RE: XForms data model: comments

Dear Rob

> Currently there's some debate going on in the
> working group about our data model.  Everyone agrees that XForms should
> support specifying a data model in XSchema.  There's some debate about
> whether that should be mandatory and exclusive (i.e required in all XForms
> implementations) or whether we should allow a syntax like that given in our
> datamodel spec as an alternative for people who aren't up to mastering
> XSchema and for implementations that don't have the horsepower to support it
> (e.g. mobile phones).

I'm not suggesting that XForms contains the hard bits of XSchema -
labelled as Advanced Concepts in the Primer. But I do want "simplified"
rather than "compromised".  Most of the suggestions I made were:

* to improve the completeness of the data model as regards a 
  _receiving_ script - ignored by a browser;
* to improve the ease-of-use for an XForms writer - extra facets => 
  more defaults (nostly boolean);
* acknowledging that the data model cannot be divorced from the UI
  without extra effort to turn all embedded text into codes. (+)

There aren't a lot of ways to create data.  You can either choose things
- booleans or categorical variables - or "enter" them via keyboard,
voice, graphical controls, whatever.  Extra datatypes mostly offer
a built-in validation function for an entered string, and thats it.
If you're going to support <number min="0" integer="true"> you might
as well allow "<positiveInteger>".  If you're going to support <number
pattern="-?\d*\.?\d*"> you might as well allow <float> - it'd be more
accurate, too (*).  I would imagine that by the time it reaches a user
interface, these have been mapped anyhow to a very small number of 
widgets + validation scripts.

That said, I think the key issue I'm struggling with on this, is the
relationship of the data model and the UI.  I certainly do not want
to specify them separately - though others should be able to - so I'm
looking for a way of mapping XForm datatypes to device-specific widgets
via stylesheets.

Yours
Neil Walker
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Neil Walker                     tel:   +44 (0) 1223 330379
MRC Biostatistics Unit          fax:   +44 (0) 1223 330388
Cambridge, UK                   email: neil.walker@mrc-bsu.cam.ac.uk
                                web:   http://www.mrc-bsu.cam.ac.uk 
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(+) Which might be necessary for internationalisation anyway, as Jerome 
    Marc commented

(*) See Jeffrey Friedl's "Mastering Regular Expressions", pp. 127

Received on Monday, 19 June 2000 06:14:04 UTC