- From: Dan Connolly <connolly@w3.org>
- Date: Fri, 25 Aug 2006 14:13:29 -0500
- To: Chimezie Ogbuji <ogbujic@bio.ri.ccf.org>
- Cc: public-grddl-wg <public-grddl-wg@w3.org>
On Fri, 2006-08-25 at 00:01 -0400, Chimezie Ogbuji wrote: > Just some thoughts on the GRDDL mechanism WRT to POX: > > The only mechanism (currently) [1] outlined for a GRDDL client to follow > with an XML document is by grddl:transformation on the root > element or by dereferencing the URI associated with the > namespace of the document (root) element. The term namespace document is > used but it's not clear how this 'document' is resolved from the URI Why the scare quotes? The spec says explicitly how to dereference URIs, even though I would have thought it would go without saying... "The value of the grddl:transformation attribute designates a list of algorithms by URI reference (c.f. section 4.4.1. URI references in [WEBARCH])." I suppose it's not completely clear that section 4.4.1 also applies to getting namespace documents; I could add another [WEBARCH] reference to ... "if * the root element of an XML document ?XD is associated with a namespace name ?NS, and * ?NS identifies a document whose meaning includes the RDF statement ..." > I don't see a reason why not to include a much older precedent [2] Whether that's really a precedent is debateable; it says it's not: "The use of XML processing instructions in this specification should not be taken as a precedent. The W3C does not anticipate recommending the use of processing instructions in any future specification." -- http://www.w3.org/TR/xml-stylesheet/ The stylesheet PI should have used elements/attributes, IMO. But legacy schema technologies (DTDs) and browser release schedules constrained the design. As to why not use it: because I don't want to implement attribute parsing above the XML parser layer. It's bad enough that XSLT doesn't have a standard library function for making an absolute URI out of a base and a relative URI and that I had to code that by hand. http://www.w3.org/2000/07/uri43/uri.xsl Also, I consider the <?xml-stylesheet ?> link to relate a document to a transformation of that document for display for a human. I guess the spec doesn't say that. If I had a purchase order or something, I'd expect to be able to use the <?xml-stylesheet ?> PI to tell user agents how to display it for people, and a grddl:transformation link to tell data agents how to get data out of it. > in how transforms are associated with XML documents - especially for POX (instead > of XHTML where the mechanisms are more specific). > > Dereferencing namespace documents over HTTP, determining transformation by > HTTP content-type, and using XHTML semantics of rel='transformation' & > head/@profile seem appropriate for XHTML, but shouldn't the fallback > options for POX be (in this order)?: > > - Respond to grddl:transformation attribute on root document, resolving transform by HTTP URL > - Respond to <?xml-stylesheet type='..' href='..' appropriately to resolve transformation (fail if not one of the *expected* transformation types) > - Resolve RDF from namespace URI and respond to namespaceTransformation assertions (in RDF) > - Resolve a (master/default) RDF document from a URI (which would this be?) for a set of 'default' namespaceTransformation assertions I don't understand the last one at all. Maybe you could elaborate by way of an example? Otherwise, I could live with that. But I won't actively support the <?xml-stylesheet?> PI; I'll expect other people to provide the relevant test cases and trial implementation experience. > [1] http://www.w3.org/2004/01/rdxh/spec#ns-bind > [2] http://www.w3.org/TR/xml-stylesheet/ -- Dan Connolly, W3C http://www.w3.org/People/Connolly/ D3C2 887B 0F92 6005 C541 0875 0F91 96DE 6E52 C29E
Received on Friday, 25 August 2006 19:14:10 UTC