Re: A Response to Comments

* Ben Adida wrote:
>A while ago (18 months or so) [1], you sent an email with concerns
>regarding RDFa (previously written RDF/A). Though there have been some
>responses to your concerns in the past [2], we thought it would be
>useful to completely review the issues you brought up now that the XHTML
>and RDFa documents are maturing.

To re-establish the context of my mail: back in November 2004 the W3C
Semantic Web Best Practices and Deployment Working Group asked the HTML
Working Group to adopt RDF/A in XHTML 2; in response to that I asked the
group to do the opposite and, instead, come up with adequate meta data
facilities that meet the needs of the HTML authoring community.

I then analyzed how the design requirements cited in the then current
RDF/A draft are irrelevant and/or haven't been met by the design, and
that important requirements have been ignored entirely. I will discuss
these points in more detail below. The HTML Working Group's response to
my request was:

  Thanks for your comment. While we value your input, at this time
  we are not able to agree with your request. The RDF/A activity has
  substantial support and discussion in the community, and supporting
  embedded meta information in a consistent, intuitive, and relatively
  easy manner is a major requirement for XHTML 2.

I have yet to see evidence of substantial support; so far I only saw the
exact opposite. As an example, Tantek Çelik wrote in [1]:

  You might even say that the insanity of the ugliness of RDF/A was one
  of inspirations for a lot of simplicity and human-centric aspects of
  microformats.

and Ian Hickson writes in [2]:

  RDF/A is an utter disaster and not a valid use case for anything.

Contrary to what you say, little if anything has been done to address
the concerns raised by Tantek, Ian, reviewers on www-html, or myself.

  [1] http://microformats.org/discuss/mail/microformats-discuss/2006-May/004144.html
  [2] http://lists.whatwg.org/pipermail/whatwg-whatwg.org/2006-July/006892.html

>The point is that there is no W3C technology that allows XHTML with
>RDF/XML to be validated. Although XHTML Modularization includes
>techniques to make fixed modules of elements from other namespaces
>validatable with DTDs, the statement you quote indicates the
>completeness of the problem: there is not a single way to include
>RDF/XML inside XHTML1, not via XML schema, not via DTDs.

That is neither the point cited in the design document, nor is it true.
The design document in fact points out that Relax NG addresses the val-
idation requirements, and as e.g. SVG Tiny 1.2 relies exclusively on
NVDL and Relax NG for the purposes of schema validation, the argument
that these technologies lack support no longer applies. So as I pointed
out, the requirement is irrelevant and should not have informed the de-
sign of RDF/A.

>You can still use <cite> in XHTML2. Thus, if you don't care about RDF
>and want to style a <cite>, you can use the same XHTML and CSS as before.

The design document argues that "hard-wired" attributes like the cite=''
attribute are bad design, and instead child elements with externally de-
fined properties should be used. I pointed out the many problems with
this approach, which essentially imply that in many cases, RDF/A is much
worse design, concluding that the assumption that attributes like 'cite'
are bad design is an assumption that should not have informed the design
of RDF/A. Whether the cite attribute can still be used is irrelevant to
my concern.

>CSS may eventually develop the ability to style HTML elements according
>to the RDF triples they express. Whether CSS chooses to make the styling
>of RDFa-qualified elements part of its scope is, of course, not part of
>our scope.

>I want to stress that our goal isn't to simplify stylesheets, it is to
>enable, as simply as possible, the expression of RDF in HTML.

That is precisely the problem. To say it with the words of Joel Spolsky:

  Don't start a business if you can't explain what pain it solves,
  for whom, and why your product will eliminate this pain, and how
  the customer will pay to solve this pain.

Being unable to express RDF in HTML is not a pain that keeps authors up
at night. Solving this "problem" will, in itself, not solve any problem
authors or content providers or search engine developers or anyone else
might have.

If the goal of the group would be to, say, enhance HTML in a way that
encourages authors to include more machine readable information in their
documents, then you would immediately see the the contradiction between
the goal of the group and your refusal to consider the importance of
styling based on semantic markup an important constraint.

>The above example is probably written with a much earlier version of
>RDFa in mind, although, even then, it forgoes all shorthand, which
>obviously makes it look much more complicated than it needs to be.
>Here's how we would write it now:
>
>===========
> <div about="http://example.org/myfoo">
>    <meta property="dc:title">MyFoo Financial Report</meta>
>    <meta property="dc:description">$three $bar $thousands $dollars
>$from 1998 ..."</meta>
>    <meta property="dc:publisher">Example Organization</meta>
>    <meta property="dc:date">2000-04-11</meta>
>    <meta property="dc:format">image/svg+xml</meta>
>    <meta property="dc:language">en</meta>
>
>   <link rel="dc:creator" href="#authors" />
>   <ul id="authors">
><li>Irving Bird</li>
>        <li>Mary Lambert</li>
>   </ul>
></div>
>===========

This has nothing to do with the example I gave; my example was included
in the <head> of the document, and you cannot use <div> or <ul> there.
As such, I do not see the relevance of your code example.

>Many of your comments have been implicitly addressed with subsequent
>revisions of RDFa. We invite you to review the latest RDFa working draft
>and reevaluate your comments in light of those developments.

There is no such thing as a RDFa Working Draft; there is the XHTML
2.0  Working Draft which does not mention "RDFa" at all, and there is
a "Primer" which is neither a specification nor a reasonable reading;
just consider that the previous Working Draft had code like:

  <html>
      <head>
          <title>Jo Lambda's Home Page</title>
      </head>
      <body>
          <p>
              Hello. This is Jo Lambda's home page.
              <h2>Work</h2>
              If you want to contact me at work, you can
              either <a href="mailto:jo.lambda@example.org">email
                  me</a>, or call +1 777 888 9999.
          </p>
      </body>
  </html>

I said this many times before, you need to take "RDFa" back to the
drawing board, come up with an actual problem to be solved, gather
requirements, and build a solution under the auspices of the W3C
process. What you have now will never make it into a Candidate Re-
commendation.
-- 
Björn Höhrmann · mailto:bjoern@hoehrmann.de · http://bjoern.hoehrmann.de
Weinh. Str. 22 · Telefon: +49(0)621/4309674 · http://www.bjoernsworld.de
68309 Mannheim · PGP Pub. KeyID: 0xA4357E78 · http://www.websitedev.de/

Received on Friday, 8 September 2006 02:40:36 UTC