ddd-cola

com.example.app/
├── adapter/
│   ├── controller/        # HTTP/RPC/message inbound handlers
│   └── scheduler/         # Scheduled tasks
├── app/
│   ├── executor/          # Use case executors (command handlers)
│   └── service/           # Application services (orchestration, transactions)
├── domain/
│   ├── model/             # Entities, Value Objects, Aggregates
│   │   ├── entity/
│   │   └── valueobject/
│   ├── service/           # Domain services
│   └── gateway/           # Repository and external service interfaces (ports)
└── infrastructure/
    ├── persistence/       # Repository implementations (JPA, MyBatis)
    ├── external/          # External API clients
    └── config/            # Spring configuration and bean wiring

Adapter → Application → Domain ← Infrastructure

// Domain gateway (port)
public interface OrderGateway {
    void save(Order order);
    Optional<Order> findById(String id);
}

// Application executor
@Component
public class CreateOrderExecutor {
    private final OrderGateway orderGateway;

    public CreateOrderExecutor(OrderGateway orderGateway) {
        this.orderGateway = orderGateway;
    }

    @Transactional
    public OrderDto execute(CreateOrderCmd cmd) {
        Order order = Order.create(cmd.getItems(), cmd.getCustomerId());
        orderGateway.save(order);
        return OrderDto.from(order);
    }
}

// Infrastructure implementation
@Repository
public class OrderGatewayImpl implements OrderGateway {
    private final OrderMapper orderMapper;

    @Override
    public void save(Order order) {
        orderMapper.insert(OrderDO.fromDomain(order));
    }
}