The document introduces the Model-View-ViewModel (MVVM) pattern. It describes MVVM as replacing the controller with a view model to facilitate data binding between the view and model. The key components in MVVM are the model, which represents the business domain and data access logic; the view, which displays data and collects user input; and the view model, which acts as an intermediary between the view and model by aggregating data and notifying the view of changes. The document provides examples of how MVVM is implemented in Silverlight applications using the MVVM Light Toolkit to define commands and handle events and messaging between the view and view model.

1. Introduction to MVVM In SilverlightHoneyson Joseph D http:/facebook.com/honeydev1http:/facebook/honeydev

2. What is MVVM ?? MVVM is nothing but a Pattern.

3. Also known as Presentational Model.

4. Model-View-ViewModelpattern is similar to MVC2http:/facebook/honeydev

5. Let’s see some variations of similar patternsMVC PatternModel View Controller is probably the oldest pattern.

6. Still using widely, especially with ASP.NET MVC.3http:/facebook/honeydev

7. Passive View PatternView is completely Passive.

8. The controller has lot of responsibilities.

9. Testing a View is very difficult and time consuming.4http:/facebook/honeydev

10. Presentation Model Pattern(MVVM) Controlleris replaced with ViewModel.

11. Viewis more active and pushing information to the Model.

12. The interactions is done via Data Binding.5http:/facebook/honeydev

13. 6http:/facebook/honeydev

14. ModelModel represents the business domain which includes themodel classes used (Customer, Order, etc.), data accesscode and business rules.7http:/facebook/honeydev

15. View Viewin MVVM represents the screens that we build.Includes : 1.XAML files 2.code-beside files Responsibilities : 1.displaying data 2.collecting data from end users View isn't responsible for retrieving data, performing any business rules or validating data8http:/facebook/honeydev