Usage of wsu:Id and xml:id in the WS Policy XML Schema

This mail is based on some offline conversation between Asir, Chris,
Paul and me.

The XML Schema document for the WS-Policy LC WD is not yet updated. The
reason is that the latest revision
http://dev.w3.org/cvsweb/~checkout~/2006/ws/policy/ws-policy.xsd?rev=1.6
has a problem with the schema update for the resolution for
http://www.w3.org/Bugs/Public/show_bug.cgi?id=3560 (enable the usage of
xml:id):
 
If you use xml:id at the <Policy element> in an instance with the
current schema, you will get an error. You can't use xml:id, typed as an
ID, on an element which has an ID attribute (like wsu:Id) specifically
declared for it.

There are three solutions for the problem:
  a) publish two flavors of the schema, one with xml:id, one with wsu:Id
  b) declare two subtypes which are accessible via xsi:type:
<Policy ... xsi:type="xid-flavor" xml:id="boo" ...> versus <Policy ...
  xsi:type="wsu-flavor" wsu:id="boo" ...>
  c) delete the explicit reference to <xs:attribute ref="wsu:Id"/> .
This would make both xml:id and wsu:Id extensibility points.
  
I have a high preference for c), including a note in the WD to warn
schema users (don't use other ID attributes than these two), to avoid
the confusion created by deleting the explicit reference to
<xs:attribute ref="wsu:Id"/>.

I have not opened an issue on this and not reopened 3560, since the
normative text has precedence over the schema anyway. Hopefully we can
resolve this without a LC issue.

Felix

Received on Friday, 8 December 2006 12:15:58 UTC