extending xsd:element attributes - again

As a relative newcomer to XML I hope what I am asking below makes sense. I
am sure if it doesn't I will be enlightened in due course.

Back in July and August there were threads initiated by Casey Mullins and
Dave Gross concerning personal namespace attributes to the XML Schema.
Namely defining a schema schema that allowed you to use your own attribute
names and values in the xsd:element entity. Whatever replies there were,
were of the variety "Yeh that looks correct", or "As I understand it, you
can do what you have done", followed up by "but I don't think any of the
validators will handle it" - or similar responses.

As someone who is trying to extend the attributes of the XML Schema in a
pretty extensive way, I really need to know if what I am doing is valid,
makes sense, or is the best way to do it. The last of these will come with
experience but the first two need reliable software that will help me.

I too want to be able to add attributes to my schema definitions. I
already use a "dictionary" to define a data model and these dictionaries
can even contain user defined imbedded methods. Needless to say our system
is not based on XML and predates XML by many years. However part of our
system can be mapped to an XML Schema, but with some extensions. In our
"dictionary"  I can declare a data object's structure extensively, as in,

TypeContainer = "Matrix" (or possibly List, Tuple, Vector etc)
ContainerDimension = "[3][3]" (or whatever).
TypeContainerElements = "Real" (integer etc)

In the context of XML I think (at this stage) what I want to do is,

<xsd:element
  name="TransformMatrix"
  me:TypeContainer="Matrix"
  me:ContainerDimension="[3][3]"
  me:TypeContainerElements="Real" />

The last attribute is probably best handled by xsd:type since it will
cover everything I need. I think I can define my new attributes with
either their allowed enumeration or a pattern that matches against a
legitimate string.

(1) Can anyone tell me is there a validator that will read my schema
extensions, and when given an instance schema will validate that the new
attributes are valid AND that the attribute values are valid?

(2) On a related topic, is it possible for me to define in a schema schema
an new entity say <DictionaryDefn> that extends the xsd:element entity, so
that in the instance schema, when the validator sees <DictionaryDefn> it
knows it has to process it in exactly (in a semantic sense) the same way
as an the xsd:element entity. I am pretty sure I know how to do this in a
syntactic sense but if the validator doesn't appreciate I am subclassing
off the xsd:element (its attributes AND its methods etc) there is little
point in doing it - make sense?

(3) If the answer to (1) is positive, then the next thing to do is to
validate an instance document with my schema. I have a clear cut
specification for what a Matrix must look like as data. How does the
validator know? If in my schema I define an entity to be Integer then the
validator presumably can look at the data instance of that entity and
verify it is indeed Integer. How can it do this for my "Matrix"? Perhaps I
am asking too much of generic XML validators.

-- 
cheers

Nick

--------------------------------
Dr Nick Spadaccini (Acting Head - 2001)
Department of Computer Science &            voice: +(61 8) 9380 3452
Software Engineering                          fax: +(61 8) 9380 1089
University of Western Australia
CRAWLEY, Perth,  WA  6009                  email: nick@cs.uwa.edu.au
AUSTRALIA                                 w3: www.cs.uwa.edu.au/~nick

Received on Thursday, 6 September 2001 04:20:33 UTC