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Re: RDFa in HTML 4

From: Manu Sporny <msporny@digitalbazaar.com>
Date: Thu, 17 Jul 2008 18:00:08 -0400
Message-ID: <487FC0E8.6080004@digitalbazaar.com>
To: Toby A Inkster <tai@g5n.co.uk>
CC: public-rdf-in-xhtml-tf@w3.org

Toby A Inkster wrote:
>>    <div curieprefix="dcterms http://purl.org/dc/terms/
>>                      media http://purl.org/media#
>>                      audio http://purl.org/media/audio#"
>>         about="#a-song" typeof="audio:Recording">
> 
> I've suggested it before, but I'll suggest it again. RFC 2731, which was
> put forward by the Dublin Core crowd many years ago, already offers an
> HTML-compatible method for defining prefixes for metadata terms. RFC
> 2731 has been embraced by eRDF. The syntax is:
> 
>     <link rel="schema.dct" href="http://purl.org/dc/terms/">
> 
> These definitions are document wide though, so it may be necessary to
> refine the syntax to allow them to be scoped to particular elements.
> Perhaps using:
> 
>     <link about="#section-1" rel="schema.dct"
>         href="http://purl.org/dc/terms/">

Hi Toby,

The issue with the RFC-2731 approach, unless I'm missing something, is
that it doesn't allow multiple scoped prefix definitions. Take the
following example:

    <div xmlns:dcterms="http://purl.org/dc/terms/"
         xmlns:audio="http://purl.org/media/audio#"
         about="#welcome-to-the-jungle" typeof="audio:Recording">
       <span property="dcterms:title">Welcome to the Jungle</span>
    </div>

How would we accomplish doing that with the RFC-2731 approach?

The above example is a very important use case as it is how we expect
bloggers and commenters to be able to embed RDFa in some websites
(Blogger, Twitter, Wikipedia, etc.).

>> There is no HTML4 + RDFa validator, and until we can point web
>> developers to a tool that validates HTML4 + RDFa, we should not
>> encourage them to use RDFa in HTML4.
> 
> I posted this on this mailing list just yesterday - a page using a DTD
> based on HTML 4.01 Strict, but with RDFa attributes added.
> 
> http://buzzword.org.uk/2008/html4plus-example.html

Yes, which is great work! It has the issue listed above, but I expect
that what you have is very close to what we're going to end up with...
It should be noted that the ease you had in putting together a valid
HTML 4.01 Strict + RDFa DTD was by design, and we would like to take the
same care in crafting how we define prefixes in HTML 4 and 5.

However, this is all dependent on whether or not the group agrees to
approach the problem from this direction - I don't want to make it seem
like this is definitely where things are going. Just voicing one opinion
among many. Certainly not speaking for the group.

>> The goal is to enable HTML 4 + RDFa as quickly as possible.
> 
> Well, Cognition has supported RDFa in HTML 4 (using RFC 2731 for CURIE
> prefixes) since February.
> 
> http://buzzword.org.uk/cognition/

Yep, definitely noticed when that happened. It's great that you were one
of the first to jump into the deep end and implement that sort of
functionality. The concern is that we may have multiple people that
choose a different method of specifying prefixes than RFC 2731... we
don't want this stuff to fork this early because it'll just make parser
writing more complicated for those that want to support the full
language family - HTML4, XHTML 1.1, and HTML 5.

So, keep up the great work Toby - it's vital to this community that we
have people like you out in front, testing different approaches to the
problem. :)

-- manu

-- 
Manu Sporny
President/CEO - Digital Bazaar, Inc.
blog: Bitmunk 3.0 Website Launches
http://blog.digitalbazaar.com/2008/07/03/bitmunk-3-website-launches
Received on Thursday, 17 July 2008 22:00:47 GMT

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