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From "David Bau" <David....@bea.com>
Subject RE: XML Beans details
Date Thu, 03 Jul 2003 22:38:51 GMT
> On Thursday, July 03, 2003 5:23 PM, Neil Graham 
> <neilg@ca.ibm.com> writes:
> >
> > How does this approach handle things like the schema unique particle
> > attribution or element declarations consistent constraints?  
> > Clearly you
> > could parse schema documents simply using information from the
> > schema-for-schemas, but using that alone, surely it's not 
> possible to
> > handle all conditions imposed on valid schemas by that spec.
> Ah, Neil, you're a man in the trenches with Schema along with me!

My apologies Neil,

Just after hitting "send" I realized I think I answered a
different question than the one that was asked.  Let me try again.

We have three layers the compiler handles.  Basically the compiler's
job is to go from (1) -> (2) -> (3).

(1) Schema syntax
(2) Schema type system in-memory
(3) Schema metadata binary persistence format

Layer (1) is handled by schema-for-schema as described in the
previous mail.

Layer (2) is where we do type resolution and verify all the
semantic rules of schema that are not imposed by s4s for
example particle valid (restriction) and element consistency
and actually many many many other rules.

I think layer (2) is the answer to your question.  Layer (2)
catches the valid-schema errors that are not syntactic-validation
issues.  Building layer (2) is the core of the compiler.

Once we pass layer (2) then we have a fully valid schema
type system and can persist it as layer (3).

Layer (3) can be loaded directly at runtime for high-speed
schema validation.  [basically it reconstructs (2) on-demand.]
Or at runtime if you choose to build the schema types via
layer (1)  and (2) you can do that too.

David Bau
XMLBeans Architect

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