Can NestJS be used for working with protocols or systems other than HTTP?

Yes, NestJS can be used not only for HTTP but also for working with other protocols and systems. Thanks to its modular architecture and support for various transport layers, NestJS allows creating microservices and applications that use, for example, WebSocket, gRPC, MQTT, TCP, and other protocols.

Example of using WebSocket in NestJS:

import { WebSocketGateway, SubscribeMessage, MessageBody } from '@nestjs/websockets';

@WebSocketGateway()
export class EventsGateway {
  @SubscribeMessage('message')
  handleMessage(@MessageBody() data: string): string {
    return `Received message: ${data}`;
  }
}

Thus, NestJS provides abstractions for working with different transports, which allows using it not only for HTTP services.