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Re: [ISSUE-37] New proposal on RIF interoperation with XML data and XML Schemas

From: Christian de Sainte Marie <csma@ilog.fr>
Date: Wed, 18 Mar 2009 10:25:01 +0100
Message-ID: <49C0BDED.9090308@ilog.fr>
To: kifer@cs.sunysb.edu
CC: RIF WG <public-rif-wg@w3.org>
Michael Kifer wrote:
> 
> But more generally, an element can have an anonymous type.

</chair>
What is the problem, if an element, say, A, has an anonymous type?

?x#A selects all the elements named A, and, if there is no type named A, omly the elements named A (keeping the substitution groups aside, ofr the sake of that discussion). If there are several elements named A, with different types, then you select them all. And, so, what, as long as it selects only elements named A, nothing else? If this is not what you want to do, you do not use ?x#A in that case.

The big problem with my current proposal is that exactly the same construct can have two different meanings (select by element name and select by type name) and there is no way to distinguish between them.

What you seem to point out, if I understand correctly, is that my current proposal, also, lacks the expressive power to discriminate between elements with the same name and different (possibly anonymous) types.

That is a different kind of flaw, I think: first, the level of expressiveness that is useful is arguable (that is a point where the 80-20 rules apply in standards; and that is what I had in mind, when I refered to that rule in an earlier email); second, new constructs can be added, if expressive power need be increased.

> Also, are you assuming that an xml doc is always associated with an XML schema?

No, I do not assume that an XML doc is always associated with a schema. I require that you have at least one of: an XML instance doc, a DTD or an XML schema. Only if you import a non-XML/RDF/OWL data document, do I require that it is associated with a DTD or a Schema.

> If not, then things become too hairy to contemplate :-)

Why is that?

I would say, to the contrary, that that big flaw in my proposal does not apply to the case where you have only an XML data document, with no schema associated: in that case, you cannot select elements by type, but only by name...

What am I missing, this time?

> In that case, I think, only Gary's proposal or equivalent (eg,
> XPath-based methods) would work.

No, this is exactly the case where Gary's proposal does not apply: Gary's proposal is about mapping schema components to RIF frames. It requires an XML schema.

My proposal maps components of a (possibly virtual) XML instance document on RIF constructs. It does not require an XML schema (it requires at least one of an XML instance document, a DTD or an XML schema).

That is not to say that Gary's proposal is not what we should do. As much as I like my own proposal, I am undecided.

<chair>

Christian
Received on Wednesday, 18 March 2009 09:25:55 GMT

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