So today I'm taking a pretty deep dive into XPages development as it currently exists in the Domino Designer 8.5 Beta. What continues to impress me is the success of Phillipe and Maureen -- and of course their entire teams -- at integrating the things learned in the process of building newer things like Portal with Maureen's unrivaled depth of understanding when it comes to the root core problems we struggle with in Domino and Notes development. There are dozen or so places as you get deeper and deeper into doing development with XPages where you realize "oh, that's what ______ should have been!"

For example, the idea of a "Custom Control" is what a "Subform" would be if it could really start all over. It is an entirely self contained XPage in its own right, but designed to be placed directly into or on other XPages -- and you can use it multiple times on the same XPage without conflict because it is self contained. It can expose properties to the parent page so that the control handles different things on the page according to what your code wants it to handle. So, its a bit like a subform except that is totally self contained, applicable multiple times on the same XPage, externally controlled by its parent page, able to contain its own bound data sources.

One example might by to create a custom control which is designed to show data from a single document from a view. It may have a much more complex layout than you could do as a view row. The specific document to show could be tied to an externally exposed property so that when you embed the control on an XPage (remember, the control is itself just an Xpage) you can define from the parent page at runtime the column key or the unid or whatever.

Then, expand that by putting your custom control on an XPage in a panel that you then define as repeated for each document in the view. BANG, you've just created the most complex view you can imagine on the XPage.

There is so much seriously cool stuff in XPages that as far as I'm concerned, if you're writing Web Based applications on an 8.5 server they're the only way to go. They deprecate about 80-90% of the way you write Domino web apps before XPages. I suspect that when they finally work in the Notes client, they'll have the same impact.