Kotlin DDD Sample is a open-source project meant to be used as a start point, or an inspiration, for those who want to build Domain Driven Design applications in Kotlin. The domain model was inspired by this repo where we built a sample project using Rails.
NOTE: This is NOT intended to be a definitive solution or a production ready project
- Kotlin
- Spring
- Axon Framework
- CommandGateway (Command Handlers)
- EventBus (Event Handlers)
- Gradle
- Web: Spring controllers and actions
- Application: Orchestrates the jobs in the domain needed to be done to accomplish a certain "use case"
- Domain: Where the business rules resides
- Infrastructure: Technologies concerns resides here (database access, sending emails, calling external APIs)
CQRS splits your application (and even the database in some cases) into two different paths: Commands and Queries.
Every operation that can trigger an side effect on the server must pass through the CQRS "command side". I like to put the Handlers (commands handlers and events handlers) inside the application layer because their goals are almost the same: orchestrate domain operations (also usually using infrastructure services).
Pretty straight forward, the controller receives the request, calls the related query repo and returns a DTO (defined on infrastructure layer itself).
This project is based on a didactic domain that basically consists in maintaining an Order (adding and removing items in it). The operations supported by the application are:
- Create an order
- Add products ta a given order
- Change product quantity
- Remove product
- Pay the order
- Shipping: ships product and notify user
Linux/MacOS:
./gradlew build
Windows:
gradlew.bat build
./gradlew test
- Implement Unit Tests examples (Domain layer)
- Implement Integrated Tests examples (Web layer)
- Include docker container with JDK and gradle configured
- Configure Swagger and Swagger UI
- Include a Event Sourced bounded context or Aggregate
- Domain Notifications instead of raising exceptions
- Implement concrete repositories with JPA (the current implementations just returns fake instances)