Tab Atkins Jr. on Tue, 12 May 2009 12:30:27 -0500:
On Tue, May 12, 2009 at 5:55 AM, Eduard Pascual:
> [...] It would be preferable to be able
> to state something like "each (row) <tr> in the <table> describes an
> iguana: the <img>s are each iguana's picture, the contents of the
> <a>'s are the names, and the @href of the <a>'s are the URLs to their
> main pages" just once.
Indeed.
> If I only need to state the table headings once
> for the users to understand this concept, why should a micro-data
> consumer require me to state it 20 times, once for each row?
> Please note how such a page would be quite painful to maintain: any
> mistake in the micro-data mark-up would generate invalid data and
> require a manual harvest of the data on the page, thus killing the
> whole purpose of micro-data.
Indeed. (But of course, for "copy-paste" safety, the format has to be
"wordy" and repetitive.)
And repeating something 20 (or more)
> times brings a lot of chances to put a typo in, or to miss an
> attribute, or any minor but devastating mistake like these.
Well, he didn't quite *ignore* it - he did explicitly call out that
requirement to say that his solution didn't solve it at all. He also
laid down the reason why - it's unlikely that any reasonable simple
in-place metadata solution would allow you to do that. You either
need significant complexity, some reliance on language semantics (like
tables can rely on their headers), or moving to out-of-band
specification, likely through a Selectors-based model.
Indeed. And Ian's arguments against a selector based model (the claim
that authors have problems understanding selectors) was one of the least
convincing arguments he made, I think. CSS and selectors appears to be
one of the best understood technologies of the web.
The last is likely the best solution for that, and is even easier to
implement within Ian' simplified proposal. I don't see a good reason
why that can't advance on a separate track, as (being out-of-band) it
doesn't require changes to HTML to be usable.
I floated a basic proposal for Cascading RDF[1] several months ago,
and someone else (I think Eduard? I'd have to check my archives) did
something very similar.
[1]: http://www.xanthir.com/rdfa-vs-crdf.php
Hear hear. Lets call it "Cascading RDF Sheets". It could be used for
the following purposes:
1. The IRI of the Cascading RDF Sheet could serve the role of profile URI;
2. The Cascading RDF Sheet itself could serve the role of a profile
document; (Finally we could get some kind of registered profile format.)
3. Just as CSS sheets today, a cRDFsheet could be used as authoring
help, when authoring with a microformat. HTML editing programs could
offer the elements + classes in the Cascading RDF Sheet to authors, the
same way that some editors to today use the selectors in stylesheets as
a "vocabulary repository" for the current file or project. CSS selectors
is already a well known format. (One may then, of course, already use a
CSS style sheet for this, kind of. But this soon becomes clumsy. Better
to separate styling from semantics and structure.)
In fact, I myself begun looking into creating something along these
lines ... Though rather than a "Cascading RDF Sheet", I looked into
creating a "Profile Style Sheet" which could be used to define a machine
readable microformat profile. My motivation for doing this was the
authoring side of things, as I have been using a text editor which more
or less uses CSS selectors the same way. (Instead of only offering me to
pick "<p>" it also offers me to to pick <p class="a"> etc.) Ian's
proposal do not give much thought about the authoring side, I feel,
except for the more casual author. For authors, it is helpful to have a
"recipe" document and to avoid repetition and "data rot", as you
mentioned in another message.
Ian's microdata format is easy to grasp the inner logics of - that is a
good side of the proposal, this could help that it gets used. But when
it comes to author's and author groups' ability to define their own,
decentralised semantics etc., then a decent profile format, which could
be easily and simply integrated with authoring tools, seems like a just
as important issue as a super simple microdata format.
The microformats.org community does not really have a machine parsable
profile format. If there were such a format, I believe we would see more
of more decentralized microformats.
--
leif halvard silli
