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Re: Minutes for July 30th, 2009 RDFa Telecon

From: Martin McEvoy <martin@weborganics.co.uk>
Date: Wed, 05 Aug 2009 15:52:38 +0100
Message-ID: <4A799CB6.6090007@weborganics.co.uk>
To: Philip Taylor <pjt47@cam.ac.uk>
CC: Manu Sporny <msporny@digitalbazaar.com>, RDFa Developers <public-rdf-in-xhtml-tf@w3.org>
Hello Philip,

Philip Taylor wrote:
> Martin McEvoy wrote:
>> ...
>> Is there anything wrong with using xmlns: in the way I have proposed 
>> above?  as I am unsure of what the Issues may be?, I think structure 
>> an content are more clearly defined....? also xmlns is not 
>> depreciated in html5 so really what's the cost?
> HTML 5 (in its text/html serialisation) currently doesn't allow xmlns: 
> to be used in that way. The only thing it allows is 
> xmlns="http://www.w3.org/1999/xhtml" on an HTML element, and a few 
> special cases in inline MathML/SVG content. Anything else is invalid.

What happens to the invalid attributes?, are they simply marked as 
garbage and then removed from the DOM?, also do you not also think that 
RDFa is a "special case" ?

> It's unlikely that HTML 5 would allow xmlns: (or any other attribute 
> name containing a colon) in valid documents, because it would either 
> encourage violation of the "DOM Consistency" principle 
> (http://www.w3.org/TR/html-design-principles/) or would risk violating 
> "Support Existing Content". 

There is something right at the top of that page, before It even talks 
about the DOM about paving the cowpaths...

"2.4. Pave the Cowpaths

When a practice is already widespread among authors, consider adopting 
it rather than forbidding it or inventing something new.

Authors already use the <br/> syntax as opposed to <br> in HTML and 
there is no harm done by allowing that to be used. "

Inventing something new in HTML 5 I would say is microdata why use it If 
RDFa already exists?

It goes on in the next section which is relative to this issue....

"2.5. Evolution Not Revolution

Revolutions sometimes change the world to the better. Most often, 
however, it is better to evolve an existing design rather than throwing 
it away. This way, authors don't have to learn new models and content 
will live longer. Specifically, this means that one should prefer to 
design features so that old content can take advantage of new features 
without having to make unrelated changes. And implementations should be 
able to add new features to existing code, rather than having to develop 
whole separate modes. ".

Sorry for quoting that at you, but since you brought it up.....

It leads me now to believe that using xmlns: is ok anyway, and really 
HTML5 should try to adapt an existing way that works rather than 
inventing something new or ignoring RDFa altogether.

Best wishes

Martin McEvoy
Received on Wednesday, 5 August 2009 14:53:31 UTC

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