Mastering MVVM: Principles and Practices for Effective Application Development

1. MVVMmmmmmmmmmmm Ward Bell VP Technology, IdeaBlade Twitter: @wardbell Blog: http://neverindoubtnet.blogspot.com/

2. Thanks for the slide deck, John Papa

3. Agenda • MVVM: What and Why • Respond to User Actions • Abstraction • Design with Data • Data Services • Testing

4. Bookshelf in Action demo

5. Model View ViewModel

6. Everybody’s doing it!

7. MVVM View Model

8. MVVM • Model • Domain object • Properties • Model Validation View

9. MVVM • View • The screen or page or control • User friendly presentation of information • Themes and Styles • User interactions Model

11. MVVM Model View ViewModel

12. MVVM • ViewModel • Glues the View to the Model • Databound to the View • Properties • Commands • Methods • Contains the Model • Talks to services and load/save the Model Model View

13. MVVM • View • The screen or page or control • User friendly presentation of information • Themes and Styles • User interactions • Bindings • Events • Behaviors ViewModel Model

14. Benefits of MVVM

15. MVVM Presentation logic Binding ViewModel Tell View when data changes Design w/ XAML Model (e.g. PeopleModel/Person) View (e.g. Person Master/Details) XAML Code Not reusable

16. Binding a View to a ViewModel demo ViewModelLocator INotifyPropertyChanged

17. Responding to User Actions

18. Handling User Actions

19. Commands and Behaviors demo

20. Services and Separation

21. + Services MVVM Reusable Services VM V M • ViewModel • Presentation logic • Handle user interaction • Reference Models • Services • Perform operations • Reusable tasks Model View

22. Separating the Services • Services provide related tasks to the caller • BookDataService, SecurityService, BookEditor • ViewModel uses a Service • Passed through the constructor (Dependency Injection) • ViewModel can focus on bindings and logic • Easily refactored and testable • Services implement an interface

23. Adding Value with Services demo BookViewModel talks to services

24. RIA Platforms and MVVM

25. RIA Platforms • Data access and Server communications • Data modeling as Entities (not DTOs) • Binding directly to Entities • INPC and INDEI • You get EntityManager/DomainContext • Your gateway to the server • Change tracking • Abstraction through Services

26. DevForce and MVVM demo Behind the BookDataService

27. + Messaging MVVM VM VM Direct Message? V V M M

28. + Messaging MVVM EventAggregator Pattern VM VM V V M M Subscribe Messaging Service Publish Subscribe Confirmation Dialog

29. Confirmation Dialog Example • Define a message type (ConfirmationDialogMessage) • Send method knows MessengerService • Message defines its own payload • Publish message (BookSaver:SaveSuccessful) • Subscribe to message (MainPage:DialogMessageReceived) • Subscriber acquires MessengerService • Subscriber registers action for message

30. Messaging demo

31. Blendability & Design Time Data

32. Design Time Data What am I looking at? Ah! Are my bindings right? How’s my layout? Isn’t this easier/more productive? Notice I’ve tested my Submit Button Logic

33. Swapping Services • Services won’t run in the Blend and Visual Studio designers • Need design time calls • Service Providers • If DesignTime • Create Design Time Services • Else • Create Regular Services

34. Blendability: Data in the Designer demo Service Provider and Design Time Services Using cached sample data - “Self-initializing Fake”

35. Automated Testing demo

36. Review: Benefits of MVVM

37. Summary • MVVM: What and Why • Respond to User Actions • Abstraction • Design with Data • Data Services • Testing

38. Resources Web: IdeaBlade: www.ideablade.com Bookshelf in DevForce: links.ideablade.com/drc-bookshelf SL Firestarter 2010: links.ideablade.com/firestarter10-mvvm MIX 2010 MVVM: links.ideablade.com/mix10-laurent-mvvm MVVM Light: links.ideablade.com/mvvmlight SL Test Framework: links.ideablade.com/sl-utf Print: Silverlight 4 Unleashed, Laurent Bugnion