# Creating a ServiceAbility


1. Create a ServiceAbility.

    When you create a ServiceAbility in DevEco Studio, DevEco Studio automatically generates the **onStart()**, **onStop()**, and **onCommand()** callbacks. You need to implement the other lifecycle callbacks. You can also implement your own logic to be processed when another ability requests to interact with your ServiceAbility. The sample code is as follows:

    ```ts
    import { Want } from '@kit.AbilityKit';
    import { rpc } from '@kit.IPCKit';
    import { hilog } from '@kit.PerformanceAnalysisKit';

    const TAG: string = '[Sample_FAModelAbilityDevelop]';
    const domain: number = 0xFF00;

    class FirstServiceAbilityStub extends rpc.RemoteObject {
      constructor(des: Object) {
        if (typeof des === 'string') {
          super(des);
        } else {
          return;
        }
      }

      onRemoteRequest(code: number, data: rpc.MessageParcel, reply: rpc.MessageParcel, option: rpc.MessageOption): boolean {
        hilog.info(domain, TAG, 'ServiceAbility onRemoteRequest called');
        if (code === 1) {
          let string = data.readString();
          hilog.info(domain, TAG, `ServiceAbility string=${string}`);
          let result = Array.from(string).sort().join('');
          hilog.info(domain, TAG, `ServiceAbility result=${result}`);
          reply.writeString(result);
        } else {
          hilog.info(domain, TAG, 'ServiceAbility unknown request code');
        }
        return true;
      }
    }

    class ServiceAbility {
      onStart(): void {
        hilog.info(domain, TAG, 'ServiceAbility onStart');
      }

      onStop(): void {
        hilog.info(domain, TAG, 'ServiceAbility onStop');
      }

      onCommand(want: Want, startId: number): void {
        hilog.info(domain, TAG, 'ServiceAbility onCommand');
      }

      onConnect(want: Want): rpc.RemoteObject {
        hilog.info(domain, TAG, 'ServiceAbility onDisconnect' + want);
        return new FirstServiceAbilityStub('test');
      }

      onDisconnect(want: Want): void {
        hilog.info(domain, TAG, 'ServiceAbility onDisconnect' + want);
      }
    }

    export default new ServiceAbility();
    ```

2. Register the ServiceAbility.
   
    Declare the ServiceAbility in the **config.json** file by setting its **type** attribute to **service**. The **visible** attribute specifies whether the ServiceAbility can be called by other applications. The value **true** means that the ServiceAbility can be called by other applications, and **false** means that the ServiceAbility can be called only within the application. To enable the ServiceAbility to be called by other applications, set **visible** to **true** when registering the ServiceAbility and enable associated startup. For details about the startup rules, see [Component Startup Rules](component-startup-rules.md).
    
    ```json
    {
      ...
      "module": {
        ...
        "abilities": [
          ...
          {
            "name": ".ServiceAbility",
            "srcLanguage": "ets",
            "srcPath": "ServiceAbility",
            "icon": "$media:icon",
            "description": "$string:ServiceAbility_desc",
            "type": "service",
            "visible": true
          },
          ...
        ]
        ...
      }
    }
    ```