This time we will look a little closer at an important change on the user interface side of the architecture. I'm talking about applying the MVC pattern (or rather its variation, the MVP pattern), and even if this change is far from recent (both mentioned patterns have been around for quite awhile), the importance of applying this pattern has increased. The reason is an increased focus on automatic testing, TDD, and continous integration. By applying the MVC pattern, the bulk of the logic of the user interface (located in a "controller"), can be tested independent of the actual user interface. This, and the more traditional benefits, that you can apply different "views" (user interfaces or more general, channels) to the same user interface logic, makes the MVC pattern a common part of any modern software architecture.

If you do some browsing on the Web, you quickly find that there are many implementation of the MVC pattern, but there are not that many specific to Windows Mobile developers (although most .NET implementations should migrate without much hazzle). One great initiative was the MCSF by Microsoft's patterns & practices team, which included a solid implementation of the MVC pattern (among many other) that was migrated from various application blocks for the full .NET Framework. However, the MCSF was so solid that it took a great deal of time to learn before you could be productive. Also, the MCSF is now a bit outdated, and judging from the lack of news or updates about it, my hopes are not up.

The community (and me too) wanted something simpler, and in some projects, I have used a very simple and straightforward implementation by my former fellow MVP, Alex Yakhnin (he's now employed by Microsoft), that he published as a small blog series last fall (see part 1 and part 2). In those blog posts Alex also showed a simple solution to a very common problem when building great UX for Windows Mobile, and that is to handle the caching of forms. Loading a form is an expensive task in terms of performance, and therefore it's necessary to cache the forms in memory.

In upcoming posts, I will continue with more of my thoughts on the changes in mobile architecture, and of course also some code samples to show the theory in practice.