Model View ViewModel

The Model View ViewModel (MVVM) is an architectural pattern used in software engineering that originated from Microsoft as a specialization of the Presentation Model design pattern introduced by Martin Fowler. Largely based on the model–view–controller pattern (MVC), MVVM is a specific implementation targeted at UI development platforms which support the event-driven programming in Windows Presentation Foundation (WPF) and Silverlight on the .NET platforms using XAML and .NET languages. Technically different, but similar, Presentation Model design patterns are available in HTML5 through AngularJS, KnockoutJS, Ext JS, Vue.js, and for Java the ZK framework (Model-View-Binder). MVVM facilitates a clear separation of the development of the graphical user interface (either as markup language or GUI code) from the development of the business logic or back end logic known as the model (also known as the data model to distinguish it from the view model). The view model of MVVM is a value converter meaning that the view model is responsible for exposing the data objects from the model in such a way that those objects are easily managed and consumed. In this respect, the view model is more model than view, and handles most if not all of the view’s display logic (though the demarcation between what functions are handled by which layer is a subject of ongoing discussion and exploration). The view model may also implement a mediator pattern organising access to the backend logic around the set of use cases supported by the view. This video is targeted to blind users. Attribution: Article text available under CC-BY-SA Creative Commons image source in video