Re: Document adaptation using DIAL and DISelect

Hi Cameron,

Thanks for your comments. Let me try and answer your questions
(everything below my own opinion, not the WG's).

DISelect is open in terms of XPath access functions: we're defining a
few, based on CSS media queries, but others can be added, which can
return more complex layout information, like the css-box-height
function you describe. However, note that the kind of information that
those functions return must be able to be sent to whatever adaptation
engine will process DISelect expressions. For instance, an adaptation
engine that sits between a web server and your mobile phone (on one of
your mobile phone provider's gateways, say) may get values out of the
cssmq-width function from delivery-context mechanisms such as CC/PP,
or WURFL. It's less obvious how that can happen with layout functions.

Moreover, DIAL is an authoring language, and so is DISelect
markup. The reason why DISelect is designed to be embedded in the
document, and not an extension to CSS, is that it's all about
selecting content, not style. sel:select will be used for selecting
between different versions of a text (long or short, typically), but
not to change the colour of a page. Of course you can put a
<sel:select> around a <style>, but (again, in my opinion) that's going
too far and embeds styling and presentation like it's 1995.

If the language DISelect is embedded in is SVG, then things are
different, however. It's going further than the DI working group
envisaged, but since SVG is already presentation and content
(arguably), one could imagine DISelect markup be used, along with new
XPath functions.  I don't believe the WG has ever considered that use
case. At least it hasn't discussed it for the last year and a half. We
will keep this use case in mind though, but I doubt we would be adding
more features to do things as complex as constrained SVG.  But when we
discuss the Layout section of DIAL, I'm sure we'll recall your email
and will consider your ideas.

Cheers,

Max.

Received on Monday, 17 July 2006 15:31:57 UTC