CredApp Notification Service

The notification microservice delivers asynchronous notifications for the CredApp platform. It is designed for horizontal scalability and communicates via RabbitMQ to decouple notification delivery from the main workflow.

Features

• FastAPI-powered HTTP API for enqueuing notification events.
• Asynchronous message publishing and consumption using RabbitMQ (aio-pika).
• Pluggable dispatcher that can be extended with e-mail, SMS, push, and in-app channels.
• Configurable via environment variables using pydantic-settings.
• Lifespan hooks ensure graceful startup, shutdown, and resource cleanup.
• Built-in rule engine that maps core CredApp events across issuer, learner, and employer roles.

Getting Started

1. Install dependencies

   cd notification_service
   ..\backend1\venv\Scripts\python -m pip install -r requirements.txt

2. Export environment variables (optional)

   Create an .env file in notification_service to override defaults.

   APP_NAME=CredApp Notification Service
   RABBITMQ_URL=amqp://guest:guest@localhost:5672/
   RABBITMQ_EXCHANGE=notifications.exchange
   RABBITMQ_QUEUE=notifications.queue

3. Run RabbitMQ

   Ensure RabbitMQ is running locally or reachable from the configured URL. Example with Docker:

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

4. Start the service

   ..\backend1\venv\Scripts\uvicorn app.main:app --reload --host 0.0.0.0 --port 8500

API

• POST /api/v1/notifications – enqueue a notification event.

Example request body:

{
  "event_type": "credential.issued",
  "actor_role": "issuer",
  "recipients": ["learner@example.com"],
  "subject": "Your credential is ready",
  "body": "Congratulations! Your credential has been issued.",
  "metadata": {
    "credential_id": "abc123"
  }
}

Built-in event defaults

The rule engine enriches requests with default channels and audiences when you omit them:

Event	Actor role	Default recipients	Default channels	Use case
credential.issued	issuer	learner	email, in_app	Notify learner when issuer issues a document
credential.updated	issuer	learner	email, in_app	Credential metadata updated
credential.revoked	issuer	learner	email, in_app	Credential revoked
profile.viewed	employer	learner	in_app	Employer viewed learner profile
employer.requested_verification	employer	issuer	email, in_app	Employer sought verification from issuer

Override channels by passing a channels array, and override audiences via recipient_roles. The service always requires explicit recipients (email addresses, phone numbers, or internal IDs) so downstream transports know where to deliver.

Scaling

• Deploy multiple instances of the service to scale consumers horizontally; RabbitMQ handles load balancing across consumers.
• Adjust RABBITMQ_PREFETCH_COUNT and WORKER_CONCURRENCY to tune throughput.
• Extend NotificationDispatcher to integrate with real delivery providers (e.g. AWS SES, Twilio, Firebase Cloud Messaging).

Testing

• You can publish messages directly to RabbitMQ using the provided API or management UI to validate end-to-end flows.
• Add unit tests around the dispatcher as new delivery channels are implemented.