# NestGateway

**Kind:** Interface

**Source:** [`packages/websockets/interfaces/nest-gateway.interface.ts`](https://github.com/nestjs/nest/blob/master/packages/websockets/interfaces/nest-gateway.interface.ts#L4)

**Part of:** [Websockets](subsystem-packages-websockets)

`NestGateway` defines lifecycle hooks for WebSocket gateway classes in NestJS. Implement these optional methods to access the initialized server, react to client connections, and clean up when clients disconnect.

## Properties

| Property | Type |
|---|---|
| `afterInit` | `(server: any) => void` |
| `handleConnection` | `(...args: any[]) => void` |
| `handleDisconnect` | `(client: any) => void` |

## Diagram

```mermaid
graph LR
  A[WebSocket Server Initialized] --> B[afterInit(server)]
  B --> C[Client Connects]
  C --> D[handleConnection(...args)]
  D --> E[Client Disconnects]
  E --> F[handleDisconnect(client)]
```

## Usage

```ts
import { WebSocketGateway } from '@nestjs/websockets';
import type { NestGateway } from '@nestjs/websockets';

@WebSocketGateway()
export class EventsGateway implements NestGateway {
  afterInit(server: any): void {
    console.log('WebSocket server initialized');
  }

  handleConnection(client: any, ...args: any[]): void {
    console.log(`Client connected: ${client.id}`);
  }

  handleDisconnect(client: any): void {
    console.log(`Client disconnected: ${client.id}`);
  }
}
```

## AI Coding Instructions

- Implement `NestGateway` on classes decorated with `@WebSocketGateway()` when lifecycle callbacks are needed.
- Use `afterInit` to configure or inspect the underlying WebSocket server after it is created.
- Keep `handleConnection(...args)` flexible because adapter-specific connection arguments may follow the client object.
- Release client-specific resources, subscriptions, and session state in `handleDisconnect`.
- Avoid assuming a specific client or server API when supporting multiple WebSocket adapters; narrow `any` values to the adapter type in use.