OrderNotify Bus

This project is a demo to understand event-driven architecture in microservices using Spring Boot, Spring Cloud Stream, and RabbitMQ.

Microservices in this Project

• order-service: Handles order creation and emits events.
• notification-service: Listens for order events and sends notifications.
• discovery-service: Service registry using Eureka.

Running RabbitMQ Locally

You can run RabbitMQ using Docker (with or without Docker Desktop). If you don't want Docker Desktop, you can use Colima as a lightweight Docker runtime for macOS.

Start Colima (if not using Docker Desktop)

brew install colima
colima start

Run RabbitMQ with Docker

docker run -d --hostname rabbitmq --name rabbitmq -p 5672:5672 -p 15672:15672 rabbitmq:3-management

• Management UI: http://localhost:15672 (user: guest, pass: guest)
• AMQP port: 5672

Reliability Notes

• Messages are not lost if your consumer service is down, as long as:
  • The queue is durable
  • Messages are persistent
• DLQ (Dead Letter Queue) is recommended for handling messages that cannot be processed after several attempts, but is not required for temporary consumer downtime.
• Monitor queue size and disk space if your service may be down for an extended period.

Developer Usage

1. Start RabbitMQ as above.
2. Start each microservice (order, notification, discovery) using Maven or your IDE.
3. Place your RabbitMQ connection settings in application.properties:

   spring.rabbitmq.host=localhost
   spring.rabbitmq.port=5672
   spring.rabbitmq.username=guest
   spring.rabbitmq.password=guest

4. Create an order via the order-service API to see event-driven flow.

Useful Commands

• Check what is using a port:

  lsof -i :5672

• View running Docker containers:

  docker ps

License

MIT