- From: Smith, Michael K <michael.smith@eds.com>
- Date: Wed, 14 Aug 2002 15:04:44 -0500
- To: Jonathan Borden <jonathan@openhealth.org>, Jos De_Roo <jos.deroo.jd@belgium.agfa.com>
- Cc: "Smith, Michael K" <michael.smith@eds.com>, www-webont-wg@w3.org
I still have one confusion. The XML Namespace document (http://www.w3.org/TR/REC-xml-names/) states: URI references which identify namespaces are considered identical when they are exactly the same character-for-character. Note that URI references which are not identical in this sense may in fact be functionally equivalent. In general, when I want a prefix like 'xsd' to refer to datatypes defined by the XML Schema definition, I include something like xmlns:xsd="http://www.w3.org/2001/XMLSchema" But, the RDF and DAML+OIL documents use xmlns:xsd="http://www.w3.org/2001/XMLSchema#" According to the opening quote these may be functionally identical, but they certainly are not identical by default. So, where is this equivalence asserted? Or is it just common knowledge? - Mike -----Original Message----- From: Jonathan Borden [mailto:jonathan@openhealth.org] Sent: Wednesday, August 14, 2002 12:13 PM To: Jos De_Roo Cc: Smith, Michael K; www-webont-wg@w3.org Subject: Re: GUIDE: Dumb question re namespaces. Jos De_Roo wrote: > > > Why are all of the RDF and DAML example namespace URIs suffixed with a > '#'? > > well, not *all* of them... > it was agendum 8 for RDF Core Teleconference 2002-08-09 (datatypes, # | /) > http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2002Aug/0090.html > but it wasn't discussed at that telecon > Sigh, there are two answers: 1) from a practical point of view, when RDF converts an XML Qname to a URI, the namespace URI and local name are merely appended to form a URI reference. If an alphanumeric character is at the end of a namespace URI, it will be unclear in the resulting (concatenated) URI which part was from the namespace URI and which part was from the local-name, making it impossible to recover the QName from the URI reference. This is the essential problem with non-RDF QNames such as those that identify XML Schema types e.g. <foo:example rdf:about="http://example.org" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <xsd:string>an XML Schema string</xsd:string> </foo:example> which parses according to RDF into: <http://example.org> <http://www.w3.org/2001/XMLSchemastring> "10" . as opposed to (the intended) ... <http://www.w3.org/2001/XMLSchema#string> "10" . 2) TimBL suggests that HTTP URIs ought only identify _documents_ whereas such URIs _with_ a '#' can identify anything (see www-tag@w3.org for details). Hence XML Namespaces, being abstract entities rather than documents, ought have a '#'. This view is, however, controversial. Jonathan
Received on Wednesday, 14 August 2002 16:04:56 UTC