Overview

The Notification Service is a supporting service within BookWorm’s microservices architecture, responsible for sending transactional emails to customers at critical points in the order lifecycle. Built using an event-driven approach, this service listens for integration events from other domains and transforms them into appropriate customer communications.

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Receives 3 messages

This service receives messages from other services

Architecture diagram

Technical Implementation

The Notification Service is implemented using modern cloud-native practices:

Email Providers

The service supports multiple email delivery mechanisms through a clean abstraction:

• Development Environment: Uses local SMTP server (MailPit) for testing
• Production Environment: Integrates with SendGrid for reliable email delivery
• Interface Abstraction: Implements ISmtpClient interface for provider flexibility

Message Flow

The Notification Service processes the following commands:

Command	Channel	Purpose
PlaceOrderCommand	notification-place-order	Sends order confirmation emails
CompleteOrderCommand	notification-complete-order	Sends order completion notifications
CancelOrderCommand	notification-cancel-order	Delivers order cancellation notices

Email Templates

Each notification type follows a standardized template structure:

• Order Confirmation: “Your order has been placed successfully.”
• Order Completion: “Your order has been completed successfully.”
• Order Cancellation: “Your order has been cancelled.”

Infrastructure

The Notification Service is deployed on Microsoft Azure, leveraging Azure Service Bus for message consumption and Azure Monitor for observability.

For Development environment, the service uses MailPit for email delivery.

For Production environment, the service uses SendGrid for email delivery.