CODEWITHSUNDEEP
node.jseventsrabbitmqmicroservicesnestjs
user2534584
user2534584

Reputation: 533

NestJS - Combine HTTP with RabbitMQ in microservices

I have a few microservices, which are exposed through an API-Gateway. The gateway takes care of handling authentication and routing into the system. The services behind the gateway are mostly simple CRUD-Services. Each service exposes its own API and they communicate synchronously via HTTP. All of these services, including the API-Gateway, are "default" NestJS applications.

Let's stick with the Cats example. Whenever the Cat-Service updates or creates a new Cat, I want an CatCreatedEvent or CatUpdatedEvent to be emmited. The event should be pushed into some message broker like RabbitMQ and another service should listen to this event and process the event asynchronously.

I am not sure how to achive this, in terms of how to "inject" RabbitMQ the right way and I am wondering if this approach makes sense in generel. I have seen the CQRS Module for NestJS, but i think CQRS is a bit too much for this domain. Especially because there is no benefit in this domain to split read- and write-models. Maybe I am totally on the wrong track, so I hope you can give me some advises.

Upvotes: 11

Views: 16722

Answers (2)

Kim Kern
Kim Kern

Reputation: 60457

RabbitMQ is supported in nestjs as a microservice. If you want your application to support both http requests and a message broker, you can create a hybrid application.

// Create your regular nest application.
const app = await NestFactory.create(ApplicationModule);

// Then combine it with a RabbitMQ microservice
const microservice = app.connectMicroservice({
  transport: Transport.RMQ,
  options: {
    urls: [`amqp://localhost:5672`],
    queue: 'my_queue',
    queueOptions: { durable: false },
  },
});

await app.startAllMicroservices();
await app.listen(3001);

Upvotes: 32

Tanjin Alam
Tanjin Alam

Reputation: 2496

Note startAllMicroservicesAsync is depricated****

import { Transport, MicroserviceOptions } from '@nestjs/microservices';
        const app = await NestFactory.create(AppModule);
              app.connectMicroservice<MicroserviceOptions>({
                transport: Transport.TCP,
                options: { retryAttempts: 5, retryDelay: 3000 },
              });
            
              await app.startAllMicroservices();
              await app.listen(3001);
              console.log(`Application is running on: ${await app.getUrl()}`);

Upvotes: 3

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