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Re: RDF in XHTML [was: Re: Authors describing what their URIs mean]

From: Seth Russell <seth@robustai.net>
Date: Sun, 15 Apr 2001 16:59:54 -0700
Message-ID: <003401c0c608$2ce1afc0$b17ba8c0@c1457248a.sttls1.wa.home.com>
To: "Danny Ayers" <danny@panlanka.net>, "Sean B. Palmer" <sean@mysterylights.com>
Cc: "Joshua Allen" <joshuaa@microsoft.com>, "RDF Interest" <www-rdf-interest@w3.org>
From: "Sean B. Palmer" <sean@mysterylights.com>

> Yes, because RDF in (X)HTML does not conform to any grammar
> specifically published by the W3C as a recommendation to this date
> (unless you create a grammar yourself, a la XHTML Modularization [1]).

Thanks for the pointers, I think I understand the technical side of this
now,  it's the political side that is still giving me head aches.

Shouldn't there *already exist* a general purpose module written to the
Modularization Spec [1] which defines a document type such that authors can
embedded the RDF description of their resources in those resources?  Why
can't I find it?

[1]  http://www.w3.org/TR/xhtml-modularization

I mean the W3C has already endorsed this practice:

     "This document has been reviewed by W3C Members
       and other interested parties and has been endorsed by
       the Director as a W3C Recommendation. "

What am I missing?

> > There must be some way for authors to correctly describe their
> > web documents with RDF embedded in the documents.  The
> > problem is not that this particular example fails validation, the
> > problem is how to embed RDF in a www document
> > correctly.
> Let's see... how many tools can extract RDF from HTML at the moment?

Well for one, Jason Diamond's RepatCOM.RdfReader [3] which is being used by
our Sembrowser [4] will extract triples from the page ... you can point it
at the example [5] and verify this for yourself.  I would hazard a guess
that Redlands works as well.

[3] http://www.injektilo.org/
[4] http://groups.yahoo.com/group/sem-dev
[5] http://robustai.net/rdf-commons/ex7.html

> How many can scrape it from RDDL links, or the HTML <link/> element? I
> think the answer varies between "none" and "very few". The main thing
> that is holding us all back is the lack of validation: it is simply
> next to impossible, unless you use the recent XHTML m12n
> recommendation [1].

Well I like Joshua Allen's more practical approach to this, see [6].  I
don't think that validation is all that important in this rapidly growing
field ... it appears, to me, to be just an excuse to hold back.  The need
for authors to describe the semantics of their web pages eclipses the desire
for a page to be validated by a couple orders of magnitude.   When we get
the authors descriptions on their pages, then the bookmarking process itself
will be able to remember the bookmarked page in semantic memory permitting
smart retrievals.  But when we get the pages to validate (which we will
someday), very few people will even know or care.

[6] http://lists.w3.org/Archives/Public/www-rdf-interest/2001Apr/0204.html

>FWIW, I published a very simple module for Dublin
> Core in XHTML ages ago [2]. Note that this might not be a valid XHTML
> Module. I'll update it if anyone really wants me to.

see [2] http://xhtml.waptechinfo.com/modules/rdf/rdf.mod

This is great ... proves that we can do it ... right?   But, me thinks, we
need a general purpose RDF module ... one where we can just include whatever
namespace we want to .. it's not practical for each author who wants to use
a RDF term from a new schema, to make up another DTD.   Hasn't this
Modularization technique provided for defining the RDF element in such a way
that every namespace defined within the RDF in the document is automatically

> Another idea is to simply link to the RDF file, either using a
> HyperText link, or a document metadata profile giving an appropriate
> link type.

I suppose that would work as well just as long as it became the standard
method for a automated agent to find the author's description of the page
and what it's URI signifies.  But I doubt that it will be useful for us to
invent something ad hoc; rather we need to get everybody to do it the same
way, and that means the W3C needs to stand up and say .. do it this way.

Yet I don't even see this on their issue tracking page :(

> As for best practices, getting the thing to display, just make sure
> you use the shortened RDF syntax (using elements and attributes, no
> content) for your embedded RDF.


Let's do it!
Received on Sunday, 15 April 2001 20:06:44 UTC

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