I was chatting with Chris Double the other day about the growing number of hits in our referrer logs having to do with "continuation based web frameworks", and how awkward a phrase this is. Not only is it long to write and say, but it rather misses the point: it describes a particular implementation technique without saying anything about what the technique achieves. You can build Seaside-like frameworks without having full first-class continuations (this is what UnCommon Web does, and arguably what ViaWeb did years ago); you could
also build a web framework that happened to use continuations but didn't have Seaside-
like session flow. So I proposed that we stop talking about continuation based web development and start talking about "modal web development" instead.
Why "modal"? Well, first of all, it's short, and it's an adjective instead of a noun, both of which are bonuses. Second, it brings to mind one of the best examples of Seaside-style interaction, which is the modal dialog box. In pretty much any desktop GUI environment, there are a number of simple functions or methods that bring up standard dialog boxes (file selection, color picker, notification, confirmation), block the current thread until they are dealt with, and then return the user's input. These are supremely reusable - the file selection dialog doesn't know what you're going to do with the file, just that you need one, and so it can be written once by the toolkit developers and used unchanged by hundreds of applications. They are also extremely easy to use - if at some point during a computation you realize that you need a file before you can continue, you just write something like
end = chooseFile("Pick the end point of the morph", "*.jpg")
and keep going from there. One major advantage of Seaside and similar frameworks is that they let you write webpages that act much like modal dialogs, and reap those same benefits of simplicity and reusability.
Now, I know that people instinctively flinch when they hear "modal UI", because in a desktop context we've all had "modeless good, modal bad" drilled into us. I actually don't believe that this applies in the web context, but I won't go into that now. Instead, I'll just say that at least in the specific case of Seaside, the point isn't that
you are forced into using a modal style, but rather than you have it available when you need it. Seaside has an excellent event model and uses it extensively, far more in most applications than it uses modal semantics. However, you can have real modal interactions when you need to, whereas with pretty much any other web development
technique you can't, ever.
So this is a blogging experiment: how long before we start seeing "ANN: new modal web
framework" and "Modal web dev sux0rs!" posts? Is "continuation-based" already so entrenched a term that it won't catch on? Or will the opposite happen: no longer tied to a specific implementation, will "modal" get so widely and over-generally applied that
it's rendered as meaningless as "MVC" or "object oriented"?
Note: I originally wrote this about a week ago, and then decided not to post it because some people I respect really didn't like the term. However, Chris Double just let the terminological cat out of the bag, so what the heck: let's see how it plays with a wider audience.
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