- From: Ivan Herman <ivan@w3.org>
- Date: Mon, 18 Jun 2007 18:13:44 +0200
- To: Laurent LE MEUR <Laurent.LEMEUR@afp.com>
- CC: semantic-web@w3.org, iptc-news-architecture-dev@yahoogroups.com, Henry Thompson <ht@w3.org>, Michael Sperberg-McQueen <cmsmcq@w3.org>
- Message-ID: <4676AF38.7000402@w3.org>
Dear Laurent, (cc-ing to two of my colleagues, Michael Sperberg-McQueen and Henry Thompson, who were kind enough to help me out with the details...) There is a W3C Recommendation called xpointer framework[1] which specifies a general mechanism to add all kinds of things to a URI after the '#', so to say. That framework relies on a so called scheme registry that is set up at W3C[2]. The scheme registry refers to xpath1 as one of the registered schemes, namely for XPATH1.0 expressions (and xpath2 for XPATH2.0). Using this registry, the following _is_ a valid URI: http://a.b.c/d#xpath1(//*[@id='person1' or @id='person2']) Caveats: - http://a.b.c/d should have a text/xml or application/xml or application/...+xml media type for that to make sense - As Jacco also said in his reply, there is no guarantee that this URI will be properly handled by a third party (eg, a browser) unless, say, the browser implements this scheme - an XPATH expression may return a node _set_ and not only a node. I am not really sure what this means in terms of your application, and the usage of those URI-s in a Semantic Web settings, if that happens... - formally, we are still waiting RFC3023bis, which will officially bless the use of fragment identifiers for the XML media types in general, and registry entries of [2] in particular... Ie: there is something, but it is not without problems either! I hope this helps nevertheless... Ivan [1] http://www.w3.org/TR/xptr-framework/ [2] http://www.w3.org/2005/04/xpointer-schemes/ Laurent LE MEUR wrote: > During the development of the new generation of IPTC (International > Press Telecommunications Council), IPTC members decided to use XPath > expressions to point at internal node sets in an XML instance, in a way > similar to the XSLT template/@match feature. > > > > We especially use this for indicating a reference to the part(s) of the > content a metadata property is about, e.g. (I admit that this is a > complex case): > > > > <newsItem> > > <subject about=”//*[@id='person1' or @id='person2']” confidence=”80”> > > <name>Georges W. Bush</name> > > </subject> > > <subject about=”//*[@id='person1' or @id='person2']” confidence=”20”> > > <name>Georges Herbert Walker Bush</name> > > </subject> > > … > > <html><body><p>xxx xxx <span id=”person1”>President Bush</span> xx. Yyy > yy yy<span id=”person2”>the US President</span> yyy.</p></body></html> > > </newsItem> > > > > The use of XPath allows us to make assertions about several pieces of > text at once (an alternative would be to use id/idrefs relations, but > the problem explained below would be the same). > > > > Now our problem: we want to be able to transform such assertions to RDF > triples. The subject of the triple is a piece of text: can an XPath > expression be an acceptable identifier for an RDF subject (my take is > that it must be a URI, and an XPath expression is not a URI)? > > If not, what are the good triples we can get from such a structure? I > looked at Annotea to find guidelines, and found that the piece of text > (represented by an XPointer in Annotea) is the value of the context > property of a resource which is the annotation itself (see > http://www.w3.org/2001/Annotea/Plan/context/newcontext.html). Is it the > SemWeb definitive view on it? > > > > Laurent Le Meur > > AFP > > IPTC News Architecture WP chair > > > > > > > > > This e-mail, and any file transmitted with it, is confidential and > intended solely for the use of the individual or entity to whom it is > addressed. If you have received this email in error, please contact the > sender and delete the email from your system. If you are not the named > addressee you should not disseminate, distribute or copy this email. > > For more information on Agence France-Presse, please visit our web site > at http://www.afp.com > > > -- Ivan Herman, W3C Semantic Web Activity Lead URL: http://www.w3.org/People/Ivan/ PGP Key: http://www.cwi.nl/%7Eivan/AboutMe/pgpkey.html FOAF: http://www.ivan-herman.net/foaf.rdf
Received on Monday, 18 June 2007 16:13:46 UTC