The past seems to be popular these days. From VH1's nostalgia-laced "I Love the 70's, 80's, and 90's" shows to the popularity of "classic" musical artists (U2, Bruce Springsteen and the Rolling Stones coming soon to a city near you), retro is in. They're feeling a wave of nostalgia up at Microsoft too. But in Redmond, this wave marks the return of the rich client.

No, not the rich client you're familiar with—rich clients now have gotten "smart." How? In part, by the lessons learned in thin-client development. Over the past 10 years, Web application development has become the de facto standard for most programmers. "Thin was in," and we developers responded by dutifully learning our ASPs, J2EEs and PHPs.

So What's Wrong with Thin Clients?
In a traditional thin-client application, users navigate through a series of Web pages to perform tasks, and these tasks are realized primarily through server-side business logic.

What's wrong with this picture? Well, two things, really. First of all, despite the amazing things that we've been able to accomplish inside the browser, we still have to operate inside the browser. This creates some fundamental limitations to creating a rich user interface.

Secondly, the fact that our business logic exists on the server means that connectivity is essential. Lose the connection and the application is unavailable -- and work doesn't get done. Sure, we can focus our attention on improving server uptime, but typically some parts of the connectivity story are beyond our control (ever have your ISP decide to perform maintenance on your connection right before a deadline?) Besides, what about predictable situations in which connectivity is not present, as when a user wants to continue working while on a plane or at a remote job site?