- From: Ivan Herman <ivan@w3.org>
- Date: Thu, 26 Jul 2007 11:09:58 +0200
- To: Niklas Lindström <lindstream@gmail.com>
- Cc: Ben Adida <ben@adida.net>, RDFa <public-rdf-in-xhtml-tf@w3.org>
- Message-ID: <46A864E6.2060600@w3.org>
Niklas Lindström wrote: > > == Striping == > > A. I want to interpret the rules given > (<http://lists.w3.org/Archives/Public/public-rdf-in-xhtml-tf/2007Jul/0158.html>) > > to determine subject for nested content (i.e. corresponding RDF > identity) in a generalised way as: > > - If a relation (with @rel) to a resource is given, that object is > used as subject for nested content. > - If that object is not explicit, a bnode is generated and used. > - Unless the above, use the subject given in the element (by > @about, perhaps by @id - see [C] below). > - If nothing of this applies, keep the current (inherited) subject. > > Does this make sense? > At first reading it does to me except for @instanceof (see below)... and I think it is in line with Ben's rules. > B. Furthermore, I'm uncertain about what the resulting state should be > when @rev is used? Consider: > > <div about="#something" rev="dct:hasPart" resource=""> > > which AFAIK yields: > > <> dct:hasPart <#something> . > > But what will the subject be for nested content? <#something> or <>? > Compare with this: > I think Ben's rules are clear on that: subject of nested content will be <>: [[[ the subject of an element's *content* is the element's corresponding RDF identity when @rel, @rev, @href, @resource, or @instanceof appears. Otherwise, it's @about resolution. ]]] And the RDF Identity is the value of @resource. > <div rel="dct:hasPart" resource="something"> > > yielding the same triple as above, and according to the rules clearly > having <#something> as the "nested subject". This becomes even > trickier for me if both @rel and @rev is present, or if @resource is > absent. > I do not really see a problem on the algorithmic level. @rel or @rev do not affect that choice of the RDF Identity... On a user level... well, I always considered @rev as a probably necessary thing but which is/should be used in somewhat exceptional circumstances anyway... > C. Finally (perhaps digressing). If @id is to be used at all, I wonder > if @about should not have precedence over this (as opposed to the > proposed order of the rules referred to above). This to enable > explicit prevention of non-semantic @id:s to have significance. Still, > I suppose this is the subject for another discussion. > > > == The rdf:type shorthand == > > D. Regarding rdf:type, will this shorthand be a syntactic one based > upon the (above) subject striping rules? As opposed to another > resolution technique possibly directly affecting the striping > algorithm? > > Assuming the former, is the rdf:type attribute (say @instanceof) a > plain shorthand for a child element with @rel="rdf:type" and a > @href/@resource? This must probably be the case, since if it is a > shorthand for putting the @rel etc in the same element, that would > make, by following the current idea of striping, the *type* the nested > subject. > Again, I think Ben's rules are clear on that: [[[ the element's corresponding RDF identity is the subject of an rdf:type triple when instanceof appears. ]]] ie, it is _not_ a purely syntactic sugar, but has its own rule of usage. And I have the impression that this fits pretty well our different use cases... Anybody is of course allowed to use a rel="rdf:type" and fall back on the general mechanism (if wished). > Though, if @instanceof is a shorthand for a nested element doing the > typing, its presence would not make the element where it appears mean > anything for RDFa itself, e.g. generate any bnode (or eventual special > @id treatment), which *may* be desired.. > > That would also make @instanceof appearing alone strange (typing an > ancestor?). Because of this, perhaps a condition for the rdf:type > shorthand should be that a "corresponding RDF identity" resolution > must occur for the same element it appears in (otherwise either > yielding nothing or even be an error). > > Or else it speaks for the latter case - a special rule both depending > on and affecting striping. > > E. Finally, for future thought, does it seem reasonable that when this > attribute appears at the root element of a document (or even head in > XHTML), its xml:base (explicit or implicit) will be the subject of the > rdf:type statement? I suppose so (and that this works for either case > here). Hm, that is interesting, but regardless of @xml:base. <html instanceof="foo:bar"> would mean, according to Ben's rule that a blank node is created: _:bb rdf:type foo:bar and, from then on, _all_ RDFa statements are relevant to _:bb, ie, this sets the new context. Unless explicitly referred to, <> will never be valid. I am not sure that is bad, but just shows a side-effect of our rules. But I do not see how @xml:base would have an influence on anything... Ivan > > > I sincerely hope these questions can be of relevance. > > Best regards, > Niklas > > > > > On 7/23/07, Ben Adida <ben@adida.net> wrote: >> >> >> Hi all, >> >> I suspect we're all hitting a little bit of spec fatigue. That said, we >> need to push through! We have one relatively important issue to cover >> (how striping really works), and a handful of smaller issues. >> >> So, *everyone* should take an action to think about and contribute >> thoughts on this list to the following issues, some time before Thursday. >> >> 1) Striping. @rel everywhere is hugely useful, but it does complicate >> things. Mark's latest description of what we should do: >> >> http://lists.w3.org/Archives/Public/public-rdf-in-xhtml-tf/2007Jul/0145.html >> >> >> and my proposed tweak with complete rules: >> >> http://lists.w3.org/Archives/Public/public-rdf-in-xhtml-tf/2007Jul/0158.html >> >> >> >> 2) the attribute name we should pick for rdf:type. It seems the only two >> real contenders so far are @instanceof, and @kind. I recently proposed >> @resourcetype, though haven't heard any feedback. >> >> Time to submit last suggestions including your top preference! >> >> >> 3) RDF containers and collections >> >> Last proposal and discussion: >> http://lists.w3.org/Archives/Public/public-rdf-in-xhtml-tf/2007Jul/0122.html >> >> http://lists.w3.org/Archives/Public/public-rdf-in-xhtml-tf/2007Jul/0131.html >> >> http://lists.w3.org/Archives/Public/public-rdf-in-xhtml-tf/2007Jul/0139.html >> >> >> >> 4) xml:lang >> >> We mentioned some solutions to this in the default datatype issue: >> >> http://lists.w3.org/Archives/Public/public-rdf-in-xhtml-tf/2007Jun/0039 >> >> are we okay with the conclusion of this with respect to xml:lang? >> >> >> 5) The @src attribute on IMG. I think this one is pretty much done, but >> we need to resolve it: >> >> <img about="#me" rel="foaf:image" src="ben.jpg" >> instanceof="foaf:Image" /> >> >> yields >> >> <#me> foaf:image <ben.jpg> . >> <ben.jpg> rdf:type foaf:Image . >> >> Any remaining issues on this for XHTML1.1+RDFa? I don't think so, but >> speak up if you do! >> >> >> >> -Ben >> >> > -- 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 Thursday, 26 July 2007 09:09:58 UTC