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   Re: [xml-dev] DOM Level 3, more or less flexible than AS?

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On Thu, 2002-10-24 at 16:23, Elliotte Rusty Harold wrote:
> At 3:58 PM +0200 10/24/02, Eric van der Vlist wrote:
> >If we go back to DOM AS, the idea (as I understand it) was to completely
> >hide the schema system and rely on a query/request mechanism (the
> >application would just have asked to the AS if such and such update
> >could be done).
> No, that's not really how abstract schemas worked (or at least it's 
> not all they did.) They had a very detailed class hierarchy 
> describing, for example, the allowable content model of an element. 
> For example, here's what the ASElementDecl interface looked like in 
> IDL:
> interface ASElementDecl : ASObject {
>    readonly attribute ASDataType      type;
>    readonly attribute unsigned short  contentType;
>    readonly attribute boolean         strictMixedContent;
>    readonly attribute ASContentModel  contentModel;
>    readonly attribute boolean         isPCDataOnly;
>    readonly attribute ASNamedObjectMap attributeDecls;
>    ASAttributeDecl    getAttributeDecl(in DOMString name,
>                                        in DOMString targetNamespace);
> };
> This also failed to fit Schematron. And this has all gone away now.

Yes, this part was not that nice, the black box thing was what I liked
better and I am glad to hear it's still there.

> >IMO, this blackbox approach is the most generic API we can imagine and
> >it could virtually cope with any kind of "schema" system, including
> >Relax NG, Schematron or even one's own application.
> That's what DOM Level 3 validation is about. It's just been split off 
> into a more modular spec that was announced a couple of months ago. 
> See http://www.w3.org/TR/DOM-Level-3-Val/validation.html
> >By contrast, accepting the idea that an element or an attribute must
> >have a "type" seems to be a step backward.
> They are not required to. They are simply allowed to. Many elements 
> and attributes will have null types. (The exact representation of an 
> unknown type is still being discussed, but the working group clearly 
> understands that they can't assign a type to everything.)

Sounds better than the way I had read your text, then!
> >Relax NG doesn't impose this (and doesn't guarantee to report type
> >information consitently in all the cases) and Schematron has no
> >"built-in" notion of type either.
> >
> >Furthermore, I don't see how you can implement rules like Schematron
> >does so well with a type and a URI.
> Typing is about annotation. Validation is about checking conformance 
> to a schema. They are often confused, but they are not the same 
> thing. 

But annotations are (at least in the processing model implied by W3C XML
Schema and DTDs) binded to the information items through a schema and
this is problematic if the schema is a "non deterministic" Relax NG

> I think the new batch of specs gets this a lot more right than 
> the old ones did.  It's far more modular, and allows developers to 
> pick and choose what they need without locking them in to any one 
> schema language.
> >I think that we are moving from a concept which could have been amended
> >to support any type of schema and constraint to a concept which at the
> >end of the day might be more complex and is narrow minded and very
> >specific to the DTDs and W3C XML Schema approaches!
> I suspect if you look more closely at the family of DOM 3 specs, 
> you'll find that what you like is still there, and that a lot of 
> things you'd find very ugly and obnoxious have gone away.

Glad to hear it. I must admit I was reacting more to your statement (or
my understanding of it) that the fact to attach a type and a URI to an
information item was a step forward than to the specs themselves which I
haven't read yet.

To me, this is on the contrary the one of the basis of schema locking
and, unfortunately, most of the people seem to accept it as something

Thanks for the clarification! (and sorry to have over reacted to your


Rendez-vous a Paris (Forum XML).
Eric van der Vlist       http://xmlfr.org            http://dyomedea.com
(W3C) XML Schema ISBN:0-596-00252-1 http://oreilly.com/catalog/xmlschema


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