Building WPF and Silverlight applications can be challenging, especially for those new to the technology. Building clean, maintainable, extensible, testable, loosely coupled ones— with no idea where to start—is close to impossible. In late 2007, I was privileged to get a call from Glenn Block at Microsoft asking if I was interested in working with the Microsoft patterns & practices team on a project that would become the first release of Prism, which was released as the Composite Application Guidance for WPF in June 2008.

I had been working with WPF on complex customer applications, trying to figure out the best practices and patterns on my own. This was a fantastic opportunity to provide some guidance and feedback to the team on what mattered, what worked, and what didn’t, in real customer apps that I had worked on. I had worked with various patterns & practices teams before as an external advisor, but this was my first opportunity to come in as a consultant and participate as an integral part of the team.

It turned out to be a wonderful experience for me. The team included some of the most intelligent, creative, and fun individuals I have had a chance to work with in this industry. The maturity of the team’s development process, the effort that they put into collecting community input and keeping the community involved throughout the development process, and their collective design and coding prowess and professionalism made it clear from the start that the right people were working on guiding the .NET development community on the right way to build apps. I learned a ton in the process and hopefully contributed something that helped make Prism a better product. So, naturally I was delighted when I got the chance to work closely with the team again on the release of Prism 4.

Prism 4 offers many things to many people. One of the biggest misconceptions is that because it offers so much, it is too big or too complicated for smaller apps. One of the early design goals of Prism was to keep the concerns of Prism separated in the same way Prism helps you separate your own application’s concerns in the presentation layer. I think the team did a great job of doing that, and you can easily use just commands, or just events, or just modularity, or just UI composition or some combination of the above in ways that are minimally intrusive to the rest of your application code. Add to that the new Model-View-ViewModel (MVVM) pattern guidance, Managed Extensibility Framework (MEF) integration, and navigation functionality of Prism 4, and you have a great set of tools in a toolkit that can help you develop apps of any size.