1# @ohos.app.ability.ChildProcess
2
3**ChildProcess** is the base class for you to customize child processes. When starting a child process through [childProcessManager](js-apis-app-ability-childProcessManager.md), you must inherit this class and override the entrypoint method.
4
5> **NOTE**
6>
7> The initial APIs of this module are supported since API version 11. Newly added APIs will be marked with a superscript to indicate their earliest API version.
8>
9> The APIs of this module can be used only in the stage model.
10
11## Modules to Import
12
13```ts
14import { ChildProcess } from '@kit.AbilityKit';
15```
16
17## ChildProcess.onStart
18
19onStart(args?: ChildProcessArgs): void
20
21Entrypoint method of the child process. This callback is triggered when the child process is started through [childProcessManager](js-apis-app-ability-childProcessManager.md).
22
23**System capability**: SystemCapability.Ability.AbilityRuntime.Core
24
25**Parameters**
26
27  | Name | Type | Mandatory | Description |
28  | -------- | -------- | -------- | -------- |
29  | args<sup>12+</sup> | [ChildProcessArgs](js-apis-app-ability-childProcessArgs.md) | No | Parameters transferred to the child process. |
30
31**Example**
32```ts
33import { ChildProcess, ChildProcessArgs } from '@kit.AbilityKit';
34
35export default class DemoProcess extends ChildProcess {
36
37  onStart(args?: ChildProcessArgs) {
38    let entryParams = args?.entryParams;
39    let fd = args?.fds?.key1;
40    // ..
41  }
42}
43```
44