Message Bus - RabbitMQ Event System

This is a reusable RabbitMQ message bus for microservices communication.

Features

• ✅ Automatic RabbitMQ connection with retry logic
• ✅ Event publishing to exchanges and queues
• ✅ Event subscription with durable queues
• ✅ Automatic acknowledgment handling
• ✅ Error handling and message requeuing
• ✅ Service-specific queue naming

Configuration

Environment Variables

RABBITMQ_URL=amqp://guest:guest@rabbitmq:5672

Event Configuration

Events are configured in event.config.js:

"application.approved": {
  type: "exchange",        // "exchange" or "queue"
  name: "application.events", // exchange/queue name
  subscribers: ["Subscription-Service"]
}

Usage

Publishing Events

const { publishEvent } = require("message-bus");

await publishEvent("application.approved", {
  personalDetailsId: "123",
  userId: "456",
  subscriptionDetails: {...},
  approvalDetails: {...}
});

Subscribing to Events

const { subscribeToEvent } = require("message-bus");

await subscribeToEvent(
  "application.approved",
  async (data) => {
    // Handle the event data
    console.log("Application approved:", data);
  },
  "Subscription-Service"
);

Testing

Test Connection

node test-connection.js

Test with Docker

1. Start the services:

./run-docker.sh

2. Check RabbitMQ management console:

   • URL: http://localhost:15672
   • Username: guest
   • Password: guest

3. Monitor logs for connection status:

docker logs message-bus

Architecture

Portal Service → RabbitMQ Exchange → Subscription Service
     ↓              ↓                    ↓
  Publishes    Routes Events         Consumes Events
  Events       to Queues            and Creates
                                    Subscriptions

Troubleshooting

Connection Issues

1. Ensure RabbitMQ container is running:

docker ps | grep rabbitmq

2. Check RabbitMQ logs:

docker logs rabbitmq

3. Verify network connectivity:

docker network ls
docker network inspect mainnetwork

Event Not Received

1. Check if event is published:

docker logs portal-service | grep "Published"

2. Check if event is received:

docker logs subscription-service | grep "Processing"

3. Verify exchange and queue exist in RabbitMQ management console

Supported Events

• application.approved - Application approval events
• application.rejected - Application rejection events
• user.microsoftAuthenticated - User authentication events
• lookuptype.* - Lookup type CRUD events
• personalDetails.* - Personal details CRUD events
• professionalDetails.* - Professional details CRUD events
• subscriptionDetails.* - Subscription details CRUD events
• userInformation.* - User information events