ServerNats

Kind: Class

Source: packages/microservices/server/server-nats.ts

Part of: Microservices

ServerNats is the NATS transport server implementation for NestJS microservices. It connects to a NATS broker, subscribes registered message handlers to their patterns, routes incoming requests or events to those handlers, and manages connection lifecycle and status updates.

Extends: Server

Methods

Properties

Where it refuses work

• ServerNats stops the work with Error when !this.natsClient — “Not initialized. Please call the "listen"/"startAllMicroservices" method before accessing…”.
• ServerNats stops the work with an early return when !this.natsClient.
• ServerNats stops the work with an early return when error.
• ServerNats stops the work with an early return when isUndefined((message as IncomingRequest).id).
• ServerNats stops the work with an early return when natsMsg.reply.

When something fails

• ServerNats handles failure in 1 place: it logs it and continues in all 1.

Diagram

mermaid
graph LR
  A[Nest Microservice] --> B[ServerNats]
  B --> C[createNatsClient]
  C --> D[NATS Broker]
  B --> E[bindEvents]
  E --> F[Registered Message Handlers]
  D --> G[Incoming NATS Message]
  G --> H[getMessageHandler / handleMessage]
  H --> F
  B --> I[getPublisher]
  I --> D
  B --> J[close]
  J --> D

Usage

ts
import { NestFactory } from '@nestjs/core';
import { ServerNats } from '@nestjs/microservices';
import { AppModule } from './app.module';

async function bootstrap() {
  const natsServer = new ServerNats({
    servers: ['nats://localhost:4222'],
    queue: 'orders-service',
  });

  const app = await NestFactory.createMicroservice(AppModule, {
    strategy: natsServer,
  });

  await app.listen();

  // Access the underlying NATS client when transport-specific APIs are needed.
  const client = natsServer.unwrap();
  console.log('Connected to NATS:', Boolean(client));
}

bootstrap();

AI Coding Instructions

• Use ServerNats as a custom NestJS microservice transport strategy; let Nest register handlers before calling listen().
• Register message patterns through Nest decorators such as @MessagePattern() and @EventPattern() rather than manually subscribing through the underlying client.
• Keep NATS connection settings, queue groups, and serializer/deserializer options in the transport configuration passed to the constructor.
• Call close() during application shutdown when managing the server lifecycle manually.
• Use unwrap() only for NATS-client-specific functionality; avoid bypassing Nest message handling for normal request and event processing.

Relationships

• IMPORTS → isObject
• IMPORTS → isUndefined

Used by

1 reference from 1 file. Each is a place in this repository where the symbol is actually used — go read one rather than trusting an example.

Imported by (1)

• NatsSubscriber — sample/03-microservices/src/common/strategies/nats.strategy.ts:3