Durchgehendes Praxisprojekt: Order & Billing Platform

public final class PlaceOrderUseCase {
    private final OrderRepository orders;       // Pattern: Repository Port
    private final InventoryPort inventory;      // Pattern: Port
    private final TransactionRunner tx;         // Pattern: Unit of Work Boundary
    private final OutboxPort outbox;            // Pattern: Transactional Outbox

    public PlaceOrderUseCase(OrderRepository orders, InventoryPort inventory,
                             TransactionRunner tx, OutboxPort outbox) {
        this.orders = orders;
        this.inventory = inventory;
        this.tx = tx;
        this.outbox = outbox;
    }

    public OrderId handle(PlaceOrderCommand command) {
        return tx.required(() -> {
            inventory.reserve(command.customerId(), command.lines());
            Order order = Order.place(command.customerId(), command.lines()); // Factory Method
            orders.save(order);
            outbox.appendAll(order.pullEvents()); // Outbox: Event wird mit Order atomar gespeichert
            return order.id();
        });
    }
}