- From: Lin Clark <lin.w.clark@gmail.com>
- Date: Tue, 6 Sep 2011 12:23:48 +0100
- To: Ivan Herman <ivan@w3.org>
- Cc: Jeni Tennison <jeni@jenitennison.com>, public-rdfa-wg WG <public-rdfa-wg@w3.org>
- Message-ID: <CACho_AtsCGfT9dzjnOvDLXif-YGbPrM6x2-_nS7RggHo2xshGQ@mail.gmail.com>
Actually, it wasn't multiple references to the same object that we need itemref for in the microdata implementation. It was that there are often properties that are outside of the entity's branch of the DOM tree, so the only options are to include an invisible meta element for each value, duplicating the values, or to use itemref. Itemref should be better for front end performance because it results in fewer characters for most use cases, so that's why Drupal would need it. While the ability of an itemref-ed item to be referenced from multiple elements could come in handy, it isn't a use case I had explored yet. At first glance, having multiple abouts would seem to make RDFa harder to grok, but I haven't really thought deeply about it. -Lin On Tue, Sep 6, 2011 at 8:18 AM, Ivan Herman <ivan@w3.org> wrote: > Jeni, > > I will play today (or tomorrow) with the implementation of this to see if > there are unexpected hiccups. I do not expect any, but one may never know. > > One thing: I wonder, if @about can accept a list of URI-s, whether so > should @resource. After all, by virtue of chaining, @resource plays a > similar role to @about down the line... Implementation wise this is probably > the natural way: the overall change on the processing steps is, I guess, > that the values of current object, subject, etc, become all arrays instead > of single values, providing a natural set of changes on the steps. So the > question is whether, from the user's point of view, we should open up > @resource to be an array or not. I must admit I am a bit neutral at this > point. The 'why not?' is probably not a good enough argument:-) > > (Obviously, this change would not affect @href, whose syntax and semantics > we inherit from HTML.) > > Lin, it would be terrific to get your feedback on whether that type of > change would make Drupal's life easier... > > Thanks > > Ivan > > On Sep 6, 2011, at 24:00 , Jeni Tennison wrote: > > > Gregg (etc) > > > > On 3 Sep 2011, at 00:13, Gregg Kellogg wrote: > >> As @itemref is not universally appreciated, and causes a many issues for > SAX-based implementations, we discussed possible alternatives. For example, > if @about where to take a list of IRIs, rather than just a single IRI, you > might have the following: > >> > >> <body vocab="http://schema.org/"> > >> <div about="_:m" typeof="schema:Movie"> > >> <p property="schema:name">Pirates of the Carribean: On Stranger Tides > (2011)</p> > >> </div> > >> <div about="_:b typeof="schema:Book"> > >> <span property="schema:name">How to Tie a Reef Knot</span> > >> by <span property="author">John Doe</span> > >> </div> > >> <footer about="_:m _:b"> > >> <p>All content licensed under the > >> <a rel="license" href=" > http://www.opensource.org/licenses/mit-license.php"> > >> MIT license > >> </a>. > >> </p> > >> </footer> > >> </body> > > > > I agree that the multi-valued about attribute is a way of addressing most > of the use cases that led to itemref in microdata which fits quite naturally > with RDFa's existing processing. > > > > FWIW, the one thing that I'd point out as a disadvantage to this approach > for a publisher is that it means that when the common content (the > information about the license of the page) is generated, the code needs to > have knowledge of the content of the page. > > > > So the above couldn't be generated by a footer generated by a static > template, for example. Conversely, if the pointers go the other way -- items > in the body of the page referencing common things in the static content, as > in itemref -- that's a lot easier to generate. > > > > I've CCed Lin because she'd mentioned the use of itemref within Drupal, > and it would be good to have her thoughts on whether this pattern might work > based on that experience. > > > > Cheers, > > > > Jeni > > -- > > Jeni Tennison > > http://www.jenitennison.com > > > > > > > ---- > Ivan Herman, W3C Semantic Web Activity Lead > Home: http://www.w3.org/People/Ivan/ > mobile: +31-641044153 > PGP Key: http://www.ivan-herman.net/pgpkey.html > FOAF: http://www.ivan-herman.net/foaf.rdf > > > > > > -- Lin Clark DERI, NUI Galway <http://www.deri.ie/> lin-clark.com twitter.com/linclark
Received on Tuesday, 6 September 2011 11:24:27 UTC