dSVG - A New Kind of Programming?

Gord Bowman writes "For anyone familiar with XML and, specifically, with SVG (Scalable Vector Graphics), you may be aware that SVG is increasingly being used for the creation of data-driven Web applications. But everyone has been doing so by handcoding script and/or XSLT, without the benefit of an IDE to help. Seeing such a need for a tool, my company (Corel) set about creating one." and 'lo, dSVG was born. Gord Bowman is the lead developer of dSVG and would like you to take a look at the dSVG specs (you can find the link, in the full article) and offer your comments.

"It quickly became apparent that while getting a grasp of XSLT is difficult and time-consuming, even more time-consuming was all the scripting it took to create the level of interactivity required on the client via script. Thus we set about creating a library of generic script functions that would assist developers in creating their Web apps. But it didn't take long to realize that this was no good--you can't data-map and transform (via XSLT) functions like you can markup. And, unlike markup, it's much more difficult to auto-generate and customize script via an authoring tool. So I set about designing an XML markup language, implemented with script (so as to work in any SVG viewer), which would describe UI controls and behaviours, so as to facilitate the creation of SVG-based Web applications.

It was a programmer's dream. I was essentially being paid to develop a new kind of programming language. One that, like XSLT, is XML-based but is more procedural in nature and thus easier for the average developer to grasp. It's also easier for non-developers to grasp it, thus bringing SVG and application development to a whole new class of user. A year later, dSVG (Dynamic SVG) was unveiled to the public as part of the Corel Smart Graphics Studio. And as of yesterday, the full dSVG 1.1 Specification and Test Suite became available for download.

The UI controls were designed to allow complete customization of appearance, and to allow for use with forms without being tied to a forms-specific model. The behaviors were designed to be generic and higher level than DOM methods, so as to be more intuitive to non-developers. The resulting markup language allows data-driven Web applications to be created with little or no need for scripting.

While script is very useful and powerful, markup has many advantages:

- markup is more easily understood by non-developers
- markup can be easily data-mapped and transformed using XSLT
- markup can be easily generated via an authoring tool and customized by the author
- markup is semantically meaningful, promoting interoperability on the authoring side
- markup can be standardized, thus helping the adoption of SVG

dSVG was implemented with script so as to work in different SVG Viewers. However, Corel has proposed dSVG to the SVG Working Group in the hopes that through a collaborative effort, dSVG will lead to the eventual creation of standard markup for UI controls and behaviors. These could then be natively implemented, bringing about even more advantages:

- faster
- less data to transfer
- less need for a script engine on small devices (which can take up a significant part of the footprint)

The dSVG 1.1 spec and test suite was posted for download with the goal of allowing the developers and non-developers to experiment with the markup and to provide feedback. This feedback will help me to improve upon dSVG and will also help the SVG Working Group to better assess how the developer community feels about such standard markup being added to the spec for the purpose of developing SVG-based Web applications.

I hope you will take the time to read through the dSVG spec, try out the test suite, and perhaps even create some of your own content. As the creator, I am obviously passionate and excited about dSVG. And having seen how quickly even non-developers can create Web apps, I feel certain that XML-based programming makes sense and is the way of the future. But being a long-time reader of Slashdot, I would love to hear what the Slashdot community thinks. dSVG may not lead to world peace, but I think it has the potential to change the fundamental way in which Web applications are created.

I look forward to hearing your comments.

Sincerely,

Gord Bowman
Lead Developer, Corel Corporation"

Comments

Future possibilities for improvements

[Gord Bowman]

Wow, this actually got posted. Cool. Let me first say that the dSVG 1.1 spec is still evolving. There's lots of room for improvements. For instance, there's an 'if' element, but no 'elseif' or 'else' elements yet. Those are obviously needed. I originally thought that a DTD could not (or should not) define an element as being dependent upon a sibling, but after talking with some XML experts at the SVG Open conference in Vancouver this past week, I see now that I was wrong. Another needed feature is some kind of a fallThrough="true|false" attribute for the 'case' elements within a 'switch' element--mimicking the 'break' statement but in a more XML-ish way.

One huge area for improvements is in the design of the skins. It seemed like a good idea at the time, but I now see that it has limitations both for performance and for the creation of custom UI controls. More on that in a separate comment...

The fact that dSVG is implemented with script is, for now, a good thing because it allows us to make changes to the spec without the viewer, since the implementation gets passed along with the content. And for previously written content, the Corel Smart Graphics Studio (CGSG) IDE will automatically convert from the old version of dSVG to the new version (via XSLT).

I have a big list of ideas for improvements, but it's back at home and I'm still in Vancouver for a few more days attending meeting (so I apologize in advance if I am not always responding in a prompt manner). I'm really interested to see what other developers think of the spec thus far and how it could be improved.

Re:Examples, Applications ?

[Gord Bowman]

You can find some demo apps at www.corel.com/smartgraphics/resources. As for apps created by customers, I don't know.

Re:Goodbye RFC, hello Slashdot

[Homology]

Shouldn't new standards be introduced using RFCs?

Well, from download page we have :

This file contains the proposal submitted to the World Wide Web Consortium (W3C) SVG Working Group to enhance SVG's support of enterprise application development for dynamic interfaces

along with an EULA whose length put even the MS one to shame.

However, I can't download the proposal without first agreeing to the EULA, so good riddance. If I was sufficiently interested I probably could look it up at W3C site.

Re:Goodbye RFC, hello Slashdot

[Gord Bowman]

dSVG is NOT a spec being proposed by the W3C. It's something we came up with ourselves for our product, and then proposed to the SVG Working Group. The concept of having "standard" markup for UI controls has been around a long time, but it hasn't happened yet. Maybe we're not asking enough people if it's what they really want or not. And if we want it, does it belong in SVG or should it be something larger and more generic in its own spec? And the idea of using XML for procedural programming is pretty new, I think. At least I had never found another example of it. Maybe someone else knows of one though. Regardless, I strongly believe in asking communities what they want rather than telling them what they want, and I also strongly believe in getting ideas and constructive feedback from people outside of the SVG-world. I couldn't think of a better forum than Slashdot to solicit that type of feedback.

Re:Can you please post the spec by itself?

[Gord Bowman]

Hmm. That's a good idea. It's actually my fault, really. They asked me if I could post just the spec and I said that the spec currently linked to the slides in the test suite and that I thought most people would like to actually play around with it. So they said, okay, but we'll need a EULA then. And I said, okay, and then went off to my SVG Open conference. So yes, I'll look into just posting the spec without all that legaleze stuff. It's the weekend, though, so I doubt it would happen until Monday.

Re:Waiting for SVG pop-up windows.

[Tet]

Is there something new you're offering (other than a different set of lawyers) that we should be noticing?

Let me see:

• The ability to navigate using the traditional back/forward buttons (although I believe the lastest versions of Flash support this to some extent).
• The ability to resize text so it's halfway readable.
• The ability to cut and paste text.
• The ability to use my standard ctrl-pageup/pagedown keys to switch between tabs in Mozilla (as well as other browser keyboard accelerators) without them getting intercepted by the Flash plugin.
• The ability for search engines to index the content I'm presenting.

There are many reasons why Flash is fundamentally flawed, and SVG is a much better solution in the long run. Only time will tell if the market is able to see that.