- From: Ivan Herman <ivan@w3.org>
- Date: Sun, 04 Nov 2007 09:49:44 +0100
- To: "Hausenblas, Michael" <michael.hausenblas@joanneum.at>
- CC: Phil Archer <parcher@icra.org>, public-powderwg@w3.org, RDFa <public-rdf-in-xhtml-tf@w3.org>
- Message-ID: <472D87A8.8020700@w3.org>
:-) Ivan Hausenblas, Michael wrote: > Kudos to Ivan, who knew that I was on travel and unfortunately > not able to respond earlier. I myself could certainly not have > done it better ;) > > Cheers, > Michael > > ---------------------------------------------------------- > Michael Hausenblas, MSc. > Institute of Information Systems & Information Management > JOANNEUM RESEARCH Forschungsgesellschaft mbH > Steyrergasse 17, A-8010 Graz, AUSTRIA > ---------------------------------------------------------- > >> -----Original Message----- >> From: Ivan Herman [mailto:ivan@w3.org] >> Sent: Thursday, November 01, 2007 1:11 PM >> To: Phil Archer >> Cc: Hausenblas, Michael; public-powderwg@w3.org; RDFa >> Subject: Re: POWDER-related questions about RDFa linkage >> >> If you allow me to impersonate Michael for the moment:-) >> (which does not mean that he cannot answer!:-) >> >> Phil Archer wrote: >>> Michael, >>> >>> As you and others have been kind enough to look at the >> potential usage >>> of RDFa and POWDER, I'd like to ask a couple of questions please. >>> >>> I'd like to significantly improve what we say about RDFa, either in >>> the Rec Track Description Resources doc [1] or, if more >> appropriate, >>> in a non-normative POWDER Primer we'll be starting work on >> later this month. >>> Easier question first. Can I ask you for a sanity check on this >>> example >>> please: >>> >>> Example 1 >>> ========= >>> >>> <html >>> xmlns="http://www.w3.org/1999/xhtml" >>> xmlns:wdr="http://www.w3.org/2007/05/powder#" >>> <head> >>> <title>The English Civil War</title> >>> <link rel="wdr:describedBy" >>> href="http://education.example.org/powder.rdf#DR_1" /> >>> </head> >>> <body> >>> ... >>> <p>Charles I came to the throne believing in his Divine >> Right to >>> rule... >>> ... >>> </body> >>> </html> >> Although we do not have it in the current document yet, we >> will have an RDFa profile, too. It may not be mandatory to >> use it, but advised. Ie, you should probably add the >> >> <head profile="http://www.w3.org/ns/rdfa/"> >> .... >> >> Otherwise, this should be o.k.; it will generate the triple >> >> <URI-of-the-document> wdr:describedBy >> http://education.example.org/powder.rdf#DR_1. >> >>> That is, a single use of wdr:describedBy at document level. >> Actually, >>> for this kind of linkage from an HTML doc, the usual way will be to >>> use an HTML profile we're drafting and a relationship type >> of powder thus: >>> Example 2 >>> ========= >>> >>> <html xmlns="http://www.w3.org/1999/xhtml"> >>> <head profile="http://www.w3.org/2007/10/powder-profile"> >>> <link rel="powder" >>> href="http://education.example.org/powder.rdf#DR_1" /> >>> <title>The English Civil War</title> >>> </head> >>> <body> >>> <p>Charles I came to the throne believing in his >> Divine Right to >>> rule...</p> >>> </body> >>> </html> >>> >> Actually... this is still in flux. At the moment, the RDFa >> rule is that @rel values without a prefix will be ignored. We >> do not have (yet?) a general mechanism that would allow an >> RDFa processor to understand a profile in the head >> automatically and take those @rel values. Ie, it may be >> better to stick with the wdr: prefix. (As I said: this is >> still a bit in flux, the TF members may well chime in here!) >> >>> But I'm really hoping that RDFa can be used for more >> powerful things. >>> In particular, that we can use it to link to a Description Resource >>> that describes the target of a hyperlink as simply as >> possible. If I >>> understand RDFa correctly that means doing something like this: >>> >>> Example 3 >>> ========= >>> >>> <html >>> xmlns="http://www.w3.org/1999/xhtml" >>> xmlns:wdr="http://www.w3.org/2007/05/powder#" >>> <head> >>> <title>The English Civil War</title> >>> <link rel="wdr:describedBy" >>> href="http://education.example.org/powder.rdf#DR_1" /> >>> </head> >>> <body> >>> ... >>> <p>Charles I came to the throne believing in his >>> <link about="#divRight" rel="wdr:describedBy" >>> href="http://education.example.org/powder.rdf#DR_2"> >>> <a href="http://education.example.org/divine_right.html" >>> id="divRight">Divine Right</a> to rule... >>> ... >>> </body> >>> </html> >>> >> First of all: RDFa does not change the content model of >> XHTML1, ie, the <link> element is _not_ permitted in the body. >> >> >> <html >> xmlns="http://www.w3.org/1999/xhtml" >> xmlns:wdr="http://www.w3.org/2007/05/powder#" >> <head profile="http://www.w3.org/ns/rdfa/"> >> <title>The English Civil War</title> >> <link rel="wdr:describedBy" >> href="http://education.example.org/powder.rdf#DR_1" /> >> </head> >> <body> >> ... >> <p>Charls I came to the throne believing in his >> <a >> about="http://education.example.org/powder.rdf#DR_2" >> rev="wdr:describedBy" >> href="http://education.example.org/divine_right.html">Divine >> Right</a> to rule... >> >> ... >> </body> >> </html> >> >> The trick is the usage of @rev and not @rel; @rev, >> essentially reverts the roles for subject and object. I guess >> this is what you want, right? >> >> I hope this helps. >> >> Ivan >> >> >> >> >>> So we have a hyperlink in the document to one about divine >> right. That >>> second document is the subject of a triple thus: >>> >>> <http://education.example.org/divine_right.html> >>> wdr:describedBy >>> <http://education.example.org/powder.rdf#DR_2> >>> >>> is there a more terse way of creating this triple within >> the RDFa/XHTML? >>> I guess the problem is that would entail having two href >> attributes in >>> a single hyperlink, which is silly, but the use cases are >> pretty clear >>> for us. For example, imagine that the English Civil War document is >>> mobileOK and is being displayed on a mobile device - should >> my browser >>> display the hyperlink to the divine right document or not? If it's >>> mobileOK too (as declared in DR_2) then the answer's yes, >> if not, then >>> just show the text without the hyperlink. >>> >>> Finally, how far can we go in a Rec Track document that >> we're hoping >>> to declare as at Last Call after next week's face to face? >> Is Example >>> 1 sound? Is Example 3 sound? >>> >>> Thanks very much for your help, >>> >>> Phil. >>> >>> [1] http://www.w3.org/TR/2007/WD-powder-dr-20070925/#semlink >>> >> -- >> >> Ivan Herman, W3C Semantic Web Activity Lead >> Home: http://www.w3.org/People/Ivan/ >> PGP Key: http://www.ivan-herman.net/pgpkey.html >> FOAF: http://www.ivan-herman.net/foaf.rdf >> >> -- Ivan Herman, W3C Semantic Web Activity Lead Home: http://www.w3.org/People/Ivan/ PGP Key: http://www.ivan-herman.net/pgpkey.html FOAF: http://www.ivan-herman.net/foaf.rdf
Received on Sunday, 4 November 2007 08:49:59 UTC