js-apis-service-extension-ability.md

# ServiceExtensionAbility

> **NOTE**<br/>
> The initial APIs of this module are supported since API version 9. Newly added APIs will be marked with a superscript to indicate their earliest API version.


Provides APIs related to **ServiceExtension**.


## Modules to Import

```
import ServiceExtension from '@ohos.application.ServiceExtensionAbility';
```


## Required Permissions

None.


## Attributes

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

| Name| Type| Readable| Writable| Description|
| -------- | -------- | -------- | -------- | -------- |
| context | [ServiceExtensionContext](js-apis-service-extension-context.md)  | Yes| No| Service extension context, which is inherited from **ExtensionContext**.|


## ServiceExtensionAbility.onCreate

onCreate(want: Want): void;

Called when an extension is created to initialize the service logic.

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| want |  [Want](js-apis-application-Want.md) | Yes| Information related to this extension, including the ability name and bundle name.|

**Example**

  ```js
  class ServiceExt extends ServiceExtension {
    onCreate(want) {
      console.log('onCreate, want:' + want.abilityName);
    }
  }
  ```


## ServiceExtensionAbility.onDestroy

onDestroy(): void;

Called when this extension is destroyed to clear resources.

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**Example**

  ```js
  class ServiceExt extends ServiceExtension {
    onDestroy() {
      console.log('onDestroy');
    }
  }
  ```


## ServiceExtensionAbility.onRequest

onRequest(want: Want, startId: number): void;

Called after **onCreate** is invoked when an ability is started by calling **startAbility**. The value of **startId** is incremented for each ability that is started.

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| want |  [Want](js-apis-application-Want.md) | Yes| Information related to this extension, including the ability name and bundle name.|
| startId | number | Yes| Number of ability start times. The initial value is **1**, and the value is automatically incremented for each ability started.|

**Example**

  ```js
  class ServiceExt extends ServiceExtension {
    onRequest(want, startId) {
      console.log('onRequest, want:' + want.abilityName);
    }
  }
  ```


## ServiceExtensionAbility.onConnect

onConnect(want: Want): rpc.RemoteObject;

Called after **onCreate** is invoked when an ability is started by calling **connectAbility**. A **RemoteObject** object is returned for communication with the client.

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| want |  [Want](js-apis-application-Want.md)| Yes| Information related to this extension, including the ability name and bundle name.|

**Return value**

| Type| Description|
| -------- | -------- |
| rpc.RemoteObject | A **RemoteObject** object used for communication with the client.|

**Example**

  ```js
  import rpc from '@ohos.rpc'
  class StubTest extends rpc.RemoteObject{
      constructor(des) {
          super(des);
      }
      onConnect(code, data, reply, option) {
      }
  }
  class ServiceExt extends ServiceExtension {
    onConnect(want) {
      console.log('onConnect , want:' + want.abilityName);
      return new StubTest("test");
    }
  }
  ```


## ServiceExtensionAbility.onDisconnect

onDisconnect(want: Want): void;

Called when the ability is disconnected.

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| want |[Want](js-apis-application-Want.md)| Yes| Information related to this extension, including the ability name and bundle name.|

**Example**

  ```js
  class ServiceExt extends ServiceExtension {
    onDisconnect(want) {
      console.log('onDisconnect, want:' + want.abilityName);
    }
  }
  ```