- From: Philip Jägenstedt <philipj@opera.com>
- Date: Mon, 18 Jan 2010 22:41:39 +0100
- To: "Toby Inkster" <tai@g5n.co.uk>
- Cc: "Graham Klyne" <GK@ninebynine.org>, "Shelley Powers" <shelley.just@gmail.com>, "HTMLWG WG" <public-html@w3.org>
On Sun, 17 Jan 2010 20:47:29 +0100, Toby Inkster <tai@g5n.co.uk> wrote: > Cyclical references amongst blank nodes cannot be represented in > Microdata. In Turtle an example might be: > > @prefix foaf: <http://xmlns.com/foaf/0.1/> . > _:bob foaf:knows _:jon . > _:jon foaf:knows _:bob . > > In RDFa it can be expressed quite simply: > > <p xmlns:knows="http://xmlns.com/foaf/0.1/knows" > about="_:jon" rel="knows:" rev="knows:" resource="_:bob"> > Jon and Bob know each other. > </p> > > To express the same semantics in Microdata would require assigning a URI > to at least one of the people. Certainly it's possible for a script to > assign a URI on the fly, but committing to maintaining the meaning of > that URI long-term is harder, which is why blank nodes are so frequently > used in RDF. > > I believe, this could be addressed by allowing @itemid to contain a > blank node name, and providing a way for @itemprop to specify a blank > node as its value. Right, if there's an actual need then it's easy to hardwire the _:foo syntax to create blank nodes in the RDF extraction algorithm. Currently the algorithm ignores item types which aren't absolute URIs. Is _:foo an absoute URI, or is it not a URI at all? -- Philip Jägenstedt Core Developer Opera Software
Received on Monday, 18 January 2010 21:41:47 UTC