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Common Metadata (was:RE: RDF in XHTML)

From: Danny Ayers <danny@panlanka.net>
Date: Fri, 20 Apr 2001 20:19:30 +0600
To: "Lee Jonas" <lee.jonas@cakehouse.co.uk>, "Murray Altheim" <altheim@eng.sun.com>
Cc: "RDFInterest" <www-rdf-interest@w3.org>, "Brian McBride" <bwm@hplb.hpl.hp.com>
I can't see how RDF could be practical without some mechanism for
inherited/shared metadata (you've got a 1000 documents with the same
author - do you need to specify this a 1000 times), but I'm thinking that
because this is so significant it must have been dealt with already -
seeAlso doesn't really seem adequate, I'm not sure of the history of
aboutEachPrefix, but surely there is already some mechanism in place? Lee's
xsl:include/import suggestion sounds possible. If this angle is well
covered, an idiot's guide is needed (for this idiot at least), otherwise I
think it could well be an issue.

Danny Ayers

<- -----Original Message-----
<- From: www-rdf-interest-request@w3.org
<- [mailto:www-rdf-interest-request@w3.org]On Behalf Of Lee Jonas
<- Sent: 20 April 2001 19:47
<- To: 'Danny Ayers'; Murray Altheim
<- Cc: RDFInterest
<- Subject: RE: RDF in XHTML
<- Danny Ayers [mailto:danny@panlanka.net] wrote:
<- ><- The RDF Schema spec hints at 'rdfs:seeAlso' for cascading purposes,
<- e.g.:
<- ><-
<- ><- <rdf:RDF ...(namespaces)...>
<- ><- 	<rdf:Description rdf:about="" rdfs:seeAlso="furtherinfo.rdf"/>
<- ><- </rdf:RDF>
<- >
<- >Looks viable - I wonder if there's anything more than hints
<- >this is rather important, probably well known (but I can't
<- think of it) -
<- >what is the best way to use inheritance of metadata between documents?
<- >How do I avoid adding the same author information to every one of the
<- >million pages I've written (with the aid of some monkeys)?
<- >
<- Well, this is an entirely different prospect, and one I think that the
<- 'rdf:aboutEachPrefix' predicate was intended to address.
<- However, AFAIK it
<- has a lot of opposition due to the fact that it is difficult to
<- implement in
<- practise, e.g.:
<- 1) Consider starting with a resource and trying to determine who
<- the author
<- was.  If this info is in a 'rdf:aboutEachPrefix' statement in
<- some other rdf
<- doc, not even referenced from the resource you are currently
<- processing, it
<- is nigh on impossible to determine.
<- 2) It relies upon the hierarchical location of resource representations -
<- the granularity of what these kinds of statements apply to is
<- too course -
<- i.e. all resources whose URIs 'startWith' a common substring. It
<- might have
<- been better to do something akin to what XPointer does for XML.
<- Suggestion:
<- IMHO rdf:seeAlso is equivalent to xsl:include semantics.  What
<- is lacking is
<- xsl:import semantics.  The latter might allow you to define a set of
<- statements that apply to their current doc, then 'importing'
<- that doc from
<- another would make those same statements apply to the doc doing the
<- importing.  Hence, importing a handful of rdf docs containing common
<- statements (e.g. author) from a million XHTML web pages would
<- save a lot of
<- typing!
<- This would solve both 1) and 2) above to some degree of
<- satisfaction - the
<- degree of satisfaction of 2) depends on how you structure your imported
<- docs.  Is this worthy of the issues list?
<- >
<- >
<- ><- >On another line, forget XHTML for a moment, how do we embed
<- metadata in
<- ><- >other XML markups?
<- ><-
<- ><- I thought this is what XML Namespaces are for!  Just embed your
<- elements,
<- ><- any processor that doesn't recognise the namespace (within its
<- ><- context) can
<- ><- ignore it.  Note that to validate such documents properly (and allow
<- such
<- ><- open mixing-and-matching of different 'XML mini-languages') will
<- ><- require XML
<- ><- Schema.
<- >
<- >Quite. (to avoid this going in circles, please ignore) so why
<- should XHTML
<- >be treated any different?
<- One reason is that it is currently validated using a DTD.  Whether XML
<- Schema would fare better, I don't altogether know for sure.
<- (Note that my current understanding of XML Schema is not perfect, I am
<- hoping that XML Schema allows you to freely mix-and-match elements in
<- different XML namespaces.)
<- regards
<- Lee
Received on Friday, 20 April 2001 10:24:10 UTC

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