---
lang: en
title: 'API docs: core.lifecycleobserver'
keywords: LoopBack 4.0, LoopBack 4, Node.js, TypeScript, OpenAPI
sidebar: lb4_sidebar
editurl: https://github.com/loopbackio/loopback-next/tree/master/packages/core
permalink: /doc/en/lb4/apidocs.core.lifecycleobserver.html
---

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[Home](./index.md) &gt; [@loopback/core](./core.md) &gt; [LifeCycleObserver](./core.lifecycleobserver.md)

## LifeCycleObserver interface

Observers to handle life cycle init/start/stop events

<b>Signature:</b>

```typescript
export interface LifeCycleObserver 
```

## Methods

|  Method | Description |
|  --- | --- |
|  [init(injectedArgs)?](./core.lifecycleobserver.init.md) | <i>(Optional)</i> The method to be invoked during <code>init</code>. It will only be called at most once for a given application instance. |
|  [start(injectedArgs)?](./core.lifecycleobserver.start.md) | <i>(Optional)</i> The method to be invoked during <code>start</code> |
|  [stop(injectedArgs)?](./core.lifecycleobserver.stop.md) | <i>(Optional)</i> The method to be invoked during <code>stop</code> |