[whatwg] Trying to work out the problems solved by RDFa

Calogero Alex Baldacchino alex.baldacchino at email.it
Fri Jan 9 13:56:21 PST 2009

Ben Adida ha scritto:
> Tab Atkins Jr. wrote:
>> Actually, SearchMonkey is an excellent use case, and provides a
>> problem statement.
> I'm surprised, but very happily so, that you agree.
> My confusion stems from the fact that Ian clearly mentioned SearchMonkey
> in his email a few days ago, then proceeded to say it wasn't a good use
> case.
> -Ben

It seems to me that's a very custom use case - though requiring metadata 
to be embedded in a big number of pages, but that's an optional 
requirement, because search results don't rely only on metadata -  since 
metadata are used as an optional source for informations by the server 
and don't require any collaboration by other kinds of UA (excluding, at 
most, some custom data services - whereas, for instance, a search engine 
using the mark element to highlight a keyword would require a client UA 
to understand and style it properly -- I expect it not to be working on 
IE6, for instance, because IEx browsers deal with unknown elements as if 
their content where misplaced). That is, Yahoo might develop his own 
data model and work fine with sites implementing it; perhaps RDF(a) was 
chosen because they might think RDF is a natural way to model data which 
are sparse in a web page (and re-mapping microformats on RDF might 
result in an easier implementation); anyway, in this case the only UA 
needing to understand RDFa, in this case, is SearchMonkey itself, thus a 
client browser might just drop RDFa attributes without breaking 
SearchMonkey functionalities -- at least, this is my first impression.

Furthermore, it's a very recent (yet potentially interesting) 
application, so why not to wait and see how it grows, if the opt-in 
mechanism will effectively prevent spam (e.g. spammers might model data 
basing on widely diffused vocabularies and data services, and find a way 
to make such data available in searches when users asks for additional 
infos, for instance through an ad within a page of an accomplice author, 
or exploiting some kind of errors in authors' selection of URLs to be 
crawled for metadata, or the alike), or just which model become the most 
used among RDFa, eRDF, Microformats, Atom embedding dataRSS and whatever 
else Yahoo might decide to support, before choosing to include one or 
the other into html5 specification (or to include each one because 
equally diffused)? Moreover, it seems that some xml processing is needed 
to create a custom data service, thus it might be natural to use xhtml 
(possibly along with namespaces and prefixed attributes) to provide 
metadata to such a data service, which might rely on an xml parser 
instead of implementing one from scratch (and html parser might not 
support namespaces for the purpose to expose them through DOM 
interfaces, as I understand html serialization) -- the use of prefixed 
RDFa attributes, or perhaps even unprefixed ones, within an 
xml-serialized document, shouldn't require a formalization in html5 
spec, as far as there is no strict requirement for UAs to support RDF 
processing - as it is for the purposes of SearchMonkey and its related 
data services.

WBR, Alex
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