[whatwg] Annotating structured data that HTML has no semantics for

Shelley Powers shelleyp at burningbird.net
Thu May 14 05:34:43 PDT 2009

Dan Brickley wrote:
> On 14/5/09 14:18, Shelley Powers wrote:
>> James Graham wrote:
>>> jgraham at opera.com wrote:
>>>> Quoting Philip Taylor <excors+whatwg at gmail.com>:
>>>>> On Sun, May 10, 2009 at 11:32 AM, Ian Hickson <ian at hixie.ch> wrote:
>>>>>> One of the more elaborate use cases I collected from the e-mails
>>>>>> sent in
>>>>>> over the past few months was the following:
>>>>>> USE CASE: Annotate structured data that HTML has no semantics 
>>>>>> for, and
>>>>>> which nobody has annotated before, and may never again, for private
>>>>>> use or
>>>>>> use in a small self-contained community.
>>>>>> [...]
>>>>>> To address this use case and its scenarios, I've added to HTML5 a
>>>>>> simple
>>>>>> syntax (three new attributes) based on RDFa.
>>>>> There's a quickly-hacked-together demo at
>>>>> http://philip.html5.org/demos/microdata/demo.html (works in at least
>>>>> Firefox and Opera), which attempts to show you the JSON serialisation
>>>>> of the embedded data, which might help in examining the proposal.
>>>> I have a *totally unfinished* demo that does something rather similar
>>>> at [1]. It is highly likely to break and/or give incorrect results**.
>>>> If you use it for anything important you are insane :)
>>> I have now added extremely preliminary RDF support with output as N3
>>> and RDF/XML courtesy of rdflib. It is certain to be buggy.
>> So much concern about generating RDF, makes one wonder why we didn't
>> just implement RDFa...
> Having HTML5-microdata -to- RDF parsers is pretty critical to having 
> test cases that help us all understand where RDFa-Classic and HTML5 
> diverge. I'm very happy to see this work being done and that there are 
> multiple implementations.
> As far as I can see, the main point of divergence is around URI 
> abbreviation mechanisms. But also HTML5 might not have a notion 
> equivalent to RDF/RDFa's bNodes construct. The sooner we have these 
> parsers the sooner we'll know for sure.
> Dan
Actually, I believe there are other differences, as others have pointed 



Some of the differences have resulted in more modifications to the 
underlying HTML5 spec, which is curious, because Ian has stated in 
comments that support for RDF is only a side interest and not the main 
purpose behind the microdata section.

With the statement that support for RDF isn't a particular goal of 
microdata, Dan, I think you're being optimistic about the good this 
effort will generate for RDFa. But, more power to you.


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