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

Maciej Stachowiak mjs at apple.com
Thu May 14 13:17:32 PDT 2009

On May 14, 2009, at 1:04 PM, Shelley Powers wrote:

> Maciej Stachowiak wrote:
>> On May 14, 2009, at 5:18 AM, Shelley Powers wrote:
>>> So much concern about generating RDF, makes one wonder why we  
>>> didn't just implement RDFa...
>> If it's possible to produce RDF triples from microdata, and if RDF  
>> triples of interest can be expressed with microdata, why does it  
>> matter if the concrete syntax is the same as RDFa? Isn't the  
>> important thing about RDF the data model, not the surface syntax?
>> (I understand that if the microdata syntax offered no advantages  
>> over RDFa, then it would be a wasted effort to diverge. But my  
>> impression is that you'd object to anything that isn't exactly  
>> identical to RDFa, even if it can easily be used in the same way.)
>> Regards,
>> Maciej
> Because one would assume that one way to accomplish a task would be  
> more attractive to web developers, designers, parser developers,  
> browsers, et al.
> In addition, one would also assume that one way to accomplish a task  
> would be more attractive in regards to testing, maintaining and  
> moving on in the future.
> Notice how there is only VHS and not Betamax?
> Notice the same about Blu-Ray and HD-TV? People won't buy into  
> something while there are competitive specs, and these are  
> "competitive" in that it makes little since to use both in a  
> document, though you can now.

Physical media do tend to converge due to network effects. I think the  
effect is less strong for digital file formats. For example, MP3 and  
AAC are both fairly successful; similarly, MPEG-4, Windows Media and  
Ogg are all getting some degree of traction. But you may be right that  
ultimately there will be only one winner.

> The point is, people in the real world have to use this stuff. It  
> helps them if they have one, generally agreed on approach. As it is,  
> folks have to contend with both RDFa and microformats, but at least  
> we know these have different purposes.

 From my cursory study, I think microdata could subsume many of the  
use cases of both microformats and RDFa. It seems to me that it avoids  
much of what microformats advocates find objectionable, and provides a  
good basis for new microformats; but at the same time it seems it can  
represent a full RDF data model. Thus, I think we have the potential  
to get one solution that works for everyone.

I'm not 100% sure microdata can really achieve this, but I think  
making the attempt is a positive step.

One other detail that it seems not many people have picked up on yet  
is that microdata proposes a DOM API to extract microdata-based info  
from a live document on the client side. In my opinion this is huge  
and has the potential to greatly increase author interest in semantic  

Now, it may be that microdata will ultimately fail, either because it  
is outcompeted by RDFa, or because not enough people care about  
semantic markup, or whatever. But at least for now, I don't see a  
reason to strangle it in the cradle.


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