Re: Meaning and priority of standard XHTML properties

Hi Shane,

I think you are right.

However, there is a sort of 'principle' that I have been working to in
my mental model of RDFa and its relationship to the DOM, which is that
an RDFa processor actually adds the properties to the DOM as it
parses. I mentioned this on one of the SWBP telecons a while ago, and
it turns out that Ben has also been thinking along the same lines, and
that's subsequently how he has implemented his Firefox plug-in, which
shows it can work.

So in this approach you don't need the findMeta() method, since the
metadata is there in the DOM for you to get. (You might add a SPARQL
query processor...but that's another story!) This seems to me to put
the onus on the RDFa processor to do the work--and what's more this
whole thing can easily be done in script.

It also means that the following two statements are equivalent in UAs
that support RDFa:

  <div role="wai:toolbar">
    ...
  </div>

  <div>
    <link rel="role" href="[wai:toolbar]" />
  </div>

Now...of course this is all completely absent from the spec! But I'm
not completely sure that it should be in there yet anyway--even if we
agree on this approach--since we don't talk of the DOM in XHTML 2
anyway, do we? So I would think that XHTML 2 is ok for now, and we
could probably get away with simply saying that there is an
'equivalence' between the two syntaxes, and then leave it to some
DOM-related spec to spell out what that means at the DOM level.

What do you think?

All the best,

Mark

On 15/06/06, Shane McCarron <shane@aptest.com> wrote:
>
> Actually, there is more to it than this.  I appreciate that what we are
> saying is that the meta element allows the specification of certain
> metadata properties about the document or about segments of the
> document.  However, this is completely separate from the setting of
> XHTML attribute values.  The fact that there is a title attribute on
> every element, and that there is also a potential title metadata
> property, is no doubt intentional.  But I do not think that we can
> require that XHTML conforming user agents somehow overlay that property
> onto the attribute value....
>
> It is fine to require that the attribute value be interpreted as an RDF
> predicate, since that is specialized processing.  The RDF-ness of XHTML
> is a happy side effect that can be derived by RDF-aware agents.  It is
> not something that I think we are mandating be available in every user
> agent.
>
> So, what am I driving at here?  It comes down to the XML DOM.  If I am
> relying upon that DOM and its structure to find information about a
> document, and I want to know the title associated with an element, I am
> going to look at the value of the title attribute.  I am NOT going to
> hunt around for random meta elements that are children of that element.
> I am surely NOT going to look for meta elements anywhere in the document
> that might have an about attribute that references my target.  That
> would be insane.
>
> My proposal here is simple but potentially destabilizing:  Change the
> property attribute value "title" to something else.  Decouple that
> particular piece of metadata from the markup.  For now, I will call it
> "bagel".  If we like, we *could* say that when processing XHTML
> documents using RDF aware parsers, a triple is *also* formed based upon
> the title attribute of an element, if any.  That would at least garner a
> lot of fun metadata for free (every href with a title has some
> semantics).  But if we just decouple these then there will be no
> confusion and no expectation that the DOM does anything to attempt to
> propagate these "properties" into the corresponding attribute values.
>
> In addition, I recommend we design a DOM extension (optional DOM
> feature?) that allows me to explicitly search for this type of
> metadata.  document.findMeta(idref, propertyName) or something.  At
> least then I would know if I had some portable way to try and find this
> stuff.  Otherwise, I think we are violating the principle of least
> surprise - and that is never good.
>
> Steven Pemberton wrote:
> >
> > We have said in XHTML2 that things like
> >
> >     <a title="gezellig" href="gezellig.html">gezellig</a>
> >
> > is equivalent to
> >
> >     <a href="gezellig.html">
> >         <meta property="title" content="gezellig"/>
> >           gezellig
> >       </a>
> >
> > The question has arisen, what happens with:
> >
> >     <a title="Peioria" href="gezellig.html">
> >         <meta property="title" content="gezellig"/>
> >           gezellig
> >       </a>
> >
> > From an RDF point of view, there's no problem (the element has two
> > titles) but what should a browser do with respect to, for instance,
> > tool tips?
> >
> > Steven
> >
>
> --
> Shane P. McCarron                          Phone: +1 763 786-8160 x120
> Managing Director                            Fax: +1 763 786-8180
> ApTest Minnesota                            Inet: shane@aptest.com
>
>
>
>
>


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Received on Thursday, 15 June 2006 09:31:32 UTC