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Re: Evaluation Results In XML - SSB Technologies Thoughts

From: Charles McCathieNevile <charles@w3.org>
Date: Fri, 27 Oct 2000 11:23:20 -0400 (EDT)
To: Timothy Stephen Springer <timsp@ssbtechnologies.com>
cc: WAI ER IG List <w3c-wai-er-ig@w3.org>
Message-ID: <Pine.LNX.4.21.0010271120260.26905-100000@tux.w3.org>
Hi all. 

I put together a sample XML file of conformance to specs as one of the form
field values at http://www.w3.org/1999/11/11-WWWProposal/atagdemo in the form
of RDF.

The simple schema outlined there can be readily adapted (I have an action
item from somewhere to do it, and there was a thread here on how to) and can
already be used to specify a lot of the stuff required, by making the
conformance statements refer to AERT URIs instead of ATAG checkpoints (as in
my example) or just being XML statements (as in Chris')

Because this stuff is metadata, and uses URIs as pointers it doesn't need to
involve editing the document itself at all.

Charles McCN

On Wed, 25 Oct 2000, Timothy Stephen Springer wrote:

  	I have put together a short set of ideas for a what a possible XML
  evaluation document could look like.  To begin the conversation here is a
  quick proposal of what such a document could look like:
  <?xml version="1.0" encoding="UTF-8"?>
  <!-- PI if we want to define a DTD / schema for verification -->
  <PAGE url="http://www.yahoo.com">
    <VIOLATIONS priority="1" total="optional">
      <VIOLATION key="foo" total="optional">
        <ELEMENT line="optional">
  		 <!-- XHTML opening tag for element -->
  	     <IMG src="here" alt="Wretched Alt" />
  Primarily I would suggest initially limiting the scope of the evaluation
  document to capturing data relating solely to the violations for a
  particular page, rather than combining the page itself and violation data.
  This will limit the scope of the document, solely to evaluating the
  accessibility of a page.  The reason I would give for this is that the
  response we [SSB Technologies] have been getting from the market is that
  developers seem to want evaluation independent of repair.  For most sites
  that have dynamically produced content evaluation and repair are very
  distinct issues and data portability between the two has limited appeal.  If
  we preserve the original document state we are assuming that doing so will
  allow us to create separate evaluation and repair tools that use XML to
  transport data between.
  My experience, however, has been that the vast majority of web developers
  consider evaluation and repair separately.  Thus a schema that combines the
  two may well just add more unnecessary work.   When evaluating a document
  the developer wants to know what the issues are.  They want summary reports
  and information sorted by priority.  Evaluation data should answer the
  	1.What must I do?
  	2.In what order must I do it in?
  To this end a document that orders violations linearly by way of the
  original HTML v. by priority weakens our ability to address these questions
  succinctly.  Concretely assuming we create an XML evaluation file [XML of
  the form proposed by Chris] that maintains a version of the original HTML
  document.  With that document one cannot produce priority ordered or summary
  reports via XSLT.  This is due to the current constraints of XPath and XSLT.
  (I won't get into the why of this here but would be happy to discuss it off
  the list).  Whereas if the evaluation document is focused on report
  production (which is what I think the demand is for) such a report can be
  With that said I must admit that a solution that retains the original
  document would be the most elegant.  While I think it may not be *totally*
  necessary it does seem to be the best solution.  My only concern would be
  that in preserving the original document we retain a way to extract
  "reporting" information from the underlying XML doc via XSLT.
  The second issue I would like to address is the DTD / schema for the
  document.  I believe that it is important that all evaluation tool makers
  should be able to extend the document to export custom data.  To this end it
  is important that we maintain an unrestrictive document.  I am not well
  versed in DTDs or XML schemas to know the technical language for this but my
  proposal is simple.  Define a base set of required elements & attributes but
  allow tool authors to add additional elements & attributes while maintaining
  a valid document.
  The third issue is that of having a particular unique identifier for each
  possible violation.  I am open to this however there are some important
  considerations.  Primarily we currently divide the WCAG based on the
  underlying architecture of the program.   To give an example our program
  flags "Images without alt attributes", "Images with null alt attributes" and
  "Images with suspicious alt attributes" all as different violations.  We do
  this because it gives the most detail to our clients as well as mapping to
  our programmatic architecture.  Is this division dictated by the W3C? No.
  Are we altering the WCAG in doing so? No, just being practical in our
  approach to dividing it.  So what does this mean?  It means that the
  division of violations can be subjective based on underlying programmatic
  architecture.  Thus if we get into the business of assigning particular
  violation identifiers we have to be careful to either make them:
  	1. Map to the architecture of evaluation engines or
  	2. Independent of the architecture of evaluation engines
  Going the later route means that we will have to be less specific,
  obfuscating the nature of the problem.  Going the former means that we are
  writing practical specifications and we may have to make tradeoffs based on
  current technical feasibility.
  Pursuant to the above, another question arises from defining specific
  divisions of the WCAG.  Who should maintain the text that describes the
  violation?  I envision these descriptions in the vein of those included with
  Bobby and A-prompt.  I would prefer that the W3C maintain descriptions of
  violation problems.  The idea being that if the W3C maintains the
  descriptions it will avoid re-writes of the guidelines that could "weaken"
  the accessibility violation.  To give an example company eAccess (I have no
  idea if this is a real company.  Hope note) builds an evaluation product
  that tests all of the WCAG.  They profess to be compliant with the WAI but
  include their own descriptions of accessibility.  For IMG alt violations
  their descriptive text mentions that "page authors should include alt tags
  only if they feel like it, or on every other Tuesday."   Obviously an
  extreme example but I believe tinkering with the wording of the violations
  should be out of the hands of companies trying to evaluate accessibility.
  Finally (sorry this is so long) it makes sense to store the elements in the
  evaluation document (however that ends up) in XHTML.  The arguments for this
  our fairly simple:
  	1. It is a more accurate representation than storing them as CDATA
  	2. It should be fairly easy to do with an evaluation engine that builds a
  DOM (Document Object Model)
  	3. It will speed adoption of XHTML
  Okay that's it!  I have attached to this e-mail copies of the proposed XML
  file as well as a copy of the XML we currently produce with InSight (our
  evaluation engine).  While by no means complete they should both be good
  food for thought.
  -----Original Message-----
  From: w3c-wai-er-ig-request@w3.org
  [mailto:w3c-wai-er-ig-request@w3.org]On Behalf Of Chris Ridpath
  Sent: Monday, October 23, 2000 8:52 AM
  To: WAI ER IG List
  Subject: Evaluation Results In XML
  We have been working on a means of storing the accessibility evaluation of
  an HTML document. Our current approach is to store the evaluation in an XML
  document. The XML doc contains the original HTML with any accessibility
  problems marked with new XML elements. For example, the following snippet
  contains the evaluation of an IMG element that is missing the 'alt'
  <problem problemName="MISSING_IMG_ALTTEXT" problemID="1234">
  <![CDATA[ <img src="rex.jpg" longdesc="rex-desc.html">]]>
  The XML file that contains the above evaluation is attached to this message.
  Each accessibility problem is given a code number so it may be referenced.
  A report tool can take the XML document and prepare a report of
  accessibility problems.
  A repair tool can take the entire document, or pieces of the document, make
  repairs then update the original XML document.
  The original XML document can be easily converted back to HTML by XSLT or a
  simple program.
  If the group can agree on a set of specifications then all tool makers can
  generate and use the same XML evaluation document.

Charles McCathieNevile    mailto:charles@w3.org    phone: +61 (0) 409 134 136
W3C Web Accessibility Initiative                      http://www.w3.org/WAI
Location: I-cubed, 110 Victoria Street, Carlton VIC 3053, Australia
September - November 2000: 
W3C INRIA, 2004 Route des Lucioles, BP 93, 06902 Sophia Antipolis Cedex, France
Received on Friday, 27 October 2000 11:23:42 UTC

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