- From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
- Date: Sun, 21 Oct 2001 21:41:20 -0400
- To: bwm@hplb.hpl.hp.com
- Cc: www-rdf-interest@w3.org, simeon@research.bell-labs.com
From: Brian McBride <bwm@hplb.hpl.hp.com> Subject: Re: a new way of thinking about RDF and RDF Schema Date: Sun, 21 Oct 2001 23:24:38 +0100 > Peter F. Patel-Schneider wrote: > > [...] > > >>> > >>Most RDF parsers are built on a standard XML parser. This is true of SiRPAC, > >>RDFFilter, ARP and Redland's parser. > > > > How can this be? RDF is not XML. > > RDF/XML (to name the xml syntax for RDF, not the RDF datamodel) is a subset of > XML. It conforms to XML syntax. Parsers deal with syntax. RDF/XML is not a subset of XML. parseType=literal is in M&S. It has been in from the beginning. parseType=literal requires that its context not be processed by an XML parser. parseType=literal elicits the most puzzlement from XML people that I try to explain RDF to, even ignoring the current debate over its details. > > How do they handle parseType? An RDF > > system that handles parseType has to get its hands on the raw bits, before > > an XML parser sees them. > > That statement is not correct. RDF parsers such as RDFFilter, ARP and SiRPAC > are built on top of an XML parser. > > Typically they operate in streaming mode, where the XML parser outputs a stream > of SAX events which are interpreted by the RDF parser. Then how can they handle parseType=literal? I really don't understand how. > parseType="Literal" is something the RDFCore WG is, err ..., working on, right > now. Its not really clear exactly how to handle this. Most parsers currently > turn it into a Literal, but there is no agreement on exactly what Literal. > Other suggestions include generating an RDF representation of the infoset > representation of the embedded xml. Yes, but how? Once XML parsing is done you no longer have the original bits to be turned into a literal. > But whatever the outcome of that discussion, I'd expect RDF parsers to continue > to be built on XML parsers. Am I missing something? I just don't see how there is any way that parsetype=literal can be done after XML processing. > >>><rdf:Description rdf:type="a:b"/> is not valid RDF because a:b is not a > >>>literal, not (just) because QNames are not allowed as attrib values. > >>> > >>This is a nit, but the rdf:type attribute is a special case in RDF. The value > >>of the attribute is the URI of a resource, not a literal. You may wish to add > >>that to your list of mistakes in RDF. > >> > > > > Precisely. Therefore RDF can't use the abbreviation you wanted. > > You might like to have a look at the following para in M&S > > http://lists.w3.org/Archives/Public/www-archive/2001Jun/att-0021/00-part#227 You are correct. Yet another special case in the syntax. > Brian Peter F. Patel-Schneider
Received on Sunday, 21 October 2001 21:42:07 UTC