Architecting Silverlight Applications with MVVM

2. Architecting Silverlight Applications with MVVM Shawn Wildermuth President AgiliTrain Session Code: WIA301

3. The Problem

4. The Problem (2) • Tight Coupling • Adds Complexity • Simple Changes Cascade • Difficult to Test • Difficult to Develop Large Applications

5. Separation of Concerns • Loose Coupling • Layers are Individually Responsible • Established Patterns • Lessens the Need to Reinvent Architecture

6. Patterns • Model-View-Controller • Model-View-Presenter • Model-View-ViewModel

7. Patterns (2) • XAML is Declarative • Allows for Code-less Views • Older Patterns Don’t Fit

8. Model-View-ViewModel Model View-Model View

9. Model-View-ViewModel (2) Silverlight XAML View C#/VB ViewModel Model Internet Server C#/VB Services

10. Building the MVVM • Planning on MVVM • Build in Tiers • Plan for Testing

11. Building the MVVM (2) • The Model • Expose Data as Collections • Expose Methods for Different Data Shaping • More than one ViewModel May Use a single Model • Build Interface Providing Data • Allows Mocking of the Database if necessary • Eliminate Tight Coupling of Services with Model

12. demo The Model

13. Building the MVVM (4) • The ViewModel • Expose API that the View Needs • Use the Model to Provide the Data

14. demo The ViewModel

15. Building the MVVM (6) • The View • Declarative UI • Use as Much XAML as Possible • Don’t Write Code to Rebind Data • Perfect View is Code-less • In Silverlight 3 Behaviors and Element Binding Help

16. demo The View

17. Evolving Pattern • MVVM is Still Growing • Some Frameworks Support it (e.g. Prism) • Philosophy of Specifics is not settled • View-Centric • ViewModel-Centric • Marriage/Mediator • No Completely Right/Wrong Way to Implement It • Patterns Only Good If They Help

18. Frameworks • I Hand-Coded MVVM • Frameworks Help • Laurent Bugnion’s Light MVVM • http://www.galasoft.ch/mvvm/getstarted/ • Nikhilk Kothari’s FX Framework • http://projects.nikhilk.net/SilverlightFX • Michael Sync’s Silverlight MVVM Toolkit • http://silverlightmvvm.codeplex.com/

19. question & answer

20. Resources • www.microsoft.com/teched Sessions On-Demand & Community • www.microsoft.com/learning • Microsoft Certification & Training Resources • http://microsoft.com/technet • Resources for IT Professionals • http://microsoft.com/msdn Resources for Developers

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