[whatwg] Fuzzbot (Firefox RDFa semantics processor)
Calogero Alex Baldacchino
alex.baldacchino at email.it
Sat Jan 10 18:01:13 PST 2009
Manu Sporny ha scritto:
> Calogero Alex Baldacchino wrote:
>> That is, choosing a proper level of integration for RDF(a) support into
>> a web browser might divide success from failure. I don't know what's the
>> best possible level, but I guess the deepest may be the worst, thus
>> starting from an external support through out plugins, or scripts to be
>> embedded in a webbapp, and working on top of other feature might work
>> fine and lead to a better, native support by all vendors, yet limited to
>> an API for custom applications
> There seems to be a bit of confusion over what RDFa can and can't do as
> well as the current state of the art. We have created an RDFa Firefox
> plugin called Fuzzbot (for Windows, Linux and Mac OS X) that is a very
> rough demonstration of how an browser-based RDFa processor might
> operate. If you're new to RDFa, you can use it to edit and debug RDFa
> pages in order to get a better sense of how RDFa works.
The concern is about every kind of metadata with respect to their
possible uses; but, while it's been stated that Microforamts (for
instance) don't require any purticular support by UAs (thus they're
backward compatible), RDFa would be a completely new feature, thus html5
specification should say what UAs are espected to do with such new
Shall UAs just "accept" them and expose an API to extract triples, so
that a web application can build a query mechanism upon such an API?
This might work fine, and fulfill small-scale scenarios, such as
organization-wise data modelling and interchanging, as suggested by
Charls McCathieNevile; this can also be accomplished by an external plugin.
Shall UAs (browsers) also provide an interface to view bare triples (as
does Fuzzbot), as a kind of debugging tool? As above.
Shall UAs (browsers) also provide metadata-based features, such as a
query interface to look for content in a local history? This is a wider
scale application, and also a use case where problems may arise. From
this angle, metadata can't be assumed as reliable apriori (instead,
their reliability is uncertain), nor can users be deemed capable to
understand the problem and filter out wrong/misused/abused metadata (in
general). This is the scenario were spammy metadata may become an issue.
For instance, some code like,
<p property="foaf:name" content="Manu Sporny">We sell
would produce the following triples,
_:bnode0 rdf:type http://xmlns.com/foaf/0.1/Person
_:bnode0 foaf:homepage http://www.cheatingcarseller.com
_:bnode0 foaf:name Manu Sporny
(this is exactly what Fuzzbot outputs)
thus, a metadata-based search feature might output a link to a
"metadata-spammy" site when queried for "Manu Sporny". That is, cheating
a metadata-based bot by the mean of fake metadata can be very easy.
Metadata-based features, but this is true for most of xml-related
technologies (such as RDF/RDFa), work fine if properly used. Unluckily,
"things must be used properly to work fine" is not the basic principle
of the web (and this is specially true for html and related
technologies), which instead has always been about "people will mess
everything up, but UAs will work fine as well", that is "robustness
before all, as far as possible". For what concerns html serialization,
in particular, I'd consider some code like,
one last summer Barbecue
<!-- /span -->, to meet friends and have a party before the end of
<span property="cal:dtstart" content="2007-09-16T16:00:00-05:00"
September 16th at 4pm
(taken from <http://www.w3.org/TR/2008/REC-rdfa-syntax-20081014/> and
which is rendered properly, but produces,
_:bnode1 rdf:type http://www.w3.org/2002/12/cal/icaltzd#Vevent
_:bnode1 cal:dtstart 2007-09-16T16:00:00-05:00
_:bnode1 cal:summary one last summer Barbecue , to meet friends
and have a party before the end of holidays on <span
16th at 4pm</span>
(taken from Fuzzbot keeping namespace declarations in the root element;
without xmlns:* attributes all triples are lost)
which is not the desired result. Perhaps it might work better as an xml
feature on a "strict" xml parser (aborting with an error because of a
missing end tag), even considering RDFa relies on namespaces (thus,
adding RDFa attributes to HTML5 spec would require some features from
xml extensibility to be added to html serialization). But RDFa in an
XHTML document might look like "rdfa:about", "rdfa:property",
"rdfa:content", and so on, that is as an external module, thus not
requiring any changes to the spec.
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