This is an example Nest monorepo project with two microservices communicating asynchronously with each other via events over basic Nest's TCP Transporter.
The first microservice (api-service) exposes a GET / endpoint which, when requested, sends an event to the second microservice (worker-service) through that TCP transporter. worker-service then do some fake processing and sends back an event to the first service to notify it that processing is done.
An important thing to note here is that all of this process is asynchronous, so no matter how much time is needed on the worker side, response is immediate on the API side, because we use event-based message style. If we were using request-response message style, initial request would be blocked until the worker side is done with data processing. The drawback is that there is no guarantee that the messages will be successfully delivered. For that, we would need to add some sort of message broker such as RabbitMQ as a replacement transporter.
$ yarnor
$ npm installOpen two terminal windows and start both services.
To run the api-service:
$ yarn startor
$ npm run startAnd to run the worker-service:
$ yarn start:workeror
$ npm run start:workerWhen both services are started and running, go to http://localhost:3000 then take a look at the terminal windows. You should see some output in both of them.
Feel free to open an issue or make a PR if you think this sample can be improved (it definitely can!).
This example was initially inspired by this article.