The document discusses the Model-View-ViewModel (MVVM) pattern, which separates an application into three main components: the model, the view, and the view model. It explains that MVVM is best suited for WPF, Silverlight, and Windows Phone applications because these platforms internally use MVVM. The document also describes related patterns like MVC and Presentation Model, how MVVM enables separation of design and runtime code for "blendability", and how to bridge the view and view model using data binding and commands. It debunks common myths about MVVM and recommends the MVVM Light Toolkit for simplifying MVVM applications.

1. /* Life runs on code */

2. UNDERSTANDING
THE MODEL-VIEW-
VIEWMODEL
PATTERN
Kamalakannan Annamalai
Senior Software Engineer
Ilink-Systems
http://kamalakannana.wordpress.com

3. WHAT IS MVVM?
• A weird acronym
– Model – View – ViewModel
• Woven into WPF/SL/WP
• Some confusion:
– MVVM is really just the pattern
– The rest are helpers, practices, etc.
• Why does MVVM pattern is best for
WPF/SL/WP?
-WPF/SL/WP Controls are developed using
MVVM internally.

4. THE MVC PATTERN
Model View
Controller

5. THE PASSIVE VIEW PATTERN
Model View
Controller

6. THE PRESENTATION MODEL PATTERN
Model View
Presentation
Model
(ViewModel)
DataBinding

7. BLENDABILITY
• Testability, Maintainability, Blendability
• “The ability to be edited in Blend”
–(and Visual Studio designer…)
• Differentiate code in design and runtime
• Create design time data
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8. BRIDGING THE GAP
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View
ViewModel
DataBinding Commands Messages
Model

9. BRIDGING THE GAP
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View
ViewModel
View
ViewModel
View
ViewModel

10. DEMO
© 2010 IdentityMine Inc. All Rights Reserved. 10Page:
Hello MVVM
(and Hi Blend)

11. COMMANDS
• “Point of entry” for a method
• Can be data bound
• ICommand interface
–Execute method
–CanExecute method
–CanExecuteChanged event
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12. FLAWS OF MVVM
•
–
–
•
•
•

13. DEBUNK THE MYTHS
• “No code in the code behind”
– “If you put code in the View's code-behind, the
MVVM police will take your family away”
– “No need for converters”
• “MVVM is suitable for big projects”
• “MVVM costs performance”
• “MVVM is complex / makes my head hurt”
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14. DEBUNK THE MYTHS
• “I don’t need separation because I don’t
have a designer”
• “You cannot use MVVM with other
patterns”
• “MVVM will make you rich and attractive”
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15. MVVM LIGHT TOOLKIT
• “Breaking the monotony”
• http://www.galasoft.ch/mvvm/getstarted
• http://mvvmlight.codeplex.com
• Keep it small
• Keep it simple
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16. MVVM LIGHT TOOLS
• Project templates (VS + Blend)
• Item templates (VS + Blend)
• Code snippets
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17. THANKS!