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

[Shelley Powers]

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 
out.

http://www.jenitennison.com/blog/node/103

http://realtech.burningbird.net/semantic-web/semantic-web-issues-and-practices/holding-on-html5

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.

Shelley