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LANG: owl:imports straw man

From: Smith, Michael K <michael.smith@eds.com>
Date: Fri, 20 Sep 2002 13:56:09 -0500
Message-ID: <B8E84F4D9F65D411803500508BE3221410A2A9C8@USPLM207>
To: Webont <www-webont-wg@w3.org>

I just thought I would put forth a straw man importing solution 
that is the most trivial I can imagine.  It is in the class of
solutions that do not make the ontology name and its relationships
part of the ontology.

- Mike

Consider a purely syntactic #INCLUDE-like mechanism, out of the scope
of any enclosing OWL/RDF.  Owl:include doesn't mean anything,
formally.  Its a pre-processing directive.  We do need to deal with
loops, which languages like C punt on.

<owl:include import="uri1" />

<rdf:rdf ...> 
 ...
</rdf:rdf>

Let UriSet be the transitive closure of the imported uri's in the document.

For all urin in UriSet,
 Insert the rdf:rdf elements of those uri's, 
  modified by the addition of an xml:base="urin" attribute/value
  to the rdf:rdf tag.

E.g., for each urin add

<rdf:rdf xml:base="urin" ... >
 ... 
</rdf:rdf>

There is no restriction on RDF that says there can only be a single
rdf:rdf element in a document, so this would seem to work.  It does
mean that we need to import ALL rdf:rdf elements contained in the
target uri.

If you want your RDF processor to work with this mechanism you would
need to modify it to honor the imports and handle xml:base.
But as far as I can see, any solution to imports
is going to require some mods to your RDF processor, except perhaps if
we go with XInclude.  (Recent messages suggest even that is
optimistic.)  Which is the main attraction of XInclude, but I am
concerned that that standard is too restrictive.

If we are willing to accept the no-cycles restriction of XInclude
then we could probably use it.  Particularly in this simple case where
we are assuming it is not imbedded within RDF.

I confess to having trouble making sense of the differences between
inclusion restrictions and loops in the XInclude standard when
'parse="xml"' vs 'parse="text"'.  It looks like the text case is not
recursive with respect to XInclude and the xml case considers loops
and ill-formed XML a fatal error.
Received on Friday, 20 September 2002 14:58:21 GMT

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