The ASP.NET MVC Preview 3 release provides a new Model-View-Controller (MVC) framework on top of the existing ASP.NET 3.5 runtime. This means that developers can take advantage of the MVC design patterns to create their Web Applications which includes the ability to achieve and maintain a clear separation of concerns (the UI or view from the business and application logic and backend data), as well as facilitate test driven development (TDD). The ASP.NET MVC framework defines a specific pattern to the Web Application folder structure and provides a controller base-class to handle and process requests for “actions”. Developers can take advantage of the specific Visual Studio 2008 MVC templates within this release to create their Web applications, which includes the ability to select a specific Unit Test structure to accompany their Web Application development.

The MVC framework is fully extensible at all points, allowing developers to create sophisticated structures that meet their needs, including for example Dependency Injection (DI) techniques, new view rendering engines or specialized controllers.

As the ASP.NET MVC framework is built on ASP.NET 3.5, developers can take advantage of many existing ASP.NET 3.5 features, such as localization, authorization, Profile etc.

• Scott Guthrie: ASP.NET MVC Preview 3 Release