Skip to content

README.md

Latest commit

 

History

History
97 lines (72 loc) · 3.05 KB

README.md

File metadata and controls

97 lines (72 loc) · 3.05 KB

Order Subscription System

Java Spring Boot PostgreSQL JUnit

Spring Boot project implementing an order and subscription lifecycle.

The main goal of this project is to demonstrate a clean, modular architecture inspired by Domain-Driven Design (DDD). The codebase focuses on keeping business logic inside the domain layer while separating application orchestration and infrastructure concerns.

Architecture

The project follows a layered approach similar to Clean Architecture / Hexagonal Architecture.

  • domain – core business logic (aggregates, value objects, domain events)
  • application – use cases and orchestration
  • infrastructure – persistence and framework-specific implementations
  • bootstrap – Spring Boot configuration and delivery layer (REST, scheduling)

The domain layer has no framework dependencies, making it easy to test and reason about.

Domain Model

The domain models the lifecycle of orders and subscriptions.

Key concepts:

  • Order
  • Subscription
  • Domain events describing state transitions

Subscriptions are associated with orders and follow a simple lifecycle:

  1. Start
  2. Cancel
  3. Expire

State transitions are validated inside aggregates to ensure that business rules are always enforced.

Business Rules

The system enforces several rules inside the domain model:

  • A subscription can only start for a paid order
  • An order can only have one active subscription
  • A subscription can be cancelled
  • Subscriptions automatically expire after a defined period
  • Every state change emits a domain event

Expiration is handled externally by a scheduled job which checks subscriptions that passed their expiration date.

Technology Stack

  • Java 17+
  • Spring Boot
  • Spring Data JPA
  • PostgreSQL
  • Flyway (database migrations)
  • Gradle (Kotlin DSL)

Project Structure

order-domain
  Aggregates, value objects, domain events, business rules

order-application
  Use cases, orchestration, repository ports, policies

order-infrastructure
  JPA entities, repository implementations, mappers

order-bootstrap
  Spring Boot configuration, REST controllers, schedulers

Example Use Cases

The application supports several typical operations:

  • Start a subscription for a paid order
  • Prevent duplicate subscriptions for the same order
  • Cancel an active subscription
  • Automatically expire subscriptions after the configured time
  • Publish domain events on state transitions

Running the Application

  1. Start PostgreSQL

  2. Configure database connection in application.yml

  3. Run the application:

    ./gradlew bootRun

Author

Dominik Suliga (dominiks8318@gmail.com)