Inaugural DevReady event on MVVM

There has been a tremendous amount of hype recently around the MVVM (Model-View- Viewmodel)pattern. Miguel Castro and DevExpress put together a developer day that shows the hype is backed by substance. There was a sold out crowd this past Saturday to see this event at the Microsoft office in Malvern PA. There was a convivial atmosphere created by the three
hispanic presenters: Miguel, Dani Diaz the Microsoft developer evangelist, and Seth Juarez, a DevExpress developer evangelist. The backgrounds of the three speakers, respectively Cuba, Dominican Republic, and Mexico family backgrounds, provided an ongoing source of levity and continuity. The back and forth between the speakers, both light-hearted and technical, helped make the event cohere into a single focused event, not a variety of individual topics like a code camp.

The MVVM pattern was first articulated by Martin Fowler, see http://martinfowler.com/eaaDev/PresentationModel.html. Martin named this the Presentation Model pattern. The MVVM pattern, despite being a really awkward palindrome, is a valuable pattern that has emerged in the rich client area. Web applications, with the need for routing preeminent, tend to emphasize the MVC pattern. Many developers are familiar with what a model and view are by this team. A Model represents the business logic of an application and a View represent a visual interface to an area of the application. The role of the ViewModel is to represent a logical representation of the visual interface.

The core of the event was Miguel’s three sessions on Xaml and MVVM. His Xaml talk really was an overview of WPF development. Attending this talk is a must for developers new to WPF, Silverlight, and WP7. It will be given again at Philly Code Camp on April 9, so check it out there! I can’t quantify just how much time it would have saved me in learning WPF. He talked a lot about layout,which is much different than in Windows Forms or other rich client development. I initially misconstrued the Grid as something like a DataGrid, when it is really intended purely for layout. As Miguel pointed out, the Grid is much like a table in HTML. Miguel drove the point that WPF layout is really driven a lot by how HTML and CSS combine to represent web markup. Miguel showed how using a drag and drop approach adds a lot of bad markup to the XAML. He did point out that the DevExpress WPF tools really are a great way to allow devs to deal with layout less. Miguel pointed out that the pain points in the native .NET DataGrid control for WPF is an area where the DevExpress grid really shines. I think investing in a good control library can be the most well-spent money in a project.

Dani Diaz gave a presentation that focused on Microsoft’s efforts to support multitargeting .NET applications. I personally think that this will be the most important reason for developers to use the MVVM pattern. The approach in MVVM to support a loosely coupled architecture increases the ease of reuse by cordoning off direct GUI dependencies into the view. Dani’s presentation focused on WPF, Silverlight, and WP7 multitargeting. I actually think that is likely that two platforms not discussed in this event, IPhone and Android will drive MVVM adoption by allowing developers to work in a .NET shop and still target the most popular mobile platforms. Right now, iPhone and Android development with .NET means through use of Novell’s MonoTouch and MonoDroid development tools, As Dani pointed out, write once run everywhere is a myth. Users, myself included, want apps that behave natively to its OS. MVVM is the perfect pattern to allow multitargeting.

Dani talked about the upcoming Microsoft effort to support what they call Portable Library Tools. The Portable Library Tools are in a CTP stage right now but probably aren’t that useful yet. As Dani explained, Microsoft is still in the process of adding .NET framework elements that exist in a compatible way on multiple platforms. At the moment, the ObservableCollection class is not publicly supported by the CTP but it is expected that future releases will include this class. The ObservableCollection class is pretty essential in taking advantage of data binding.

The final presentation of the day was by Seth Juarez of DevExpress. Seth writes about his research in Machine Learning here. Seth’s approach was to give himself a crash course in Prism and share the results with us. Seth’s candor in talking about his experiences in dealing with Microsoft’s effort to support composite application development was refreshing. Prism can be a little difficult to get ones head around and appreciate. Seth showed that presenting a topic as a newby, it can be a good way to provide a quickstart to using Prism. Miguel also made a good point in his talk that Prism itself doesn’t provide any support for validation. Miguel is working on a MVVM framework built on top of Prism that adds validation. Seth used CodeRush throughout his talk illustrating just how much of a performance boost a developer can get by using a tool like CodeRush to support refactoring and minimize typing. It was pretty impressive although I still find the giant arrows that CodeRush uses to be garish and over the top. A little subtlety would be preferable, and less of a distraction.