xml-dev - Re: XLink a special case in the self-describing Web?

[Paul Prescod <paul@prescod.net>]

"Steven R. Newcomb" wrote:
> 
> ....
> 
> .... Is the idea of "equivalence classes" that all of
> the constraints contributed by X:Foo and Y:Bar are fully (and
> automatically) inherited by Garp, and that therefore it's only
> necessary for instances to be validated against Garp, rather than
> against X:Foo and Y:Bar?

As I understand it, that is the idea.

> If the passing of constraints to equivalence classes is automatic, can
> the declaration for element type "Garp" further constrain X:Foo's
> constraints and Y:Bar's constraints?  This is also a business
> requirement for distributing control over industrial vocabularies.

Yes, this can also be done.

> > > (2) XLink is now just attributes; the element type can be anything.
> > >     This permits a single element to be recognized as an XLink and as
> > >     whatever else it may be.  (Whatever else it may be, it may still
> > >     only be one element type in one single namespace, as far as I
> > >     know.)  This is a kind of sleight-of-hand: XLink elements are
> > >     still XLink elements; we still expect certain combinations of
> > >     attributes to appear in certain contexts and not in others.
> >
> > Theoretically XLink could use the equivalence class mechanism. So
> > yourlink would be defined as a "kind of" xlink. But I haven't tried it
> > so take that with a grain of salt.
> 
> I'm confused.  I thought equivalence classes pertained to elements.
> The current XLink draft doesn't define any element types.

That's what I mean by "theoretically". The current XLink draft predates
schema equivalence classes. XLink is so far behind schedule that I would
be amazed if its creators have the stomach to reorient it based on more
generic facilities.

The only "snag" is that XLink is built around the XML philosophy of
non-dependence on external schemas. XLink users will be encouraged to
use XLink attributes inline, no matter how poor that idea is in
practice.

-- 
 Paul Prescod  - ISOGEN Consulting Engineer speaking for himself
Just how compassionate can a Republican get before he has to leave the 
GOP and join Vegans for Global Justice? ... One moment, George W. Bush
is holding a get-to-know-you meeting with a bunch of gay Republicans.
The next he is holding forth on education or the environment ... It is
enough to make a red-blooded conservative choke on his spotted-owl
drumstick.     - April 29th, Economist



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