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

Shelley Powers shelleyp at burningbird.net
Thu May 14 13:30:41 PDT 2009

Maciej Stachowiak wrote:
> 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.

Now, that's the problem with all of this effort...winners and losers.

I don't support a spec because it gives me grins and giggles. I have 
certain tasks I want to do, and I look for what is the technology that 
has the most support in order to do them.

I've long been an adherent to RDF, which isn't really up for debate. 
Originally, I was an RDF/XML person, until the RDF-in-XHTML folks 
changed my mind.

What I see of RDFa is a specification that has been through a very long 
period of time, testing, commenting, being implemented by major players. 
I also have tools, right now, that I can use to process the RDFa, as 
well as support by two major search engine companies.

As Dan pointed out earlier, microdata seems to support most of RDF. 
Well, I know that RDFa does. It makes little sense to me to start from 
scratch when a mature specification with multi-vendor support already 

Especially when Drupal 7 rolls out with RDFa baked in. That's 1.7 
million sites supporting the spec. Then there's the new Google snippet 
thing -- who knows how many additional sites we'll now find supporting RDFa.

So, if I'm pushing for RDFa, it's not because I want to "win". It's 
because I have things I want to do now, and I would like to make sure 
have a reasonable chance of working a couple of years in the future. And 
yeah, once SVG is in HTML5, and RDFa can work with HTML5, maybe I 
wouldn't mind giving old HTML a try again. Lord knows I'd like to user 
ampersands again.

>> 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.
It can't, don't you see?

Microdata will only work in HTML5/XHTML5. XHTML 1.1 and yes, 2.0 will be 
around for years, decades. In addition, XHTML5 already supports RDFa.

Why you think something completely brand new, no vendor support, drummed 
up in a few hours or a day or so is more robust, and a better option 
than a mature spec in wide use, well frankly boggles my mind.

I am impressed with your belief in HTML5.

> 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 
> markup.

Not really. Can do this now with RDFa in XHTML. And I don't need any new 
DOM to do it.

The power of semantic markup isn't really seen until you take that 
markup data _outside_ the document. And merge that data with data from 
other documents. Google rich snippets. Yahoo searchmonkey. Heck, even an 
application that manages the data from different subsites of one domain.

> 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.

Outcompeted...wow, what a way to think of it. Sorry, but competition has 
no place in spec work.



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