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RE: Schema concepts (was Re: W3C public lists (was Re: The Power of Gro

• From: Matthew Fuchs <matthew.fuchs@c...>
• To: "'Michael Rys'" <mrys@m...>, XML-Dev Mailing list <xml-dev@x...>
• Date: Thu, 10 Feb 2000 18:05:12 -0800

Well, maybe partly.  I think I'd say "This is _one way_ you can interpret
the distinction...."  I think you're shooting a gnat with an elephant gun,
certainly with regards to how the decisions came about.  So far, no one has
shown me how all the functionality of elements in xsdl cannot be provided
through the usual OO mechanisms (including the "substitutability" conditions
- I hesitate to use that word in the context of xsdl).  Like the parallelism
axiom - throwing out the assumption does not create a contradictory model,
as far as anyone's shown me.  

As I've said, though, there is a way to unify them and I hope to write that
up soon.

Matthew

> -----Original Message-----
> From: Michael Rys [mailto:mrys@m...]
> Sent: Thursday, February 10, 2000 5:12 PM
> To: Matthew Fuchs; XML-Dev Mailing list
> Subject: RE: Schema concepts (was Re: W3C public lists (was Re: The
> Power of Groves))
> 
> 
> In addition, I would like to point out that in Object Data 
> Models (including
> the later releases of ODMG), there is a difference between 
> structural type
> lattices (classes in C++, aka type inheritance) and 
> semantical collection
> hierarchies (collection of objects that satisfy certain 
> conditions that are
> either necessary and sufficient or necessary, aka as class 
> subsumption). A
> common condition on such a semantical collection is, that all 
> members are of
> the same base type (the so called member type). This is 
> exactly how you can
> interpret the distinction between type (structural 
> description) and element
> (semantical role).
> 
> Best regards
> Michael
> --
> Michael Rys
> Microsoft XML Repository -- We store the Web and more
> mrys@m..., rys@a...
> 
> > -----Original Message-----
> > From: ht@c... [mailto:ht@c...]
> > Sent: Thursday, February 10, 2000 5:30 AM
> > To: XML-Dev Mailing list
> > Subject: Schema concepts (was Re: W3C public lists (was Re: 
> > The Power of
> > Groves))
> > 
> > 
> > Stefan Haustein <haustein@k...> writes:
> > 
> > > If that holds not only for Simon, I would like to ask why 
>  XML schema
> > > needs both <element> and <type>. It looks like they both 
> correspond
> > > to the class concept in OOP. See
> >
> > Because several elements may share a type:  this is 
> illustrated in the 
> > lengthy example in chapter 2 in the current PWD [1].  If 
> having looked 
> > at that you still don't understand, please come back with a question
> > based on that example if possible.
> > 
> > ht
> > 
> > [1] http://www.w3.org/TR/xmlschema-1/#concepts-types
> 

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