MirasysSolutions
nestjs-jetstream-transporter
A custom transporter for integrating NATS with NestJS microservices. It provides an implementation for receiving and sending messages using the NATS messaging system.
Installation
npm i @mirasys/nestjs-jetstream-transporterNestJS NATS Config
In app.module.ts, import the NatsService from the lib, provide NAST connection options and NAST consumer options, then put these into the App providers.
@Module({
imports: [],
controllers: [AppController],
providers: [
{
provide: 'NATS_CONNECTION_OPTIONS',
useValue: <ConnectionOptions>
servers: ['nats://eventbus: 4222'],
name: `${process.env.npm_package_name}`,
noEcho: true,
debug: false,
},
{
provide: 'NATS_CONSUMER_OPTIONS',
useValue: <ConsumerConfig>{
deliver_group: process.env.npm_package_name,
max_ack_pending: 100,
ack_policy: AckPolicy. Explicit,
}б
},
AppService,
NatsService,
]
})
export class AppModule {}In main.ts, connect the microservice with NATS strategy, like so:
import { NestFactory } from '@nestjs/core';
import { AppModule } from './app.module';
import {
FastifyAdapter,
NestFastifyApplication,
} from '@nestjs/platform-fastify';
import { NatsService } from './nats-streaming';
async function bootstrap() {
const app = await NestFactory.create<NestFastifyApplication>(
AppModule,
new FastifyAdapter(),
);
app.connectMicroservice({
strategy: app.get (NatsService).strategy,
});
await app.startAllMicroservices();
await app.listen (3000, ¹0.0.0.0¹);
}
bootstrap();
NestJS Producer example
To publish events, we inject the NatsService and call the publish method with the event topic and event data:
constructor(
private readonly natsService: NatsService,
) {}
async someFunction() {
const data = {
name: 'Mirasys Oy',
address: 'Vaisalantie 2, 02130 Espoo, Finland',
};
await this.orgService.save(data);
this.natsService.publish('organization.added', JSON.stringify(data));
}
NestJS Consumer example
To subscribe to events, we use the @EventPattern decorator, note that we need to call the ack() method when finish processing the event.
import { Ctx, EventPattern, Payload } from '@nestjs/microservices';
import { JsMsg } from 'nats';
import { NatsService } from './nats-streaming';
@EventPattern('organization.fetched')
handleOrgFetched(@Payload() data: any, @Ctx() context: JsMsg) {
console.log('data:', data);
context.ack();
}