Re: [ubl-cmsc] XSD Derivation

["Eve L. Maler" <eve.maler@sun.com>]

Obnoxiously responding to myself...

At 09:58 AM 11/27/01 -0500, Eve L. Maler wrote:
>It seems that the big case of non-XSD-friendly extension, and perhaps the 
>only really juicy example, is addition of elements to places in content 
>models other than the end.  Particularly for machine-to-machine 
>applications such as UBL, subelement order shouldn't carry significant 
>semantics, such that adding things only to the end should be 
>safe.  However, are we missing any use cases for adding things to the 
>beginning or middle?

Someone else mentioned the other juicy kind of extension we'll need (I 
can't find it in the thread) -- extending code lists.  Believe it or not, 
there is no obviously clean way to do this in XSD.

The following proposal that I co-authored with Dave Orchard for the SAML 
group's consideration has a section at the end on "Schema Extension 
Techniques", specifically addressing extension of enumerated lists:

   http://www.oasis-open.org/committees/security/docs/draft-orchard-maler-assertion-00.pdf

(BTW, note that I actually didn't agree with several things in the 
proposal!  My goal was to break several logjams at once by offering 
something different.)

This may be the only case so far where it's easy to imagine implementing 
the feature as a transformation rather than an XSD customization layer.

         Eve
--
Eve Maler                                    +1 781 442 3190
Sun Microsystems XML Technology Center   eve.maler @ sun.com