Designing System Architecture Patterns

// Port (defined in core)
public interface OrderRepository {
    Optional<Order> findById(OrderId id);
    void save(Order order);
}

// Adapter (infrastructure)
@Repository
class JpaOrderRepository implements OrderRepository {
    private final OrderJpaRepo jpa;
    public Optional<Order> findById(OrderId id) { return jpa.findById(id.value()).map(this::toDomain); }
    public void save(Order order) { jpa.save(toEntity(order)); }
}

class Account {
    private long balance;
    private final List<Event> uncommitted = new ArrayList<>();

    void deposit(long amount) {
        apply(new MoneyDeposited(amount));
    }
    void apply(Event e) {
        if (e instanceof MoneyDeposited d) balance += d.amount();
        uncommitted.add(e);
    }
    static Account rehydrate(List<Event> history) {
        var a = new Account();
        history.forEach(a::apply);
        a.uncommitted.clear();
        return a;
    }
}