ModelViewViewModel

ModelViewViewModel is not the standard name for a well-known architectural pattern. The canonical term is Model-View-ViewModel (MVVM). The concatenated form may appear as a nonstandard variant or a reader’s shorthand emphasizing the three layers, but MVVM is the widely accepted terminology.

Overview and structure

MVVM is an architectural pattern used in user interface design to separate data, presentation, and UI logic. It divides responsibilities into three components: the Model, which represents domain data and business rules; the View, which is the user interface; and the ViewModel, an abstraction of the View that exposes data and actions for the View to bind to. The View binds to the ViewModel's properties and commands, allowing automatic UI updates through data binding.

Responsibilities and behavior

The ViewModel mediates between the View and the Model. It exposes UI state as properties, implements commands for user actions, and notifies the View of changes (often via INotifyPropertyChanged). It should not hold a reference to the View, which enables unit testing of presentation logic without a UI. The Model remains independent of the View and ViewModel, encapsulating business data and rules.

Usage and variants

MVVM is widely used in UI frameworks with strong data-binding support, especially in the Microsoft ecosystem (WPF, Silverlight, UWP, Xamarin.Forms, MAUI). Variants and tooling include MVVM Light, Prism, and other libraries that provide base classes and services to simplify binding, navigation, and testing. Some projects blend MVVM with other patterns (MVP, MVC) depending on context and complexity.

Benefits and limitations

MVVM improves testability, maintainability, and separation of concerns, and supports design-time data. It can introduce boilerplate and architectural complexity, and may be overkill for simple interfaces. Successful use depends on appropriate binding strategies and a clear distinction between View, ViewModel, and Model.