A few weeks ago, Scott Guthrie announced on his blog that the ASP.NET team is working on a new MVC Framework for ASP.NET web sites.

MVC stands for Model View Controller and is a well-known pattern that came out of the SmallTalk world almost 30 years ago. I could confess that it was not a well-known pattern to me when I first heard someone talking about it earlier this year, but I'll skip that declaration and move on.

We often talk about separating data from presentation, but MVC goes one step further - creating three distinct and loosely coupled layers: presentation, data and domain logic. The domain logic does all the hard work - determining what to do in response to user requests and input.

MVC in ASP.NET would mean that rather than designing individual pages depending on the particular function in your website, you let the controller decide which view is required and based on a set of available views, it will generate the appropriate one.

In reading Scott's blog post as well as Jeffrey Palermo's CoDe Magazine article (and chatting with Jeffrey) I realize that there are two other major pieces to this puzzle.

The first is that MVC more easily enables unit testing and the second is that it does away with the complexities of ASP.NET web page postbacks.

I'm noticing that web developers with a deep history of designing sites (going back before ASP.NET) are embracing the latter as the way things ought to be. Someone like me who came from a rich client background and got her real first taste of web development with ASP.NET is going to have a harder time grokking this. But basically, rather than having the page hang around even when you do server side interaction (which causes post-backs and therefore requires a good deal of scrambling to make it seem as though the data never went away), just let it go away and recreate the page from scratch.

Of course, this would be dreadful if we didn't have AJAX, so without the historical perspective these guys have, from where I sit, it seems that AJAX just makes it easier for developers to build rich client web apps (and there's always silverlight) removes the need to have to fake persistence.

MVC is just getting started in ASP.NET, but Scott presented it at the ALT.NET conference recently and has a link to a video of that presentation in his blog. if you plan to be creating websites for a while, you will definitely want to take a look. Don't worry though, this is not a replacement for webforms, but an additional option for developers.

10/26 Update: Adding an additional link to a nice & neat explanation of the MVC pattern, the MVP (model viewer presentation) pattern and the basic differences between them by Todd Snyder of Infragistics.