Back at Mix'07 when I first heard about XBAP I thought it could prove very handy in coming years and I was expecting to see many applications in coming months build on XBAP, but the last time I had a healthy discussion about XBAP developers was in Nov'07, well that was about 2 months ago, as it happens I had that discussion just before we heard about Silverlight 2.0, so why is no one interested in XBAP anymore?
XBAP only came to existence because Silverlight (at the time 1.1 Alpha) didn't provide the basic user controls, binding options, and many restrictions on Silverlight usage with assets and/or web services, Silverlight applications mostly lack the infrastructure to use .NET framework so the only option was XBAP.
XBAP was simple and neat idea build on WPF but when it come to universality, it lacked cross platform compatibility over Mac/Linux. But when Silverlight 2.0 was announced with user controls, binding, grids and to lift many restrictions like cross domain calls, and providing support for web services methods like SOAP/REST, the idea of developing XBAP applications just began to fade away.
So with Silverlight 2.0 Beta 1 to be released in next 6 weeks what is the future of XBAP? Its not a simple question and personally I am a bit optimist and would love to say good byes to XBAP but ever since Mix 07 Microsoft has disappointed me again and again with Silverlight, I am hoping the Mix 08 will change all that, but I am sure that after a few months after Silverlight 2.0 is released developers might again start to talk about XBAP but this time for some other features that Silverlight might lack mostly with 3D or networking supports like sockets or VOIP.
After Mix08 and Silverlight 2.0 Beta 1 is released I'll try to post the features that Silverlight 2.0 lacks and in what situations would XBAP could be used, if at all. Please stay tuned.