1# @ohos.app.ability.ChildProcess (Child Process Base Class) 2<!--Kit: Ability Kit--> 3<!--Subsystem: Ability--> 4<!--Owner: @SKY2001--> 5<!--Designer: @jsjzju--> 6<!--Tester: @lixueqing513--> 7<!--Adviser: @huipeizi--> 8 9ChildProcess 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. 10 11> **NOTE** 12> 13> 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. 14> 15> The APIs of this module can be used only in the stage model. 16 17## Modules to Import 18 19```ts 20import { ChildProcess } from '@kit.AbilityKit'; 21``` 22 23## ChildProcess.onStart 24 25onStart(args?: ChildProcessArgs): void 26 27Entrypoint method of the child process. This callback is triggered when the child process is started through [childProcessManager](js-apis-app-ability-childProcessManager.md). 28 29**System capability**: SystemCapability.Ability.AbilityRuntime.Core 30 31**Parameters** 32 33 | Name| Type| Mandatory| Description| 34 | -------- | -------- | -------- | -------- | 35 | args<sup>12+</sup> | [ChildProcessArgs](js-apis-app-ability-childProcessArgs.md) | No| Parameters transferred to the child process.| 36 37**Example** 38```ts 39import { ChildProcess, ChildProcessArgs } from '@kit.AbilityKit'; 40 41export default class DemoProcess extends ChildProcess { 42 43 onStart(args?: ChildProcessArgs) { 44 let entryParams = args?.entryParams; 45 let fd = args?.fds?.key1; 46 // .. 47 } 48} 49``` 50