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en/application-dev/database/database-distributedobject-guidelines.md
浏览文件 @ 028c171b
......@@ -6,6 +6,7 @@ The distributed data objects allow data across devices to be processed like loca
## Available APIs
For details about the APIs related to the distributed data object, see [Distributed Data Object](../reference/apis/js-apis-data-distributedobject.md).
### Creating a Distributed Data Object Instance
......@@ -93,7 +94,7 @@ 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.
4. Observe the data changes of the distributed data object. 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:
......@@ -107,7 +108,7 @@ 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));
```
......@@ -138,13 +139,13 @@ The following example shows how to implement a distributed data object synchroni
```js
console.info("name " + local_object["name"]);
```
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.
7. Unsubscribe from data changes. 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.
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.
......@@ -156,13 +157,13 @@ 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.
9. Unsubscribe from the status changes of the distributed data object. You can specify the callback to unregister. If you do not specify the callback, this API unregisters all callbacks of this distributed data object.
The sample code is as follows:
```js
// Unsubscribe from the specified status change callback.
// Unregister the specified status change callback.
local_object.off("status", statusCallback);
// Unsubscribe from all status change callbacks.
// Unregister 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.
......@@ -171,4 +172,12 @@ The following example shows how to implement a distributed data object synchroni
```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/database/database-mdds-guidelines.md
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......@@ -7,6 +7,8 @@ The Distributed Data Service (DDS) implements synchronization of application dat
## Available APIs
For details about the APIs related to distributed data, see [Distributed Data Management](../reference/apis/js-apis-distributed-data.md).
The table below describes the APIs provided by the OpenHarmony DDS module.
**Table 1** APIs provided by the DDS
......@@ -90,10 +92,10 @@ The following uses a single KV store as an example to describe the development p
}
```
> ![icon-note.gif](../public_sys-resources/icon-note.gif) **NOTE**<br/>
> ![icon-note.gif](public_sys-resources/icon-note.gif) **NOTE**<br/>
> For data synchronization between networked devices, you are advised to open the distributed KV store during application startup to obtain the database handle. With this database handle (**kvStore** in this example), you can perform operations, such as inserting data into the KV store, without creating the KV store repeatedly during the lifecycle of the handle.
4. Subscribe to changes in the distributed data.<br/>
4. Subscribe to changes in the distributed data.<br/>
The following is the sample code for subscribing to the data changes of a single KV store:
```js
kvStore.on('dataChange', distributedData.SubscribeType.SUBSCRIBE_TYPE_ALL, function (data) {
......@@ -175,3 +177,7 @@ The following uses a single KV store as an example to describe the development p
}
});
```
## Samples
The following samples are provided to help you better understand the distributed data development:
- [`KvStore`: Distributed Database (eTS) (API8)](https://gitee.com/openharmony/app_samples/tree/master/data/Kvstore)
- [Distributed Database](https://gitee.com/openharmony/codelabs/tree/master/Data/JsDistributedData)
en/application-dev/database/database-relational-guidelines.md
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......@@ -2,7 +2,7 @@
## When to Use
On the basis of the SQLite database, the relational database (RDB) allows you to operate data with or without native SQL statements. In OpenHarmony, an RDB is also called RDB store.
A relational database (RDB) store allows you to operate data with or without native SQL statements based on the SQLite database.
## Available APIs
......@@ -16,10 +16,10 @@ The following table describes the APIs available for creating and deleting an RD
| API| Description|
| -------- | -------- |
|getRdbStore(config: StoreConfig, version: number, callback: AsyncCallback&lt;RdbStore&gt;): void | Obtains an RDB store. This method uses a callback to return the result. You can set parameters for the RDB store based on service requirements, and then call APIs to perform data operations.<br>- **config**: configuration of the RDB store.<br>- **version**: RDB version.<br>- **callback**: callback invoked to return the RDB store obtained.|
|getRdbStore(config: StoreConfig, version: number): Promise&lt;RdbStore&gt; | Obtains an RDB store. This method uses a promise to return the result. You can set parameters for the RDB store based on service requirements, and then call APIs to perform data operations.<br>- **config**: configuration of the RDB store.<br>- **version**: RDB version.|
|deleteRdbStore(name: string, callback: AsyncCallback&lt;void&gt;): void | Deletes an RDB store. This method uses a callback to return the result. <br>- **name**: RDB store to delete.<br>- **callback**: callback invoked to return the result.|
| deleteRdbStore(name: string): Promise&lt;void&gt; | Deletes an RDB store. This method uses a promise to return the result.<br>- **name**: RDB store to delete.|
|getRdbStore(config: StoreConfig, version: number, callback: AsyncCallback&lt;RdbStore&gt;): void | Obtains an RDB store. This API uses a callback to return the result. You can set parameters for the RDB store based on service requirements, and then call APIs to perform data operations.<br>- **config**: configuration of the RDB store.<br>- **version**: RDB version.<br>- **callback**: callback invoked to return the RDB store obtained.|
|getRdbStore(config: StoreConfig, version: number): Promise&lt;RdbStore&gt; | Obtains an RDB store. This API uses a promise to return the result. You can set parameters for the RDB store based on service requirements, and then call APIs to perform data operations.<br>- **config**: configuration of the RDB store.<br>- **version**: RDB version.|
|deleteRdbStore(name: string, callback: AsyncCallback&lt;void&gt;): void | Deletes an RDB store. This API uses a callback to return the result. <br>- **name**: RDB store to delete.<br>- **callback**: callback invoked to return the result.|
| deleteRdbStore(name: string): Promise&lt;void&gt; | Deletes an RDB store. This API uses a promise to return the result.<br>- **name**: RDB store to delete.|
### Managing Data in an RDB Store
......@@ -33,8 +33,8 @@ The RDB provides APIs for inserting, deleting, updating, and querying data in th
| Class| API| Description|
| -------- | -------- | -------- |
| RdbStore | insert(name: string, values: ValuesBucket, callback: AsyncCallback&lt;number&gt;):void | Inserts a row of data into a table. This method uses a callback to return the result.<br>- **name**: name of the target table.<br>- **values**: data to be inserted into the table.<br>- **callback**: callback invoked to return the result. If the operation is successful, the row ID will be returned. Otherwise, **-1** will be returned.|
| RdbStore | insert(name: string, values: ValuesBucket): Promise&lt;number&gt; | Inserts a row of data into a table. This method uses a promise to return the result.<br>- **name**: name of the target table.<br>- **values**: data to be inserted into the table.|
| RdbStore | insert(name: string, values: ValuesBucket, callback: AsyncCallback&lt;number&gt;):void | Inserts a row of data into a table. This API uses a callback to return the result.<br>- **name**: name of the target table.<br>- **values**: data to be inserted into the table.<br>- **callback**: callback invoked to return the result. If the operation is successful, the row ID will be returned; otherwise, **-1** will be returned.|
| RdbStore | insert(name: string, values: ValuesBucket): Promise&lt;number&gt; | Inserts a row of data into a table. This API uses a promise to return the result.<br>- **name**: name of the target table.<br>- **values**: data to be inserted into the table.|
- **Updating data**
......@@ -44,8 +44,8 @@ The RDB provides APIs for inserting, deleting, updating, and querying data in th
| Class| API| Description|
| -------- | -------- | -------- |
| RdbStore | update(values: ValuesBucket, rdbPredicates: RdbPredicates, callback: AsyncCallback&lt;number&gt;):void | Updates data in the RDB store based on the specified **RdbPredicates** object. This method uses a callback to return the result.<br>- **values**: data to update, which is stored in a **ValuesBucket**.<br>- **rdbPredicates**: conditions for updating data.<br>- **callback**: callback invoked to return the number of rows updated.|
| RdbStore | update(values: ValuesBucket, rdbPredicates: RdbPredicates): Promise\<number> | Updates data in the RDB store based on the specified **RdbPredicates** object. This method uses a promise to return the result.<br>- **values**: data to update, which is stored in a **ValuesBucket**.<br>- **rdbPredicates**: conditions for updating data.|
| RdbStore | update(values: ValuesBucket, rdbPredicates: RdbPredicates, callback: AsyncCallback&lt;number&gt;):void | Updates data in the RDB store based on the specified **RdbPredicates** object. This API uses a callback to return the result.<br>- **values**: data to update, which is stored in a **ValuesBucket**.<br>- **rdbPredicates**: conditions for updating data.<br>- **callback**: callback invoked to return the number of rows updated.|
| RdbStore | update(values: ValuesBucket, rdbPredicates: RdbPredicates): Promise\<number> | Updates data in the RDB store based on the specified **RdbPredicates** object. This API uses a promise to return the result.<br>- **values**: data to update, which is stored in a **ValuesBucket**.<br>- **rdbPredicates**: conditions for updating data.|
- **Deleting data**
......@@ -55,8 +55,8 @@ The RDB provides APIs for inserting, deleting, updating, and querying data in th
| Class| API| Description|
| -------- | -------- | -------- |
| RdbStore | delete(rdbPredicates: RdbPredicates, callback: AsyncCallback&lt;number&gt;):void | Deletes data from the RDB store based on the specified **RdbPredicates** object. This method uses a callback to return the result.<br>- **rdbPredicates**: conditions for deleting data.<br>- **callback**: callback invoked to return the number of rows updated.|
| RdbStore | delete(rdbPredicates: RdbPredicates): Promise\<number> | Deletes data from the RDB store based on the specified **RdbPredicates** object. This method uses a promise to return the result.<br>- **rdbPredicates**: conditions for deleting data.|
| RdbStore | delete(rdbPredicates: RdbPredicates, callback: AsyncCallback&lt;number&gt;):void | Deletes data from the database based on the specified **RdbPredicates** object. This API uses a callback to return the result.<br>- **rdbPredicates**: conditions for deleting data.<br>- **callback**: callback invoked to return the number of rows updated.|
| RdbStore | delete(rdbPredicates: RdbPredicates): Promise\<number> | Deletes data from the RDB store based on the specified **RdbPredicates** object. This API uses a promise to return the result.<br>- **rdbPredicates**: conditions for deleting data.|
- **Querying data**
......@@ -69,10 +69,10 @@ The RDB provides APIs for inserting, deleting, updating, and querying data in th
| Class| API| Description|
| -------- | -------- | -------- |
| RdbStore | query(rdbPredicates: RdbPredicates, columns: Array, callback: AsyncCallback&lt;ResultSet&gt;): void | Queries data in the RDB store based on the specified **RdbPredicates** object. This method uses a callback to return the result.<br>- **rdbPredicates**: conditions for querying data.<br>- **columns**: columns to query. If this parameter is not specified, the query applies to all columns.<br>- **callback**: callback invoked to return the result. If the operation is successful, a **ResultSet** object will be returned.|
| RdbStore | query(rdbPredicates: RdbPredicates, columns: Array): Promise&lt;ResultSet&gt; | Queries data in the RDB store based on the specified **RdbPredicates** object. This method uses a promise to return the result.<br>- **rdbPredicates**: conditions for querying data.<br>- **columns**: columns to query. If this parameter is not specified, the query applies to all columns.|
| RdbStore | querySql(sql: string, bindArgs: Array&lt;ValueType&gt;, callback: AsyncCallback&lt;ResultSet&gt;):void | Queries data in the RDB store using the specified SQL statement. This method uses a callback to return the result.<br>- **sql**: SQL statement.<br>- **bindArgs**: arguments in the SQL statement.<br>- **callback**: callback invoked to return the result. If the operation is successful, a **ResultSet** object will be returned.|
| RdbStore | querySql(sql: string, bindArgs?: Array&lt;ValueType&gt;):Promise&lt;ResultSet&gt; | Queries data in the RDB store using the specified SQL statement. This method uses a promise to return the result.<br>- **sql**: SQL statement.<br>- **bindArgs**: arguments in the SQL statement.|
| RdbStore | query(rdbPredicates: RdbPredicates, columns: Array, callback: AsyncCallback&lt;ResultSet&gt;): void | Queries data in the RDB store based on the specified **RdbPredicates** object. This API uses a callback to return the result.<br>- **rdbPredicates**: conditions for querying data.<br>- **columns**: columns to query. If this parameter is not specified, the query applies to all columns.<br>- **callback**: callback invoked to return the result. If the operation is successful, a **ResultSet** object will be returned.|
| RdbStore | query(rdbPredicates: RdbPredicates, columns: Array): Promise&lt;ResultSet&gt; | Queries data in the RDB store based on the specified **RdbPredicates** object. This API uses a promise to return the result.<br>- **rdbPredicates**: conditions for querying data.<br>- **columns**: columns to query. If this parameter is not specified, the query applies to all columns.|
| RdbStore | querySql(sql: string, bindArgs: Array&lt;ValueType&gt;, callback: AsyncCallback&lt;ResultSet&gt;):void | Queries data in the RDB store using the specified SQL statement. This API uses a callback to return the result.<br>- **sql**: SQL statement.<br>- **bindArgs**: arguments in the SQL statement.<br>- **callback**: callback invoked to return the result. If the operation is successful, a **ResultSet** object will be returned.|
| RdbStore | querySql(sql: string, bindArgs?: Array&lt;ValueType&gt;):Promise&lt;ResultSet&gt; | Queries data in the RDB store using the specified SQL statement. This API uses a promise to return the result.<br>- **sql**: SQL statement.<br>- **bindArgs**: arguments in the SQL statement.|
### Using Predicates
......@@ -148,8 +148,8 @@ A result set can be regarded as a row of data in the queried results. It allows
| Class| API| Description|
| -------- | -------- | -------- |
| RdbStore | setDistributedTables(tables: Array\<string>, callback: AsyncCallback\<void>): void; | Sets a list of distributed tables. This method uses a callback to return the result.<br>- **tables**: names of the distributed tables to set.<br>- **callback**: callback invoked to return the result.|
| RdbStore | setDistributedTables(tables: Array\<string>): Promise\<void>; | Sets a list of distributed tables. This method uses a promise to return the result.<br>- **tables**: names of the distributed tables to set.|
| RdbStore | setDistributedTables(tables: Array\<string>, callback: AsyncCallback\<void>): void; | Sets a list of distributed tables. This API uses a callback to return the result.<br>- **tables**: names of the distributed tables to set.<br>- **callback**: callback invoked to return the result.|
| RdbStore | setDistributedTables(tables: Array\<string>): Promise\<void>; | Sets a list of distributed tables. This API uses a promise to return the result.<br>- **tables**: names of the distributed tables to set.|
**Obtaining the Distributed Table Name for a Remote Device**
......@@ -159,8 +159,8 @@ You can obtain the distributed table name for a remote device based on the local
| Class| API| Description|
| -------- | -------- | -------- |
| RdbStore | obtainDistributedTableName(device: string, table: string, callback: AsyncCallback\<string>): void; | Obtains the distributed table name for a remote device based on the local table name. The distributed table name is required when the database of a remote device is queried. This API uses an asynchronous callback to return the result.<br>- **device**: remote device.<br>- **table**: local table name.<br>- **callback**: callback used to return the result. If the operation is successful, the distributed table name of the remote device will be returned.|
| RdbStore | obtainDistributedTableName(device: string, table: string): Promise\<string>; | Obtains the distributed table name for a remote device based on the local table name. The distributed table name is used to query the RDB store of the remote device. This method uses a promise to return the result.<br>- **device**: remote device.<br>- **table**: local table name.|
| RdbStore | obtainDistributedTableName(device: string, table: string, callback: AsyncCallback\<string>): void; | Obtains the distributed table name for a remote device based on the local table name. The distributed table name is required when the database of a remote device is queried. This API uses an asynchronous callback to return the result.<br>- **device**: remote device.<br>- **table**: local table name.<br>- **callback**: callback used to return the result. If the operation is successful, the distributed table name of the remote device will be returned.|
| RdbStore | obtainDistributedTableName(device: string, table: string): Promise\<string>; | Obtains the distributed table name for a remote device based on the local table name. The distributed table name is used to query the RDB store of the remote device. This API uses a promise to return the result.<br>- **device**: remote device.<br>- **table**: local table name.|
**Synchronizing Data Between Devices**
......@@ -168,8 +168,8 @@ You can obtain the distributed table name for a remote device based on the local
| Class| API| Description|
| -------- | -------- | -------- |
| RdbStore | sync(mode: SyncMode, predicates: RdbPredicates, callback: AsyncCallback<Array<[string, number]>>): void;| Synchronizes data between devices. This method uses a callback to return the result.<br>- **mode**: data synchronization mode. **SYNC\_MODE\_PUSH** means to push data from the local device to a remote device. **SYNC\_MODE\_PULL** means to pull data from a remote device to the local device.<br>- **predicates**: data and devices to be synchronized.<br>- **callback**: callback invoked to return the result. In the result, **string** indicates the device ID, and **number** indicates the synchronization status of each device. The value **0** indicates a success, and other values indicate a failure.|
| RdbStore | sync(mode: SyncMode, predicates: RdbPredicates): Promise<Array<[string, number]>>;| Synchronizes data between devices. This method uses a promise to return the result.<br>- **mode**: data synchronization mode. **SYNC\_MODE\_PUSH** means to push data from the local device to a remote device. **SYNC\_MODE\_PULL** means to pull data from a remote device to the local device.<br>- **predicates**: data and devices to be synchronized. |
| RdbStore | sync(mode: SyncMode, predicates: RdbPredicates, callback: AsyncCallback<Array<[string, number]>>): void;| Synchronizes data between devices. This API uses a callback to return the result.<br>- **mode**: data synchronization mode. **SYNC_MODE_PUSH** means to push data from the local device to a remote device. **SYNC_MODE_PULL** means to pull data from a remote device to the local device.<br>- **predicates**: data and devices to be synchronized.<br>- **callback**: callback invoked to return the result. In the result, **string** indicates the device ID, and **number** indicates the synchronization status of each device. The value **0** indicates a success, and other values indicate a failure.|
| RdbStore | sync(mode: SyncMode, predicates: RdbPredicates): Promise<Array<[string, number]>>;| Synchronizes data between devices. This API uses a promise to return the result.<br>- **mode**: data synchronization mode. **SYNC_MODE_PUSH** means to push data from the local device to a remote device. **SYNC_MODE_PULL** means to pull data from a remote device to the local device.<br>- **predicates**: data and devices to be synchronized. |
**Registering an RDB Store Observer**
......@@ -177,7 +177,7 @@ You can obtain the distributed table name for a remote device based on the local
| Class| API| Description|
| -------- | -------- | -------- |
| RdbStore |on(event: 'dataChange', type: SubscribeType, observer: Callback<Array\<string>>): void;| Registers an observer for this RDB store to subscribe to distributed data changes. When data in the RDB store changes, a callback will be invoked to return the data changes.<br>- **type**: subscription type. **SUBSCRIBE\_TYPE\_REMOTE** means to subscribe to remote data changes.<br>- **observer**: observer that listens for data changes in the RDB store.|
| RdbStore |on(event: 'dataChange', type: SubscribeType, observer: Callback<Array\<string>>): void;| Registers an observer for this RDB store to subscribe to distributed data changes. When data in the RDB store changes, a callback will be invoked to return the data changes.<br>- **type**: subscription type. **SUBSCRIBE_TYPE_REMOTE** means to subscribe to remote data changes.<br>- **observer**: observer that listens for data changes in the RDB store.|
**Unregistering an RDB Store Observer**
......@@ -185,7 +185,7 @@ You can obtain the distributed table name for a remote device based on the local
| Class| API| Description|
| -------- | -------- | -------- |
| RdbStore |off(event:'dataChange', type: SubscribeType, observer: Callback<Array\<string>>): void;| Unregisters the observer of the specified type for the RDB store. This API uses a callback to return the result.<br>- **type**: subscription type. **SUBSCRIBE\_TYPE\_REMOTE** means to subscribe to remote data changes.<br>- **observer**: observer to unregister.|
| RdbStore |off(event:'dataChange', type: SubscribeType, observer: Callback<Array\<string>>): void;| Unregisters the observer of the specified type for the RDB store. This API uses a callback to return the result.<br>- **type**: subscription type. **SUBSCRIBE_TYPE_REMOTE** means to subscribe to remote data changes.<br>- **observer**: observer to unregister.|
## How to Develop
......@@ -193,7 +193,7 @@ You can obtain the distributed table name for a remote device based on the local
1. Create an RDB store.
1. Configure the RDB store attributes, including the RDB store name, storage mode, and whether read-only mode is used.
2. Initialize the table structure and related data in the RDB store.
3. Create the RDB store.
3. Create an RDB store.
The sample code is as follows:
......@@ -258,7 +258,7 @@ You can obtain the distributed table name for a remote device based on the local
```
5. Synchronize data across devices.
1. Constructs an **RdbPredicates** object to specify remote devices within the network to be synchronized.
1. Construct an **RdbPredicates** object to specify remote devices within the network to be synchronized.
2. Call the **sync()** method to synchronize data.
3. Check whether the data synchronization is successful.
......
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