reference/apis-distributedservice-kit/js-apis-link-enhance.md

# @ohos.distributedsched.linkEnhance (Enhanced Connection)
<!--Kit: Distributed Service Kit-->
<!--Subsystem: DistributedSched-->
<!--Owner: @wangJE-->
<!--Designer: @lee_jet520-->
<!--Tester: @Ytt-test-->
<!--Adviser: @w_Machine_cc-->
The **linkEnhance** module delivers highly efficient Bluetooth connectivity and data transmission capabilities, significantly enhancing the cross-device connection stability. By employing a multi-channel merging algorithm, it not only increases the number of available cross-device connections but also strengthens cross-device data transmission capabilities, thereby improving the overall user experience.

> **NOTE**
>
> The initial APIs of this module are supported since API version 20. Newly added APIs will be marked with a superscript to indicate their earliest API version.

## Modules to Import

```js
import { linkEnhance } from '@kit.DistributedServiceKit';
```

## linkEnhance.createServer

createServer(name:&nbsp;string):&nbsp;Server

Creates a **Server** object. After **start()** is called, the device can be connected to other devices as a server.

**Required permissions**: ohos.permission.DISTRIBUTED_DATASYNC

**System capability**: SystemCapability.DistributedSched.AppCollaboration

**Parameters**

| Name      | Type                                      | Mandatory  | Description      |
| --------- | ---------------------------------------- | ---- | -------- |
| name | string  | Yes   | **Server** object name. The value is a string of up to 255 bytes. It cannot be empty. |

**Returns**

| Type                 | Description              |
| ------------------- | ---------------- |
| [Server](#server) | **Server** object created.|

**Error codes**

For details about the error codes, see [Enhanced Connection Error Codes](errorcode_linkEnhance.md).

| ID| Error Message|
| ------- | -------------------------------- |
| 201      | Permission denied.|
| 32390203      | Duplicate server name.|
| 32390206 | Invalid parameter.  |

**Example**

```ts
import { linkEnhance } from '@kit.DistributedServiceKit';
import { BusinessError } from '@kit.BasicServicesKit';
import { hilog } from '@kit.PerformanceAnalysisKit';
const TAG = "testDemo";

try {
  let name:string = "demo";
  hilog.info(0x0000, TAG, 'start sever name = ' + name);
  // Construct a Server object using the specified name.
  let server: linkEnhance.Server = linkEnhance.createServer(name);
} catch (err) {
  hilog.info(0x0000, TAG, 'start sever errCode: ' + (err as BusinessError).code + ', errMessage: ' +
  (err as BusinessError).message);
}
```

## linkEnhance.createConnection

createConnection(deviceId:&nbsp;string,&nbsp;name:&nbsp;string):&nbsp;Connection

Creates a **Connection** object on the device that functions as the client. The device can then initiate connection requests to the device that functions as the server.

**Required permissions**: ohos.permission.DISTRIBUTED_DATASYNC

**System capability**: SystemCapability.DistributedSched.AppCollaboration

**Parameters**

| Name      | Type                                     | Mandatory  | Description       |
| --------- | --------------------------------------- | ---- | --------- |
| deviceId  | string | Yes   | Device ID of the peer device, that is, the BLE MAC address of the peer device. For details about how to obtain the BLE MAC address, see [BLE Advertising and Scanning](../../connectivity/bluetooth/ble-development-guide.md).|
| name      | string | Yes   | Server name of the device to be connected. The value is a string of up to 255 bytes. It cannot be empty.|

**Returns**

| Type                 | Description              |
| ------------------- | ---------------- |
| [Connection](#connection) | **Connection** object created.|

**Error codes**

For details about the error codes, see [Enhanced Connection Error Codes](errorcode_linkEnhance.md).

| ID| Error Message|
| ------- | -------------------------------- |
| 201      | Permission denied.|
| 32390206 | Invalid parameter.  |

**Example**

 On the device that functions as the client, call the **createConnection()** to create a **Connection** object.

```ts
import { linkEnhance } from '@kit.DistributedServiceKit';
import { BusinessError } from '@kit.BasicServicesKit';
import { hilog } from '@kit.PerformanceAnalysisKit';
const TAG = "testDemo";

try {
  let peerDeviceId: string = "00:11:22:33:44:55";
  hilog.info(0x0000, TAG, 'connection sever deviceId = ' + peerDeviceId);
  let connection: linkEnhance.Connection = linkEnhance.createConnection(peerDeviceId, "demo");
} catch (err) {
  hilog.info(0x0000, TAG, 'errCode: ' + (err as BusinessError).code + ', errMessage: ' +
  (err as BusinessError).message);
}
```
## Server

Represents a **Server** object, which provides methods for starting, stopping, and closing the server, and registering or unregistering event callbacks.

The following APIs are used on the server.

### start()

start():&nbsp;void

Starts a server so that it can be connected by the client. A maximum of 10 servers are supported.

**Required permissions**: ohos.permission.DISTRIBUTED_DATASYNC

**System capability**: SystemCapability.DistributedSched.AppCollaboration

**Error codes**

For details about the error codes, see [Enhanced Connection Error Codes](errorcode_linkEnhance.md).

| ID| Error Message|
| ------- | -------------------------------- |
| 201      | Permission denied.|
| 32390202 | The number of servers exceeds the limit. |
| 32390300 | Internal error. |

**Example**

```ts
import { linkEnhance } from '@kit.DistributedServiceKit';
import { BusinessError } from '@kit.BasicServicesKit';
import { hilog } from '@kit.PerformanceAnalysisKit';
const TAG = "testDemo";

try {
  let name: string = "demo";
  hilog.info(0x0000, TAG, 'start sever name = ' + name);
  let server: linkEnhance.Server = linkEnhance.createServer(name);
  server.start();
} catch (err) {
  hilog.error(0x0000, TAG, 'start sever errCode: ' + (err as BusinessError).code + ', errMessage: ' +
  (err as BusinessError).message);
}
```
### stop()

stop():&nbsp;void

Stops the server. After the server is stopped, you can call `start` to start it again.

**Required permissions**: ohos.permission.DISTRIBUTED_DATASYNC

**System capability**: SystemCapability.DistributedSched.AppCollaboration

**Error codes**

For details about the error codes, see [Enhanced Connection Error Codes](errorcode_linkEnhance.md).

| ID| Error Message|
| ------- | -------------------------------- |
| 201      | Permission denied.|

**Example**

```ts
import { linkEnhance } from '@kit.DistributedServiceKit';
import { BusinessError } from '@kit.BasicServicesKit';
import { hilog } from '@kit.PerformanceAnalysisKit';
const TAG = "testDemo";

try {
  let name: string = "demo";
  hilog.info(0x0000, TAG, 'start sever name = ' + name);
  let server: linkEnhance.Server = linkEnhance.createServer(name);
  server.start();
  server.stop();
} catch (err) {
  hilog.error(0x0000, TAG, 'start sever errCode: ' + (err as BusinessError).code + ', errMessage: ' +
  (err as BusinessError).message);
}
```

### close()

close():&nbsp;void

Destroys the **Server** object to release related resources. To interact with the peer device again, create a new **Server** object.

**Required permissions**: ohos.permission.DISTRIBUTED_DATASYNC

**System capability**: SystemCapability.DistributedSched.AppCollaboration

**Error codes**

For details about the error codes, see [Enhanced Connection Error Codes](errorcode_linkEnhance.md).

| ID| Error Message|
| ------- | -------------------------------- |
| 201      | Permission denied.|

**Example**

```ts
import { linkEnhance } from '@kit.DistributedServiceKit';
import { BusinessError } from '@kit.BasicServicesKit';
import { hilog } from '@kit.PerformanceAnalysisKit';
const TAG = "testDemo";

try {
  let name: string = "demo";
  hilog.info(0x0000, TAG, 'start sever name = ' + name);
  let server: linkEnhance.Server = linkEnhance.createServer(name);
  server.start();
  server.close();
} catch (err) {
  hilog.error(0x0000, TAG, 'start sever errCode: ' + (err as BusinessError).code + ', errMessage: ' +
  (err as BusinessError).message);
}
```
### on('connectionAccepted')

on(type: 'connectionAccepted', callback: Callback&lt;Connection&gt;): void

Registers a callback listener for **connectionAccepted** events. This API uses an asynchronous callback to return the result.

**Required permissions**: ohos.permission.DISTRIBUTED_DATASYNC

**System capability**: SystemCapability.DistributedSched.AppCollaboration

| Name      | Type                                   | Mandatory  | Description   |
| --------- | ------------------------------------- | ---- | ----- |
| type | string  | Yes   |   Event type, which is **connectionAccepted**. This event is triggered when a connection from the peer end is received.  |
| callback | Callback&lt;[Connection](#connection)&gt; | Yes   | Registered callback, which is used to return the [Connection](#connection) object.|

**Error codes**

For details about the error codes, see [Enhanced Connection Error Codes](errorcode_linkEnhance.md).

| ID| Error Message|
| ------- | -------------------------------- |
| 201      | Permission denied.|
| 32390206 | Parameter invalid.  |

**Example**

```ts
import { linkEnhance } from '@kit.DistributedServiceKit';
import { BusinessError } from '@kit.BasicServicesKit';
import { hilog } from '@kit.PerformanceAnalysisKit';
const TAG = "testDemo";

try {
  let name: string = "demo";
  hilog.info(0x0000, TAG, 'start sever name = ' + name);
  // Construct a Server object using the specified name.
  let server: linkEnhance.Server = linkEnhance.createServer(name);

  // Subscribe to connectionAccepted events.
  server.on('connectionAccepted', (connection: linkEnhance.Connection): void => {
      hilog.info(0x0000, TAG, 'serverOnCallback = ' + JSON.stringify(connection));
  });
  // Start the server.
  server.start();
} catch (err) {
  hilog.info(0x0000, TAG, 'start sever errCode: ' + (err as BusinessError).code + ', errMessage: ' +
  (err as BusinessError).message);
}
```
### off('connectionAccepted')

off(type: 'connectionAccepted', callback?: Callback&lt;Connection&gt;): void

Unregisters the callback listener for **connectionAccepted** events. This API uses an asynchronous callback to return the result.

**Required permissions**: ohos.permission.DISTRIBUTED_DATASYNC

**System capability**: SystemCapability.DistributedSched.AppCollaboration

| Name      | Type                                   | Mandatory  | Description   |
| --------- | ------------------------------------- | ---- | ----- |
| type | string  | Yes   |   Event type, which is **connectionAccepted**. This event is triggered when a connection from the peer end is received.  |
| callback | Callback&lt;[Connection](#connection)&gt; | No   | Registered callback, which is used to return the [Connection](#connection) object.|

**Error codes**

For details about the error codes, see [Enhanced Connection Error Codes](errorcode_linkEnhance.md).

| ID| Error Message|
| ------- | -------------------------------- |
| 201      | Permission denied.|
| 32390206 | Parameter invalid.  |

**Example**

```ts
import { linkEnhance } from '@kit.DistributedServiceKit';
import { BusinessError } from '@kit.BasicServicesKit';
import { hilog } from '@kit.PerformanceAnalysisKit';
const TAG = "testDemo";

try {
  let name: string = "demo";
  hilog.info(0x0000, TAG, 'start sever name = ' + name);
  // Construct a Server object using the specified name.
  let server: linkEnhance.Server = linkEnhance.createServer(name);
  server.on('connectionAccepted', (connection: linkEnhance.Connection): void => {
    hilog.info(0x0000, TAG, 'accpet new connection');
  });
  // Unsubscribe from connectionAccepted events.
  server.off('connectionAccepted', (connection: linkEnhance.Connection): void => {
    hilog.info(0x0000, TAG, 'accpet new connection');
  });
} catch (err) {
  hilog.error(0x0000, TAG, 'start sever errCode: ' + (err as BusinessError).code + ', errMessage: ' +
  (err as BusinessError).message);
}
```

### on('serverStopped')

on(type: 'serverStopped', callback: Callback&lt;number&gt;): void

Registers a callback listener for **serverStopped** events. This API uses an asynchronous callback to return the result.

**Required permissions**: ohos.permission.DISTRIBUTED_DATASYNC

**System capability**: SystemCapability.DistributedSched.AppCollaboration

| Name      | Type                                   | Mandatory  | Description   |
| --------- | ------------------------------------- | ---- | ----- |
| type | string  | Yes   |   Event type, which is **serverStopped**. This event is triggered when the server is stopped abnormally.  |
| callback | Callback&lt;number&gt; | Yes   | Registered callback, where **number** indicates the returned error code.|

**Error codes**

For details about the error codes, see [Enhanced Connection Error Codes](errorcode_linkEnhance.md).

| ID| Error Message|
| ------- | -------------------------------- |
| 201      | Permission denied.|
| 32390206 | Parameter invalid.  |

**Example**

```ts
import { linkEnhance } from '@kit.DistributedServiceKit';
import { BusinessError } from '@kit.BasicServicesKit';
import { hilog } from '@kit.PerformanceAnalysisKit';
const TAG = "testDemo";

try {
  let name: string = "demo";
  hilog.info(0x0000, TAG, 'start sever name = ' + name);
  // Construct a Server object using the specified name.
  let server: linkEnhance.Server = linkEnhance.createServer(name);

  // Unsubscribe from serverStopped events.
  server.on('serverStopped', (reason: number): void => {
    hilog.info(0x0000, TAG, 'serverStopped, reason= ' + reason);
  });
  // Start the server.
  server.start();
} catch (err) {
  hilog.error(0x0000, TAG, 'start sever errCode: ' + (err as BusinessError).code + ', errMessage: ' +
  (err as BusinessError).message);
}
```

### off('serverStopped')

off(type: 'serverStopped', callback?: Callback&lt;number&gt;): void

Unregisters the callback listener for **serverStopped** events. This API uses an asynchronous callback to return the result.

**Required permissions**: ohos.permission.DISTRIBUTED_DATASYNC

**System capability**: SystemCapability.DistributedSched.AppCollaboration

| Name      | Type                                   | Mandatory  | Description   |
| --------- | ------------------------------------- | ---- | ----- |
| type | string  | Yes   |   Event type, which is **serverStopped**. This event is triggered when the server is stopped abnormally.  |
| callback | Callback&lt;number&gt; | No   | Registered callback, where **number** indicates the returned error code.|

**Error codes**

For details about the error codes, see [Enhanced Connection Error Codes](errorcode_linkEnhance.md).

| ID| Error Message|
| ------- | -------------------------------- |
| 201      | Permission denied.|
| 32390206 | Parameter invalid.  |

**Example**

```ts
import { linkEnhance } from '@kit.DistributedServiceKit';
import { BusinessError } from '@kit.BasicServicesKit';
import { hilog } from '@kit.PerformanceAnalysisKit';
const TAG = "testDemo";

try {
  let name: string = "demo";
  hilog.info(0x0000, TAG, 'start sever name = ' + name);
  // Construct a Server object using the specified name.
  let server: linkEnhance.Server = linkEnhance.createServer(name);
  server.on('serverStopped', (reason: number): void => {
    hilog.info(0x0000, TAG, 'serverStopped, reason= ' + reason);
  });
  // Unsubscribe from serverStopped events.
  server.off('serverStopped', (reason: number): void => {
    hilog.info(0x0000, TAG, 'serverStopped, reason= ' + reason);
  });
} catch (err) {
  hilog.info(0x0000, TAG, 'start sever errCode: ' + (err as BusinessError).code + ', errMessage: ' +
  (err as BusinessError).message);
}
```
## ConnectResult

Represents the connection result, which is returned after the client calls **connect()**.

**System capability**: SystemCapability.DistributedSched.AppCollaboration

| **Name**                   | Type      |Read-Only  | Optional  | Description                |
| ----------------- | ------ | ----  | ---- | ------------------ |
| deviceId          | string | No   |No   | ID of the peer device. If the connection is successful, the device ID of the peer device is returned. If the connection fails, an empty string is returned.    |
| success           | boolean | No   |No  | Connection result. The value **true** indicates that the connection is successful, and the value **false** indicates the opposite.|
| reason            | number | No   |No   | Number indicating the result code. If the connection is successful, **0** is returned. If the connection fails, an error code is returned:<br>- 32390200: The client connection times out.<br>- 32390201: The server service is not started.<br>- 32390300: Internal error.<br>For details about the error codes, see [Link Enhancement Error Codes](errorcode_linkEnhance.md).|

## Connection

Represents a **Connection** object, which provides methods for connecting to and disconnecting from a peer device, obtaining the device's ID, sending data, and registering or unregistering event callbacks.

### connect()

connect():&nbsp;void

Connects to the server on the client. A maximum number of 10 connections are supported.

**Required permissions**: ohos.permission.DISTRIBUTED_DATASYNC

**System capability**: SystemCapability.DistributedSched.AppCollaboration


**Error codes**

For details about the error codes, see [Enhanced Connection Error Codes](errorcode_linkEnhance.md).

| ID| Error Message|
| ------- | -------------------------------- |
| 201      | Permission denied.|
| 32390204 | The number of connection exceeds the limit. |
| 32390300 | Internal error. |

**Example**

After creating a **Connection** object, the application on the client device calls **connect()** to connect to the target device (that is, the server).

```ts
import { linkEnhance } from '@kit.DistributedServiceKit';
import { BusinessError } from '@kit.BasicServicesKit';
import { hilog } from '@kit.PerformanceAnalysisKit';
const TAG = "testDemo";

try {
  let peerDeviceId: string = "00:11:22:33:44:55";
  hilog.info(0x0000, TAG, 'connection sever deviceId = ' + peerDeviceId);
  let connection: linkEnhance.Connection = linkEnhance.createConnection(peerDeviceId, "demo");
  // Subscribe to connectResult events.
  connection.on('connectResult', (result: linkEnhance.ConnectResult): void => {
    hilog.info(0x0000, TAG, 'clientConnectResultCallback result = ' + result.success);
  });
  // Initiate a connection.
  connection.connect();
} catch (err) {
  hilog.error(0x0000, TAG, 'errCode: ' + (err as BusinessError).code + ', errMessage: ' +
  (err as BusinessError).message);
}
```

### disconnect()

disconnect():&nbsp;void

Disconnects from the peer device. The created **Connection** object remains valid after this API is called. You can call **connect()** to reconnect to the peer device if necessary.

**Required permissions**: ohos.permission.DISTRIBUTED_DATASYNC

**System capability**: SystemCapability.DistributedSched.AppCollaboration


**Error codes**

For details about the error codes, see [Enhanced Connection Error Codes](errorcode_linkEnhance.md).

| ID| Error Message|
| ------- | -------------------------------- |
| 201      | Permission denied.|

**Example**

```ts
import { linkEnhance } from '@kit.DistributedServiceKit';
import { BusinessError } from '@kit.BasicServicesKit';
import { hilog } from '@kit.PerformanceAnalysisKit';
const TAG = "testDemo";

try {
  let peerDeviceId: string = "00:11:22:33:44:55";
  hilog.info(0x0000, TAG, 'connection sever deviceId = ' + peerDeviceId);
  let connection: linkEnhance.Connection = linkEnhance.createConnection(peerDeviceId, "demo");
  connection.on('connectResult', (result: linkEnhance.ConnectResult): void => {
    hilog.info(0x0000, TAG, 'clientConnectResultCallback result = ' + result.success);
    if (result.success) {
      connection.disconnect();
    }
  });
  connection.connect();
} catch (err) {
    hilog.error(0x0000, TAG, 'errCode: ' + (err as BusinessError).code + ', errMessage: ' +
  (err as BusinessError).message);
}
```

### close()

close():&nbsp;void

Destroys the **Connection** object to release resources. If the device needs to interact with the peer device again, create a **Connection** object again and call `connect()` to initiate a connection.

**Required permissions**: ohos.permission.DISTRIBUTED_DATASYNC

**System capability**: SystemCapability.DistributedSched.AppCollaboration

**Error codes**

For details about the error codes, see [Enhanced Connection Error Codes](errorcode_linkEnhance.md).

| ID| Error Message|
| ------- | -------------------------------- |
| 201      | Permission denied.|


**Example**

```ts
import { linkEnhance } from '@kit.DistributedServiceKit';
import { BusinessError } from '@kit.BasicServicesKit';
import { hilog } from '@kit.PerformanceAnalysisKit';
const TAG = "testDemo";

try {
  let peerDeviceId: string = "00:11:22:33:44:55";
  hilog.info(0x0000, TAG, 'connection sever deviceId = ' + peerDeviceId);
  let connection: linkEnhance.Connection = linkEnhance.createConnection(peerDeviceId, "demo");
  connection.on('connectResult', (result: linkEnhance.ConnectResult): void => {
    hilog.info(0x0000, TAG, 'clientConnectResultCallback result = ' + result.success);
    if (result.success) {
      connection.close();
    }
  });
  connection.connect();
} catch (err) {
  hilog.error(0x0000, TAG, 'errCode: ' + (err as BusinessError).code + ', errMessage: ' +
  (err as BusinessError).message);
}
```
### getPeerDeviceId()

getPeerDeviceId():&nbsp;string

Obtains the device ID of the peer device. This API is called when the connection is established successfully either by initiating a connection or accepting an incoming connection.

**Required permissions**: ohos.permission.DISTRIBUTED_DATASYNC

**System capability**: SystemCapability.DistributedSched.AppCollaboration


**Returns**

| Type                 | Description              |
| ------------------- | ---------------- |
| string | Device ID of the peer device, that is, the BLE MAC address of the peer device. An empty string is returned if no device ID is obtained.|


**Error codes**

For details about the error codes, see [Enhanced Connection Error Codes](errorcode_linkEnhance.md).

| ID| Error Message|
| ------- | -------------------------------- |
| 201      | Permission denied.|

**Example**

```ts
import { linkEnhance } from '@kit.DistributedServiceKit';
import { BusinessError } from '@kit.BasicServicesKit';
import { hilog } from '@kit.PerformanceAnalysisKit';
const TAG = "testDemo";

try {
  let peerDeviceId: string = "00:11:22:33:44:55";
  hilog.info(0x0000, TAG, 'connection sever deviceId = ' + peerDeviceId);
  let connection: linkEnhance.Connection = linkEnhance.createConnection(peerDeviceId, "demo");
  connection.getPeerDeviceId();
  hilog.info(0x0000, TAG, "peerDeviceId=%{public}s" + connection.getPeerDeviceId());
} catch (err) {
  hilog.error(0x0000, TAG, 'errCode: ' + (err as BusinessError).code + ', errMessage: ' +
  (err as BusinessError).message);
}
```

### sendData()

sendData(data:&nbsp;ArrayBuffer):&nbsp;void

Sends data to the server after a connection is established successfully. When the server receives the connection callback, it can also send data to the client.

**Required permissions**: ohos.permission.DISTRIBUTED_DATASYNC

**System capability**: SystemCapability.DistributedSched.AppCollaboration

**Parameters**

| Name      | Type                                     | Mandatory  | Description   |
| --------- | --------------------------------------- | ---- | ----- |
| data | [ArrayBuffer](../../arkts-utils/arraybuffer-object.md) | Yes   | Data to send. The maximum length is 1024 bytes.|

**Error codes**

For details about the error codes, see [Enhanced Connection Error Codes](errorcode_linkEnhance.md).

| ID| Error Message|
| ------- | -------------------------------- |
| 201      | Permission denied.|
| 32390205 | Connection is not ready. |
| 32390206 | Invalid parameter.  |
| 32390300 | Internal error. |

**Example**

```ts
import { linkEnhance } from '@kit.DistributedServiceKit';
import { BusinessError } from '@kit.BasicServicesKit';
import { hilog } from '@kit.PerformanceAnalysisKit';
const TAG = "testDemo";

try {
  let peerDeviceId: string = "00:11:22:33:44:55";
  hilog.info(0x0000, TAG, 'connection sever deviceId = ' + peerDeviceId);
  let connection: linkEnhance.Connection = linkEnhance.createConnection(peerDeviceId, "demo");
  connection.on('connectResult', (result: linkEnhance.ConnectResult): void => {
    hilog.info(0x0000, TAG, 'clientConnectResultCallback result = ' + result.success);
    if (result.success) {
      let len = 1;
      let arraybuffer = new ArrayBuffer(len); // Create the data to send.
      connection.sendData(arraybuffer);
      hilog.info(0x0000, TAG, "sendData data connection peerDeviceId=%{public}s" + connection.getPeerDeviceId());
      connection.disconnect();
    }
  });
  connection.connect();
} catch (err) {
  hilog.error(0x0000, TAG, 'errCode: ' + (err as BusinessError).code + ', errMessage: ' +
  (err as BusinessError).message);
}
```

### on('connectResult')

on(type: 'connectResult', callback: Callback&lt;ConnectResult&gt;): void

Registers a listener for **connectResult** events. This API uses an asynchronous callback to return the result.

**Required permissions**: ohos.permission.DISTRIBUTED_DATASYNC

**System capability**: SystemCapability.DistributedSched.AppCollaboration

**Parameters**

| Name      | Type                                   | Mandatory  | Description   |
| --------- | ------------------------------------- | ---- | ----- |
| type | string  | Yes   |   Event type, which is **connectResult**. This event is triggered when `connect()` is called.  |
| callback | Callback&lt;[ConnectResult](#connectresult)&gt; | Yes   | Registered callback.   |

**Error codes**

For details about the error codes, see [Enhanced Connection Error Codes](errorcode_linkEnhance.md).

| ID| Error Message|
| ------- | -------------------------------- |
| 201      | Permission denied.|
| 32390206 | Invalid parameter.|

**Example**

```ts
import { linkEnhance } from '@kit.DistributedServiceKit';
import { BusinessError } from '@kit.BasicServicesKit';
import { hilog } from '@kit.PerformanceAnalysisKit';
const TAG = "testDemo";

try {
  let peerDeviceId: string = "00:11:22:33:44:55";
  hilog.info(0x0000, TAG, 'connection sever deviceId = ' + peerDeviceId);
  let connection: linkEnhance.Connection = linkEnhance.createConnection(peerDeviceId, "demo");
  // Subscribe to connectResult events.
  connection.on('connectResult', (result: linkEnhance.ConnectResult): void => {
      hilog.info(0x0000, TAG, 'clientConnectResultCallback result = ' + result.success);
  });

  // Initiate a connection.
  connection.connect();
} catch (err) {
  hilog.error(0x0000, TAG, 'errCode: ' + (err as BusinessError).code + ', errMessage: ' +
  (err as BusinessError).message);
}
```

### off('connectResult')

off(type: 'connectResult', callback?: Callback&lt;ConnectResult&gt;): void

Unregisters the listener for **connectResult** events.

**Required permissions**: ohos.permission.DISTRIBUTED_DATASYNC

**System capability**: SystemCapability.DistributedSched.AppCollaboration

**Parameters**

| Name      | Type                                   | Mandatory  | Description   |
| --------- | ------------------------------------- | ---- | ----- |
| type | string  | Yes   |   Event type, which is **connectResult**. This event is triggered when `connect()` is called.  |
| callback | Callback&lt;[ConnectResult](#connectresult)&gt; | No   | Registered callback.   |

**Error codes**

For details about the error codes, see [Enhanced Connection Error Codes](errorcode_linkEnhance.md).

| ID| Error Message|
| ------- | -------------------------------- |
| 201      | Permission denied.|
| 32390206 | Invalid parameter. |

**Example**

```ts
import { linkEnhance } from '@kit.DistributedServiceKit';
import { BusinessError } from '@kit.BasicServicesKit';
import { hilog } from '@kit.PerformanceAnalysisKit';
const TAG = "testDemo";

try {
  let peerDeviceId: string = "00:11:22:33:44:55";
  hilog.info(0x0000, TAG, 'connection sever deviceId = ' + peerDeviceId);
  let connection: linkEnhance.Connection = linkEnhance.createConnection(peerDeviceId, "demo");
  connection.on('connectResult', (result: linkEnhance.ConnectResult): void => {
    hilog.info(0x0000, TAG, 'clientConnectResultCallback result = ' + result.success);
  });
  // Unsubscribe from connectResult events.
  connection.off('connectResult', (result: linkEnhance.ConnectResult): void => {
    hilog.info(0x0000, TAG, 'clientConnectResultCallback result = ' + result.success);
  });
} catch (err) {
  hilog.error(0x0000, TAG, 'errCode: ' + (err as BusinessError).code + ', errMessage: ' +
  (err as BusinessError).message);
}
```

### on('disconnected')

on(type: 'disconnected', callback: Callback&lt;number&gt;): void

Registers a listener for **disconnected** events. This API uses an asynchronous callback to return the result.

**Required permissions**: ohos.permission.DISTRIBUTED_DATASYNC

**System capability**: SystemCapability.DistributedSched.AppCollaboration

**Parameters**

| Name      | Type                                   | Mandatory  | Description   |
| --------- | ------------------------------------- | ---- | ----- |
| type | string  | Yes   |   Event type, which is **disconnected**. This event is triggered when the connection is passively terminated or encounters an exception.  |
| callback | Callback&lt;number&gt; | Yes   | Registered callback, where **number** indicates the returned error code. |

**Error codes**

For details about the error codes, see [Enhanced Connection Error Codes](errorcode_linkEnhance.md).

| ID| Error Message|
| ------- | -------------------------------- |
| 201      | Permission denied.|
| 32390206 | Invalid parameter.|

**Example**

```ts
import { linkEnhance } from '@kit.DistributedServiceKit';
import { BusinessError } from '@kit.BasicServicesKit';
import { hilog } from '@kit.PerformanceAnalysisKit';
const TAG = "testDemo";

try {
  let peerDeviceId: string = "00:11:22:33:44:55";
  hilog.info(0x0000, TAG, 'connection sever deviceId = ' + peerDeviceId);
  let connection: linkEnhance.Connection = linkEnhance.createConnection(peerDeviceId, "demo");
  // Subscribe to disconnected events.
  connection.on('disconnected', (number: number)=> {
      hilog.info(0x0000, TAG, 'connection disconnected reason = ' + number);
  });
} catch (err) {
  hilog.info(0x0000, TAG, 'errCode: ' + (err as BusinessError).code + ', errMessage: ' +
  (err as BusinessError).message);
}
```

### off('disconnected')

off(type: 'disconnected', callback?: Callback&lt;number&gt;): void

Unregisters the listener for **disconnected** events. This API uses an asynchronous callback to return the result.

**Required permissions**: ohos.permission.DISTRIBUTED_DATASYNC

**System capability**: SystemCapability.DistributedSched.AppCollaboration

**Parameters**

| Name      | Type                                   | Mandatory  | Description   |
| --------- | ------------------------------------- | ---- | ----- |
| type | string  | Yes   |   Event type, which is **disconnected**. This event is triggered when the connection is passively terminated or encounters an exception.  |
| callback | Callback&lt;number&gt; | No  | Registered callback, where **number** indicates the returned error code.  |

**Error codes**

For details about the error codes, see [Enhanced Connection Error Codes](errorcode_linkEnhance.md).

| ID| Error Message|
| ------- | -------------------------------- |
| 201      | Permission denied.|
| 32390206 | Invalid parameter. |

**Example**

```ts
import { linkEnhance } from '@kit.DistributedServiceKit';
import { BusinessError } from '@kit.BasicServicesKit';
import { hilog } from '@kit.PerformanceAnalysisKit';
const TAG = "testDemo";

try {
  let peerDeviceId: string = "00:11:22:33:44:55";
  hilog.info(0x0000, TAG, 'connection sever deviceId = ' + peerDeviceId);
  let connection: linkEnhance.Connection = linkEnhance.createConnection(peerDeviceId, "demo");
  connection.on('disconnected', (number: number)=> {
      hilog.info(0x0000, TAG, 'connection disconnected reason = ' + number);
  });
  // Unsubscribe from disconnected events.
  connection.off('disconnected', (number: number)=> {
      hilog.info(0x0000, TAG, 'connection disconnected reason = ' + number);
  });
} catch (err) {
  hilog.error(0x0000, TAG, 'errCode: ' + (err as BusinessError).code + ', errMessage: ' +
  (err as BusinessError).message);
}
```

### on('dataReceived')

on(type: 'dataReceived', callback: Callback&lt;ArrayBuffer&gt;): void

Registers a listener for the **dataReceived** events. This API uses an asynchronous callback to return the result.

**Required permissions**: ohos.permission.DISTRIBUTED_DATASYNC

**System capability**: SystemCapability.DistributedSched.AppCollaboration

**Parameters**

| Name      | Type                                   | Mandatory  | Description   |
| --------- | ------------------------------------- | ---- | ----- |
| type | string  | Yes   |   Event type, which is **dataReceived**. This event is triggered when data is received.  |
| callback | Callback&lt;[ArrayBuffer](../../arkts-utils/arraybuffer-object.md)&gt; | Yes   | Registered callback.|

**Error codes**

For details about the error codes, see [Enhanced Connection Error Codes](errorcode_linkEnhance.md).

| ID| Error Message|
| ------- | -------------------------------- |
| 201      | Permission denied.|
| 32390206 | Invalid parameter.  |

**Example**

```ts
import { linkEnhance } from '@kit.DistributedServiceKit';
import { BusinessError } from '@kit.BasicServicesKit';
import { hilog } from '@kit.PerformanceAnalysisKit';
const TAG = "testDemo";

try {
  let peerDeviceId: string = "00:11:22:33:44:55";
  hilog.info(0x0000, TAG, 'connection sever deviceId = ' + peerDeviceId);
  let connection: linkEnhance.Connection = linkEnhance.createConnection(peerDeviceId, "demo");
  connection.connect();
  connection.on('dataReceived', (data: ArrayBuffer)=> {
      hilog.info(0x0000, TAG, 'recv dataLen = ' + data.byteLength);
  });
} catch (err) {
  hilog.error(0x0000, TAG, 'errCode: ' + (err as BusinessError).code + ', errMessage: ' +
  (err as BusinessError).message);
}
```
### off('dataReceived')

off(type: 'dataReceived', callback?: Callback&lt;ArrayBuffer&gt;): void

Unregisters the listener for **dataReceived** events.

**Required permissions**: ohos.permission.DISTRIBUTED_DATASYNC

**System capability**: SystemCapability.DistributedSched.AppCollaboration

**Parameters**

| Name      | Type                                   | Mandatory  | Description   |
| --------- | ------------------------------------- | ---- | ----- |
| type | string  | Yes   |   Event type, which is **dataReceived**. This event is triggered when data is received.  |
| callback | Callback&lt;[ArrayBuffer](../../arkts-utils/arraybuffer-object.md)&gt; | No   | Registered callback.|

**Error codes**

For details about the error codes, see [Enhanced Connection Error Codes](errorcode_linkEnhance.md).

| ID| Error Message|
| ------- | -------------------------------- |
| 201      | Permission denied.|
| 32390206 | Invalid parameter.  |

**Example**

```ts
import { linkEnhance } from '@kit.DistributedServiceKit';
import { BusinessError } from '@kit.BasicServicesKit';
import { hilog } from '@kit.PerformanceAnalysisKit';
const TAG = "testDemo";

try {
  let peerDeviceId: string = "00:11:22:33:44:55";
  hilog.info(0x0000, TAG, 'connection sever deviceId = ' + peerDeviceId);
  let connection: linkEnhance.Connection = linkEnhance.createConnection(peerDeviceId, "demo");
  connection.on('dataReceived', (data: ArrayBuffer)=> {
      hilog.info(0x0000, TAG, 'recv dataLen = ' + data.byteLength);
  });
  connection.off('dataReceived', (data: ArrayBuffer)=> {
      hilog.info(0x0000, TAG, 'recv dataLen = ' + data.byteLength);
  });
} catch (err) {
  hilog.error(0x0000, TAG, 'errCode: ' + (err as BusinessError).code + ', errMessage: ' +
  (err as BusinessError).message);
}
```