This document discusses orthogonal architecture and pragmatic approaches. It covers principles like separation of concerns, single responsibility, open/closed, and dependency injection. It provides examples of applying these principles through presentation patterns with views, presenters, and tests. It also discusses using a message bus, dependency injection containers, aspect-oriented programming, and resources for further reading.

1. Orthogonal ArchitectureA pragmatic approach Sergey Shishkin InterComponentWare AG sergey.shishkin@icw.de http://shishkin.org

2. This talk is supposed to be focused on...

3. This talk is not supposed to discuss in detail...

4. What is architecture?

5. Architecture Open Space 2009 http://picasaweb.google.com/lcorneliussen/ArchitectureNETOpenSpace2009#5347109274901628498

6. The decisions that are hard to change —Martin Fowler, PoEA

7. Reversibility

8. The Last Responsible Moment

9. S.O.L.I.D.

10. Open/Closed Principle

11. Presentation Patterns

12. The View publicclassEditPatientView:UserControl, IEditPatientView { privateEditPatientPresenter presenter; publicEditPatientView() { PatientName = newTextBoxAdapter(patientNameTextBox); } publicIViewElementPatientName { get; set; } privatevoidOnSaveClicked(object sender, EventArgs e) { presenter.SavePatient(); } }

13. The Presenter publicclassEditPatientPresenter : Presenter { publicvoidSavePatient() { if (Validate(view.PatientName.IsRequired( "Name is required"))) { var name = view.PatientName.Text; ... } } ... }

14. The Test publicclassWhen_patient_name_is_missing : InstanceContextSpecification<EditPatientPresenter> { protectedoverridevoid Because() { The<IEditPatientView>().PatientName.Text = ""; } [Observation] publicvoidShould_display_error_message() { The<IEditPatientView>().PatientName.ErrorMessage .ShouldNotBeNull(); } }

15. Dependency Injection Container

16. Constructor Injection I’m not going to call this constructor in my code publicclassEditPatientPresenter { privateIEditPatientView view; privateIMessageBus bus; publicEditPatientPresenter( IEditPatientView view, IMessageBus bus) { this.view = view; this.bus = bus; } }

17. Message Bus / Event Broker

18. Message Bus publicclassEditPatientPresenter { ... publicvoidSavePatient() { var command = newEditPatientCommand { Patient = view.Patient }; bus.Send(command); } }

19. Service Layer publicclassPatientHandler : IHandler<EditPatientCommand> { publicvoid Handle(EditPatientCommand message) { using (vartx = newTransactionScope()) { var patient = repository.Get( message.PatientId); patient.ChangeName(message.PatientName); repository.Save(patient); tx.Complete(); } } }

20. Data Access Layer / O/R Mapper

21. Querying publicstaticclassPatientRepositoryExtensions { publicstaticICollection<Patient> FindByName( thisIRepository<Patient> repository, stringsearchText) { returnrepository.AllEntities .Where(p => p.Name.Contains(searchText)) .ToList(); } } var collection = repository.FindByName(“Smith”);

22. Aspect-Oriented Programming

23. Automated Tests Continuous Integration Refactoring

24. Resources SOLID http://butunclebob.com/ArticleS.UncleBob.PrinciplesOfOod Presentation Patterns: http://www.jeremydmiller.com/ppatterns/ Clean Code Developer http://clean-code-developer.de Books: Michael Feathers, “Working effectively with legacy code” Robert C. Martin, “Clean code” and “Agile principles, patterns and practices in C#” Martin Fowler, “Patterns of enterprise architecture”

25. Q&A Sergey Shishkin sergey.shishkin@icw.de http://shishkin.org