Creating Applications using the
Model-View-ViewModel Pattern
Matt Casto
mattcasto@gmail.com
http://twitter.com/mattcasto

Developing Software is HARD

Developing Software is HARD

Patterns Help … but its still HARD!

Model – View – ViewModel

Model – View – Controller

Model – View – Controller
• Regarded as the first pattern to
seperate UI, Data & Logic concerns
• Controller handles all logic,
including Mouse & Keyboard events

Model – View – Presenter

Model – View – Presenter
• Variation of MVC
• Tailored for modern UI that handles
Mouse & Keyboard events better
• Presenter depends on View

Presentation Model

Presentation Model
• Published by Martin Fowler in 2004
• View is a rendering of the
Presentation Model

Presentation Model
“Probably the most annoying part of Presentation
Model is the synchronization between Presentation
Model and view. It’s simple code to write, but I always
like to minimize this kind of boring repetitive code.
Ideally some kind of framework could handle this,
which I’m hoping will happen someday with
technologies like .NET’s data binding.”
– Martin Fowler

Model

Model – Your Data

Model – Your Data
• Entities
• Service Proxy
• POCO

Model – Your Data
View

Model – Your Data
View – User Interface

Model – Your Data
View – User Interface
• XAML (WPF)
• XAML w/ Code Behind (Silverlight)

Model – Your Data
View – User Interface
ViewModel

Model – Your Data
View – User Interface
ViewModel – The View’s Model

Model – Your Data
View – User Interface
ViewModel – The View’s Model
• State
• Operations
• Not Dependent on the View

You’re probably already doing
something very close to this

You probably could be doing
something very close to this

Why do I care about MVVM?

Why should you care about MVVM?

Patterns are a set of guidelines
Patterns are not a set of rules

Benefits of MVVM

Benefits of MVVM
• Loose Coupling
• Testable Code
• Maintainable Code

Developers and Designers

DEMO
WPF vs Silverlight

DEMO
Adding Validation

DEMO
Unit Testing

DEMO
Commands

Enterprisey Solutions
• Component Application Guidance
• Caliburn
• Roll Your Own

Sources
• WPF Apps With The Model-View-ViewModel Design Pattern – Josh Smith
http://msdn.microsoft.com/en-us/magazine/dd419663.aspx
• Model-View-ViewModel In Silverlight 2 Apps – Shawn Wildermuth
http://msdn.microsoft.com/en-us/magazine/dd458800.aspx
• ViewModel Pattern in Silverlight using Behaviors – Nikhil Kothari
http://www.nikhilk.net/Silverlight-ViewModel-Pattern.aspx
• Using RoutedCommands with a ViewModel in WPF – Josh Smith
http://www.codeproject.com/KB/WPF/VMCommanding.aspx
• Presentation Model – Martin Fowler
http://martinfowler.com/eaaDev/PresentationModel.html

THANKS!!
Matt Casto
mattcasto@gmail.com
http://twitter.com/mattcasto