# Build and start all servicesdocker-compose up --build# Run in detached modedocker-compose up -d# View logsdocker-compose logs -f# Stop all servicesdocker-compose down
The core/ package contains pure business logic with no framework dependencies.
No Spring annotations in domain code
No JPA entities in the domain
Domain defines interfaces (ports), infrastructure implements them
This makes the domain easy to test and completely portable.
Dependency Rule
Dependencies flow inward:
Infrastructure → Application → Domain
Domain depends on nothing
Application depends on domain
Infrastructure depends on both
Ports and Adapters
Ports: Interfaces defined in the domain
Adapters: Implementations in infrastructure
Example:
// Port (in core/ports/out/)public interface AiGeneratorPort { String generateResponse(String input);}// Adapter (in infrastructure/adapters/out/ai/)@Componentpublic class OpenRouterAdapter implements AiGeneratorPort { // Implementation using OpenRouter API}
Add entities and value objects in core/domain/model/
public class Feature { private final String id; private final String name; // Domain logic here}
2
Create ports
Define input port (use case interface) in core/ports/in/:
public interface CreateFeaturePort { Feature create(CreateFeatureCommand command);}
Define output port (dependency interface) in core/ports/out/:
public interface FeatureRepositoryPort { Feature save(Feature feature); Optional<Feature> findById(String id);}
3
Implement use case
Create use case in application/usecases/:
public class CreateFeatureUseCase implements CreateFeaturePort { private final FeatureRepositoryPort repository; @Override public Feature create(CreateFeatureCommand command) { // Business logic return repository.save(feature); }}
4
Implement adapters
Input adapter (REST controller):
@RestController@RequestMapping("/features")public class FeatureController { private final CreateFeaturePort createFeaturePort; @PostMapping public ResponseEntity<FeatureDto> create(@RequestBody CreateFeatureRequest request) { Feature feature = createFeaturePort.create(new CreateFeatureCommand(request.name())); return ResponseEntity.ok(toDto(feature)); }}
Output adapter (repository):
@Componentpublic class FeatureRepositoryAdapter implements FeatureRepositoryPort { private final FeatureJpaRepository jpaRepository; @Override public Feature save(Feature feature) { FeatureEntity entity = toEntity(feature); FeatureEntity saved = jpaRepository.save(entity); return toDomain(saved); }}
5
Configure beans
Wire everything in BeanConfiguration.java:
@Beanpublic CreateFeaturePort createFeatureUseCase(FeatureRepositoryPort repository) { return new CreateFeatureUseCase(repository);}
6
Write tests
Unit test for use case:
class CreateFeatureUseCaseTest { @Test void shouldCreateFeature() { // Arrange FeatureRepositoryPort repository = mock(FeatureRepositoryPort.class); CreateFeatureUseCase useCase = new CreateFeatureUseCase(repository); // Act Feature result = useCase.create(new CreateFeatureCommand("New Feature")); // Assert verify(repository).save(any(Feature.class)); }}
# Clean buildmvn clean install -DskipTests# Run with specific profilemvn spring-boot:run -Dspring-boot.run.profiles=dev# Generate JAR without running testsmvn package -DskipTests# Check for dependency updatesmvn versions:display-dependency-updates# Format code (if configured)mvn spotless:apply# View dependency treemvn dependency:tree
