NestJS Communication & Stakeholder Relations 5

Question 1

Which NestJS mechanism allows a microservice to return data back to the caller in a request-response pattern?

Accepted Answer

Returning a value or Observable from a @MessagePattern() handler

Answer

Returning a value or Observable from a @MessagePattern() handler automatically sends the reply to the requesting service.

Question 2

A DevOps stakeholder asks how to health-check the NestJS service. Which package provides a ready-made /health endpoint?

Accepted Answer

@nestjs/terminus

Answer

@nestjs/terminus integrates with infrastructure health checkers and exposes a configurable /health endpoint.

Question 3

When a NestJS WebSocket client disconnects unexpectedly, which lifecycle hook is called on the gateway?

Accepted Answer

@OnGatewayDisconnect

Answer

Implementing OnGatewayDisconnect and its handleDisconnect() method lets the gateway react when a client drops.

Question 4

A project manager requires all inter-service messages to carry a correlation ID for tracing. Where is the best place to inject this in NestJS?

Accepted Answer

In a global interceptor that wraps every outgoing request

Answer

A global interceptor can attach a correlation ID to every outgoing context before the handler executes.

Question 5

Which property of the @WebSocketGateway() decorator limits connections to a specific namespace in Socket.IO?

Accepted Answer

namespace

Answer

The namespace property in @WebSocketGateway({ namespace: '/chat' }) scopes the gateway to a Socket.IO namespace.

NestJS Practice Test