Its fun to watch the two leading RIA platforms evolve. Microsoft’s Silverlight and Adobe’s Flex are similar in the general but different in the particular. Its easy for the zealots of one camp or the other to accuse each of “stealing” ideas from the other but I feel that similarities are just the product of the evolution of software in general. Just as all OOP languages have evolved with Interfaces, inheritance and the like, the RIA offerings all use the declarative and code behind model with a plugin runtime.

With Windows presentation Foundation (and inherited by Silverlight), Microsoft introduced “lookless” controls which define their behavior without worrying about how it will look when rendered. The controls have a default look which can be radically changed by touching only the part that dictates how the control looks, not how it operates. The true beauty of this separation of the functionality of a control from the way it looks is realized through the use of designer oriented tools which let designers work to make stunning looking results without worrying about trouncing the control’s logic or having to drop down into code.

With the entrance of Flash Builder, Adobe’s successor to Flex Builder 3, the existing “Halo” component set is being augmented with the new “Spark” components which take advantage of this code/design separation paradigm that Silverlight uses.

This is a logical evolution as Adobe want’s its new designer tool, Flash Catalyst, to be able to tweak the look of a control without worrying about its functionality just as Microsoft’s Expression Blend 3 tool currently does. As companies race to outgun each other with more expressive RIA applications, design rules the day. In order to create these beautiful works of art, with all the subtle transitions and effects, designers must drive the show and they need tools to do so without dropping down into code. Thus to stay cutting edge we have Expression Blend and soon Flash catalyst.

Looking at Adobe’s path, Flex has been the leader in RIA technologies to this point, especially with the very successful existing Flex 3 product. But the current state of affairs with their component system (Halo components) needed to be addressed (via the new Spark components) as the Flex components have their look and feel mixed in with the logic of the component. If the design comps call for highly customized components, always savvy Flex developers roll up their sleeves and “Monkey patch” the Flex source code (which is generously released by Adobe) and change it to suit their needs. Flash Builder’s usage of lookless controls will go a long way towards ending the need to customize the control as the look can be swapped out without messing with the code.

Design teams are in the cat bird’s seat nowadays as both camps evolve their offerings driven by the “improved designer/developer workflow” mantra. Only good things will come from all the innovation resulting from these companies trying to drive profits by offering better products. Namely, we will have better and better tools to work with! Healthy competition is great! – Cheers!