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RE: LANG: Moving issues 5.6 and 5.14 forward

From: Massimo Marchiori <massimo@w3.org>
Date: Tue, 24 Sep 2002 17:34:48 +0200
To: "Jeff Heflin" <heflin@cse.lehigh.edu>, "WebOnt" <www-webont-wg@w3.org>
Message-ID: <NGBBJNKIMLOPPCFHEJEMOEIJDAAA.massimo@w3.org>

> The Proposal:
> ---------------
> I propose that imports and versioning information be declared outside of
> RDF. In particular I propose the we have an owl:Ontology tag that wraps
> all OWL ontologies. The content of this tag is import and versioning
> tags followed by the RDF content of the ontology. This has the nice side
> effect, that the content of an ontology is finally nested within an
> ontology element.
>
> Here's an example:
>
> <owl:Ontology xmlns="...">
>    <!-- multiple imports are allowed in separate elements -->
>    <owl:imports resource="..." />
>    <owl:imports resource="..." />
>    ...
>    <owl:priorVersion version="..." />
>    <owl:backCompatWith version="..." />
>
>    <rdf:RDF>
>         <!-- all of are class and property statements go here -->
>         ...
>    </rdf:RDF>
> </owl:Ontology>
>
> Thus, RDF parsers can just ignore the surrounding XML content and still
> get "partial understanding" of it. OWL parsers can use this extra
> information in whatever ways are deemed fit for owl.
<snip/>
> If we can get agreement on this, then I think we can start tackling the
> issue of how do we define the meaning of imports.

The point is that in order to find a solution, we need (well, it would be better, say) to know better what the meaning of imports
and versioning are.
At high-level, there are two choices, as been discussed, to include these things:
+ put the thing "in RDF"
+ put the thing "outside RDF"
These don't come for free, on either sides. Since we're on it, the "outside RDF" has as major impact the fact that, as we're using
RDF as exchange syntax, the "thing" cannot be exchanged, and it's bound to its local instantiation.
Now, don't get me wrong, two weeks ago on the call I've advocated heavily, with Peter, against the dangers of putting things "in
RDF", so I'm not saying the other spectrum is the one to choose too, just pointing out the implications.
So, back to the issue, putting things "out", while nicely avoiding some RDF troubles, has some drawbacks too. Whether these are real
drawbacks or not, depends on the meaning of the "thing", so I don't think we can easily choose one or the other (or similar
variations) before we have clear what we need the "thing" to be.


-M

ps
Just to illustrate the kind of possible reasoning's:
For instance, do we really need explicit versioning in v1 (explicit versus implicit versioning using namespaces)? If we do, then
shouldn't it be "in RDF"? If we don't, then the "thing" is just the import, and at then point, once clear what import we need, it
might end that we can just use XInclude, as Raphael nicely showed, and therefore don't get trapped in the issue at all :)
Received on Tuesday, 24 September 2002 11:35:40 GMT

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