In this interview made during ALT.NET 2008, Glenn Block answers Greg Young's questions about Prism. Among others, Glenn talks about what is Prism, the differences between Prism and CAB, the architectural challenges met, the customers' feature requests.
According to Glenn:
Prism is a set of guidance coming out of Patterns and Practices for building composite applications in WPF. And what is a composite application? It’s essentially an application that is dynamically composed from a set of different pieces, and basically composite applications address really complex enterprise application scenarios.
Another composite UI framework from Microsoft is CAB, and it was developed for WinForms. Prism may seem as a duplicate framework, but Prism was built for WPF (Windows Presentation Foundation) and it did not take a single line of code from CAB, according to Glenn.
Talking about architectural challenges of Prism, Glenn mentions "modularized development" and that means "being able to develop my application as a set of modules that can be separately developed, tested and deployed". The other major architectural challenge mentioned by Glenn is "UI composition" referring to "an application that is dynamically composed of a set of pieces, and they need to be able to work with each other in a coherent fashion".
During this interview Glenn also speaks about the feature requests received from the customers. Unlike other products, work on Prism started after a meeting with the customers where they could present their concerns and requests for a UI composite framework, which were considered when Prism was later developed and built.
InfoQ covered Prism in a recent news story. The entire interview is 18 minutes long.