Spring Boot DDD E-Commerce Order Management System

This project is a comprehensive Spring Boot application that demonstrates Domain-Driven Design (DDD) principles through a real-world e-commerce order management system. It follows clean architecture with a strong separation of concerns and rich domain modeling.

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Project Overview

The system manages customers, products, and orders, ensuring that all business rules are enforced within the domain layer. Each bounded context is clearly structured, making the application scalable, maintainable, and easy to extend.

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Architecture (DDD-Based)

The application is structured into the following layers:

Domain Layer

• Rich domain models:
  • Customer
  • Product
  • Order
• Business rules encapsulated inside domain objects
• No dependency on frameworks

Application Layer

• Use cases (application services)
• DTOs for data transfer
• Transaction orchestration

Infrastructure Layer

• JPA entities
• Spring Data JPA repositories
• Database configuration

Web Layer

• REST controllers
• Request/response handling
• Global exception handling

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Core Domain-Driven Design Concepts

• Aggregates
  • Order, Customer, and Product as aggregate roots
• Value Objects
  • Money
  • Email
  • CustomerId
  • Immutable and self-validating
• Domain Events
  • OrderCreatedEvent for decoupled communication
• Repositories
  • Clean abstraction over data access
• Ubiquitous Language
  • Business-focused terminology used consistently across the codebase

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Business Logic

• Customer management with email validation
• Product inventory tracking
• Order creation with stock validation
• Domain event publishing
• Transaction management
• Comprehensive error handling

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Tech Stack

• Java
• Spring Boot 4.0.0
• Spring Data JPA
• H2 Database (In-Memory)
• JUnit 5
• Maven

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API Features

• Customer CRUD operations
• Product management
• Order creation and retrieval
• Centralized error handling
• RESTful API design

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Testing

• Comprehensive unit tests
• Domain logic tested independently
• Sample data included for quick testing

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Running the Application

Start the application:

mvn spring-boot:run

Access the H2 Console

http://localhost:8080/h2-console

Database credentials can be found in the application configuration.

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Key Takeaways

• Proper implementation of Domain-Driven Design
• Clean architecture with strict separation of concerns
• Business logic fully encapsulated in the domain layer
• Framework-independent core domain
• Solid foundation for enterprise-level applications

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Use Case

This project is suitable for:

• Learning Domain-Driven Design with Spring Boot
• Backend architecture reference
• Clean architecture demonstrations
• Interview and portfolio projects