MVC, MVP and MVVM

MVC

All input coming from user interaction, such mouse click. are directed to the Controller first. The Controller then kick off some functionality. A single Controller may render many different Views based on the operation being executed.  Also view doesn’t have any knowledge of or reference to the Controller. Controller interact with the Model and pass the model to the View. So there is a knowledge between the View and Model  being passed on to it.

MVP

MVP pattern looks very similar to MVC pattern, but has some key distinctions. In MVP, the input is directed to the View not the Presenter. For each View, there is a dedicated Presenter to render that View. The View hold the reference to the Presenter. The Presenter is also reacting to events being triggered from the View, so its aware of the View its associated with it. The Presenter updates the View with the data from the Model and vice versa. But he View is not aware of the Model.

MVVM

Like MVP pattern, the input is directed to  the View. View hold a reference to the ViewModel. But ViewModel is not aware of the View. So it is possible to have one ViewModel to support many Views. You can have a WPF view, Windows Phone or Silverlight View use the same ViewModel. Also the Model is decoupled from the View.  ViewModel interact with the Model and feed the View with the data.

Conclusion

This is just a scratch on the surface. This help you at a higher level, to understand the main differences between these 3 pattern. There are lot resources out which explain how to program using these patterns.  I will post some more details on these patterns in my future posts.