sessionId, networkId, status) {
this.response += "status changed " + sessionId + " " + status + " " + networkId;
```js
import distributedObject from '@ohos.data.distributedDataObject';
var g_object = distributedObject.createDistributedObject({name:"Amy", age:18, isVis:false,parent:{mother:"jack mom",father:"jack Dad"}});
globalThis.statusCallback = (sessionId, networkId, status) => {
globalThis.response += "status changed " + sessionId + " " + status + " " + networkId;
}
// Unsubscribe from the specified status change callback for the distributed data object.
g_object.off("status",globalThis.statusCallback);
// Unsubscribe from all status change callbacks for the distributed data object.
g_object.off("status");
```
### save<sup>9+</sup>
save(deviceId: string, callback: AsyncCallback&lt;SaveSuccessResponse&gt;): void
Saves a distributed data object. This API uses an asynchronous callback to return the result.
If the application is active, the saved data will not be released. When the application exits and restarts, the data saved on the device will be restored.
The saved data will be released in the following cases:
- The data is stored for more than 24 hours.
- The application has been uninstalled.
- Data is successfully restored.
**System capability**: SystemCapability.DistributedDataManager.DataObject.DistributedObject
**Parameters**
| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| deviceId | string | Yes| ID of the device where data is stored. The value **local** indicates the local device.|
| callback | AsyncCallback&lt;[SaveSuccessResponse](#savesuccessresponse)&gt; | Yes| Callback used to return **SaveSuccessResponse**, which contains information such as session ID, version, and device ID.|
**Example**
```ts
import distributedObject from '@ohos.data.distributedDataObject';
var g_object = distributedObject.createDistributedObject({name:"Amy", age:18, isVis:false});
g_object.setSessionId("123456");
g_object.save("local", (result)=>{
console.log("save callback");
console.info("save sessionId " + result.sessionId);
console.info("save version " + result.version);
console.info("save deviceId " + result.deviceId);
});
```
### save<sup>9+</sup>
save(deviceId: string): Promise&lt;SaveSuccessResponse&gt;
Saves a distributed data object. This API uses a promise to return the result.
If the application is active, the saved data will not be released. When the application exits and restarts, the data saved on the device will be restored.
The saved data will be released in the following cases:
- The data is stored for more than 24 hours.
- The application has been uninstalled.
- Data is successfully restored.
**System capability**: SystemCapability.DistributedDataManager.DataObject.DistributedObject
**Parameters**
| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| deviceId | string | Yes| ID of the device where the data is saved. The default value is **local**, which indicates the local device. |
**Return value**
| Type| Description|
| -------- | -------- |
| Promise&lt;[SaveSuccessResponse](#savesuccessresponse)&gt; | Promise used to return **SaveSuccessResponse**, which contains information such as session ID, version, and device ID.|
**Example**
```ts
import distributedObject from '@ohos.data.distributedDataObject';
var g_object = distributedObject.createDistributedObject({name:"Amy", age:18, isVis:false});
g_object.setSessionId("123456");
g_object.save("local").then((result)=>{
console.log("save callback");
console.info("save sessionId " + result.sessionId);
console.info("save version " + result.version);
console.info("save deviceId " + result.deviceId);
}, ()=>{
console.error("save failed");
});
```
### revokeSave<sup>9+</sup>
revokeSave(callback: AsyncCallback&lt;SaveSuccessResponse&gt;): void
Revokes the saving operation of a distributed data object. This API uses an asynchronous callback to return the result.
If the object is saved on the local device, the data saved on all trusted devices will be deleted.
If the object is stored on another device, the data on the local device will be deleted.
**System capability**: SystemCapability.DistributedDataManager.DataObject.DistributedObject
**Parameters**
| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| callback | AsyncCallback&lt;[RevokeSaveSuccessResponse](#revokesavesuccessresponse)&gt; | No| Callback used to return **RevokeSaveSuccessResponse**, which contains the session ID.|
**Example**
```ts
import distributedObject from '@ohos.data.distributedDataObject';
var g_object = distributedObject.createDistributedObject({name:"Amy", age:18, isVis:false});
g_object.setSessionId("123456");
g_object.revokeSave((result, data) =>{
console.log("revokeSave callback");
});
// Unsubscribe from the specified status change callback for the distributed data object.
g_object.off("status", function (sessionId, networkId, status) {
this.response += "status changed " + sessionId + " " + status + " " + networkId;
```
### revokeSave<sup>9+</sup>
revokeSave(): Promise&lt;SaveSuccessResponse&gt;
Revokes the saving operation of a distributed data object. This API uses a promise to return the result.
If the object is saved on the local device, the data saved on all trusted devices will be deleted.
If the object is stored on another device, the data on the local device will be deleted.
**System capability**: SystemCapability.DistributedDataManager.DataObject.DistributedObject
**Return value**
| Type| Description|
| -------- | -------- |
| Promise&lt;[RevokeSaveSuccessResponse](#revokesavesuccessresponse)&gt; | Promise used to return **RevokeSaveSuccessResponse**, which contains the session ID.|
**Example**
```ts
import distributedObject from '@ohos.data.distributedDataObject';
var g_object = distributedObject.createDistributedObject({name:"Amy", age:18, isVis:false});
g_object.setSessionId("123456");
g_object.revokeSave("local").then((result)=>{
console.log("revokeSave callback");
console.log("sessionId" + result.sessionId);
}, ()=>{
console.error("revokeSave failed");
});
// Unsubscribe from all status change callbacks for the distributed data object.
g_object.off("status");
```
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