So when should you choose to build a smart client rather than a web application (or in addition to). The typical answer I’ve seen is when extreme usability is required. As AJAX techniques get more mature, I think this will become less of a consideration.
As I thought of it more, it hit me. The same thing Jeff Atwood said about strored procedures, “Stored Procedures should be considered database assembly language: for use in only the most performance critical situations†applies to applications.
Smart Clients should be considered Application assembly language: for use in only the most performance critical situations.
This is why you won’t see the next version Halo running in a browser (though you might see the first version someday). This is also why you won’t run Photoshop in a browser. Performance is critical in such applications.
There are other important considerations as well, such as security. I wouldn’t run an RSA key ring in a browser. Also apps that constantly run and perform a service on your machine. For example, system tray icons, though even that concept seems to be changing.
Anyways, I need to chew on this some more. At this point in time, usability is still a concern. That is why I run a client RSS Aggregator and use w.Bloggar to post to my blog.
Although the deployment issues for web-based applications are great, the development environments for AJAX applications pale in comparison to writing a rich UI. There’s just something about writing object oriented compiled code that makes me cringe at writing everything as javascript.