Thursday, November 08, 2007

Quick Note : I just had a revolution in my thinking, triggered by Enso but influenced by several other recent trends.

You write Enso "extensions" as XML-RPC servers sitting on your local machine, register them with Enso and it calls them using XML-RPC. I tried the example from the tutorial and it's very cute and simple. So I've decided this may be a way forward for the dilemma which has kept the "new SdiDesk" on hold for several years(!!!)

If you remember, the issue has been whether the new SdiDesk should be a "web"-application (accessed through the browser) or a desktop application? And how to implement the UI.

The problem with the "browser" answer has always been : "but how to do the network diagramming bit?" - which requires interactive vector graphics. SVG doesn't seem quite stable or cross-browser enough. Canvas isn't cross-browser. Flash is proprietory.

The problem with the "desktop application" is, well, the many rival Python GUI libs with different degrees of maturity. And the question of getting them to work cross-platform.

A meta-problem : I just don't have time and energy to go through learning lots of different GUI frameworks to decide which I want to use. And the ideal answer to the browser / desktop question is probably "both" which doubles the amount of work.

In fact, one of the motivations for GeekWeaver is to see if I can use it define a higher-level UI description that can be compiled down into both XHTML and a GUI widget-set.

Of course, with XUL, Open Laszlo, Adobe Flex, XUML etc. lots of people have been looking at something like HTML for defining desktop apps. too, but the free Python frameworks don't seem to have caught up with that yet. XUL sounds most promising especially with the open sourcing of Active State's Komodo ... but that's also a big complicated thing to even start looking into.

Anyway, inspired by the Enso extensions and Bruce Eckel's interesting example of hooking up a Python XML-RPC server behind an Adobe Flex application I've been wondering about blowing the project apart entirely into a number of services connectd only XML-RPC or something more ReSTful.)

So there'll be a WADS (SdiDesk PageStore) service, a GeekWeaver interpreter service, a "user navigation history service" etc. Even the glue which ties all this together will be another service that's neutral about the user-interface. Effectively the model, view and controller will be completely separate programs. (I know, I know ;-) )

Then there'll be a variety of different types of access with different UIs.

Now that Adobe's AIR has put Flash on the desktop and made it a serious rival to the Java virtual machine - I *am* tempted to put some time into learning it. It would give me a reasonable GUI widget set (including TreeGrid, yay!) and the vector graphics needed for networks. It will run both on the desktop and in the browser and on Linux, PC and Mac. The tools are free-as-in-beer (Flex beta) or free-as-in-speech (Open Laszlo). It's also possible to imagine generating the Flex XML or the Open Laszlo format directly from GeekWeaver. (Aside : I wish ActionScript hadn't borrowed quite so much from Java, but still, I'd only be using it for the front-of-the-front-end UI stuff.)

Then I want to experiment with Enso access - for example, Enso commands like "page HelloWorld" or "pagehistory ChocolateCake"

And there'll be web-browser access probably through a "gateway" that accepts http requests and spits out HTML for a browser. The only thing I don't know is whether I *really* should be using WSGI somewhere here.

Anyway ... that's a quick update of my thinking this week ... tune in soon for the next GeekWeaver release (really, it's coming together, and gonna be very powerful). Then it's back to work on this larger project.
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