- From: Ian Davis <iand@internetalchemy.org>
- Date: Wed, 14 Jun 2006 09:41:08 +0100
- To: public-rdf-in-xhtml-tf@w3.org
I'd like to highlight a likely problem with RDFa's use of qname-like constructs in attribute values. I'm referring to CURIEs here but the same applies to any binding between XML namespace declarations and text content in the XML. The problem lies with the coupling of the specific prefix used in the namespace declaration with the prefix used in content. Any XML processor, such as an XSLT stylesheet or a SAX pipeline, can change the namespaces prefix arbitrarily thereby breaking the syntactic link between the qname/CURIE used in the attribute and the namespace declaration. The breakage happens because the XML processor has no knowledge of the semantics of particular text content in specific attributes. So, passing the following through a stylesheet: <p class="contactinfo" about="http://example.org/staff/jo" xmlns:contact="http://www.w3.org/2001/vcard-rdf/3.0#"> My name is <meta property="contact:fn"> Jo Smith </meta>. </p> could very easily result in the following, with the consequent loss of all embedded triples: <p class="contactinfo" about="http://example.org/staff/jo" xmlns:xyz="http://www.w3.org/2001/vcard-rdf/3.0#"> My name is <meta property="contact:fn"> Jo Smith </meta>. </p> As far as I can tell the only solutions are: 1) replace use of CURIEs in content with namespaced elements/attributes 2) replace namespace declaration mechanism with declarations based in the actual content with semantics specified by RDFa 3) replace CURIEs in content with full URIs 4) change XML namespaces spec to somehow understand CURIEs/qnames in content I think 1 is unlikely given that we're working within the limits of DTD and XSD validation 2 is the approach used by eRDF 3 would work for copy and paste at the expense of looking ugly, but I don't believe visual impact is a requirement of RDFa? 4 seems difficult and would introduce yet another dependency for RDFa adoption Ian -- http://purl.org/NET/iand Blogging at... http://iandavis.com/blog Working on... http://directory.talis.com/
Received on Wednesday, 14 June 2006 09:08:07 UTC