W3C home > Mailing lists > Public > public-rdf-in-xhtml-tf@w3.org > June 2003

Re: Validating XHTML with embedded RDF (was Re: Scenario: Trackbacks)

From: Joseph Reagle <reagle@w3.org>
Date: Mon, 16 Jun 2003 18:06:24 -0400
To: Masayasu Ishikawa <mimasa@w3.org>
Cc: public-rdf-in-xhtml-tf@w3.org
Message-Id: <200306161806.24818.reagle@w3.org>

Mimasa, thank you for the informative email!

On Thursday 12 June 2003 15:11, Masayasu Ishikawa wrote:
> Well, the validator is just a starting point.  There're quite a few
> constraints that DTD cannot express.  And when it comes to embedding
> RDF/XML in XHTML, I have no hope to work out a DTD-based solution.

Do you mean technically, or from an ecology point of view? If I understood 
Sean's proposal in [a] it appearred possible to write a RDF-in-XHTML DTD 
Modularization. It's unsavory, from an ecology point of view, because one 
doesn't want to do this for every XML combination. However, in the shorter 
term, this task force needn't solve that larger problem. Could the W3C 
issue a RDF+XHTML DTD modularization while we also worked on a solution to 
the larger problem?

[a] http://infomesh.net/2002/rdfinhtml/#embedAndValidate

> I wrote an experimental XML Schema for "extensible" XHTML 1.0
> Transitional [5], which is an extension of the XHTML 1.0 Schema
> published as a W3C Note [6].  The Schema included in that Note
> was designed to be a "closed" schema, i.e. it didn't allow
> foreign namespaces.  On the other hand this schema is an "open"
> schema, i.e. it allows foreign elements and attributes on most
> places, with processContents="lax" rather than the default value
> of "strict".

That is certainly cool.

> Another approach is to use Modular Namespaces (MNS) [7], I wrote
> MNS schemata for XHTML 1.0 Strict [8], Transitional [9], and
> Frameset [10].  These schemata use corresponding RELAX NG
> schemata to check validity of the XHTML part, but foreign
> elements and attributes (such as RDF) are ignored by pruning them
> before validation.  If you care to try, an XHTML 2 version is also
> available [11].

Cool too!

> In both cases you may check strict validity of the XHTML part
> (actually much better than DTD) while embedding RDF/XML almost
> anywhere you like.  Of cource neither of them would provide
> solution to define the semantics of such a mixed document, but
> at least they could provide some way to overcome validation issue.
> In the future, I hope ISO/IEC DSDL VCSL could provide better solution.

Do you mean DSDL VCSL would provide a better solution to the "semantics" 
problem? If so, I've looked at [a] and don't follow. 

[a] http://www.y12.doe.gov/sgml/sc34/document/0363.htm

> If you look at the latest XHTML 2.0 draft, you'll notice that
> the Metainformation Module now allows nesting of the meta element [12].
> This is a step forward to allow RDF/XML-like encoding of metadata
> through the meta element, as Micah/Steven proposed.

I looked at [12] and wasn't sure what you meant, and searched for "recurs" 
and "nest" and didn't see the relevant text?

> > If so, why not? (I think at the
> > plenary Steven mentioned something about a lack of internal user
> > defined entity support?)
>
> Well, that's a long story, and I'd love to separate entity problem
> from validation issue.  Unless RDF folks are willing to provide
> DTD for RDF, that point is rather moot and I don't think this task
> force is an appropriate place to solve that problem.

If that's an unrelated problem, all the better (keeps things simple), but my 
understanding was that the XHTML community would resist XML Schema 
proposals, akin to what you've already proposed [5] and stated "For XHTML 
2, I have hope". So I'm trying to understand how well grounded that hope is 
and if there's technical objections to it. <smile/>

> [5] http://www.w3.org/People/mimasa/test/schemas/SCHEMA/xhtml1-loose.xsd
Received on Monday, 16 June 2003 18:06:28 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Tuesday, 8 January 2008 14:14:58 GMT