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Re: HTML5 ISSUE-120 rdfa-prefixes : Proposal to use RDFa according to spec

From: Michael Brunnbauer <brunni@netestate.de>
Date: Fri, 4 Feb 2011 13:37:40 +0100
To: semantic-web@w3.org
Message-ID: <20110204123740.GA11310@netestate.de>

re

Can we handle false statements ? Can we handle *lots* of false statements ?

If yes we can make it as easy as possible to generate triples.

Personally I think we are not ready and should be cautious.

Have a look at http://data.totl.net/dave.rdf

Ok this may be a bad example because its deliberate. But think about something
like that in your favorite semantic web application.

Regards,

Michael Brunnbauer

On Fri, Feb 04, 2011 at 10:35:47AM +0100, Danny Ayers wrote:
> ISSUE-120
> Current Status [1,2] :
> >   We a single change proposal to simplify the HTML+RDFa specification
> >   by removing prefixes.
> > - We have another change proposal to clarify how prefixes work and
> >   explain that they are optional.
> 
> I'd like to propose that HTML/HTML5 uses RDFa as found in the RDFa
> specification [3]. This includes the use of namespace prefixes.
> 
> I'll counter the argument for changing the spec in regards to
> namespace prefixes given (by Hixie) on the WHATWG Wiki [4]
> (statistical evidence is my trump card), and then also offer a
> sub-proposal that may help alleviate the perceived problems (but isn't
> tied to the main proposal).
> 
> The Change Proposal summary (regarding namespace prefixes) is:
> Simplify the specification by removing features that are documented to
> be confusing to users.
> 
> First, this change is unnecessary as the use of namespace prefixes is
> optional (full URIs can be used inline instead). If this feature is
> actually confusing to users then confusion may be avoided by only
> providing guidance in the HTML documentation on the use of RDFa
> without prefixes. If the facility coverage is adequate, then the user
> won't have any need to consult the RDFa spec for the namespace
> prefixes-based alternative.
> 
> Second, the arguments given in the Change Proposal that support for
> namespace prefixes is confusing are mostly anecdotal - i.e. person A,
> B and C say it's confusing. (Given the size of the Web, such material
> isn't in short supply on any issue you wish to choose - given a little
> time with a search engine, arguments that the British Queen is an
> alien lizard can be amassed). Additionally no real distinction is made
> between issues faced by end-user publishers and tool developers. This
> is significant because the only time full knowledge of the namespace
> prefix mechanism is essential is when developers wish to write a
> parser - this seems something of a minority activity.
> 
> Statistical evidence [5] would suggest that in reality the existence
> of the option to use namespace prefixes* isn't a barrier to widespread
> deployment of RDFa: "The data shows that the usage of RDFa has
> increased 510% between March, 2009 and October, 2010, from 0.6% of
> webpages to 3.6% of webpages (or 430 million webpages in our sample of
> 12 billion)".
> 
> (* It's possible that none of the pages analysed actually used
> namespace prefixes, but that would still mean that their appearance in
> the specs doesn't compromise the use of RDFa as-is)
> 
> A usability study is quoted, but as an internal Google study which was
> flawed in design and limited in scope, I don't believe this can be
> considered credible evidence.
> (Personally my biggest issue there was that there were only 7
> participants, but Hixie has assured me that conclusions can reasonably
> be drawn from such small numbers of participants. On the blog it
> states "people really don't have any problems dealing with URLs as
> property names" - but as also stated there, this wasn't something that
> the study was designed to test. A casual observation is not evidence.
> There are also the issues mentioned in comments on the WHATWG blog [6]
> : "Videos can???t be viewed out of Google. Bias on the part of the
> creators of the study. Lack of outside involvement. No information
> about where the people taking the study are employed. Lack of
> diversity of demographics. Lack of proper, and neutral, oversight.
> Interpretation by person or persons without proper background, and
> neutrality. Single study, only.")
> 
> ---
> 
> So onto a sub-proposal: a way of removing the need for the widespread
> use of namespaces, and allow the use of short names rather than URIs
> for common terms, would be to put such terms in the HTML namespace. In
> other words, make a registry of terms along the same lines as already
> used for common rel="" attributes. Of course such a registry could
> never completely reflect the range of terms found in the wild, but it
> does seem likely that in the near term at least, HTML developers are
> most likely to predominantly use a limited range of terms, which could
> be catered for in the HTML namespace.
> 
> This is akin to the approach taken by Google in their "Rich Snippets":
> common terms are placed in a single namespace. As noted elsewhere, the
> single-namespace approach is "hobbled" [7] and Google's particular
> implemention is severely flawed [8] (the main flaw is
> self-documenting, see http://rdf.data-vocabulary.org/name). But such
> issues could be to some extent alleviated by providing references to
> existing deployed vocabularies in the HTML namespace document, along
> the lines of:
> 
> html:Person rdfs:subClassOf foaf:Person, vCard:Person, google:Person ...
> 
> (Probably done in RDFa)
> 
> Work would be needed in selecting suitable terms (the microformats
> community could probably help there) and care taken in aligning them
> appropriately with existing terms (i.e. where and in which direction
> to use rdfs:subClassOf/rdfs:subPropertyOf,
> owl:equivalentClass/owl:equivalentProperty etc).
> 
> Were this approach taken, I'd suggest it was used alongside including
> RDFa as-is. As mentioned above, if the documentation guides the user
> towards the syntactically simpler approach, any potential confusion
> may be minimised.
> 
> Cheers,
> Danny.
> 
> [1] http://www.w3.org/html/wg/tracker/issues/120
> [2] http://dev.w3.org/html5/status/issue-status.html#ISSUE-120
> [3] http://www.w3.org/TR/rdfa-syntax/
> [4] http://wiki.whatwg.org/wiki/Change_Proposal_for_ISSUE-120
> [5] http://tripletalk.wordpress.com/2011/01/25/rdfa-deployment-across-the-web/
> [6] http://blog.whatwg.org/usability-testing-html5
> [7] http://blog.iandavis.com/2009/05/13/googles-rdfa-a-damp-squib/
> [8] http://www.jenitennison.com/blog/node/104
> 
> -- 
> http://danny.ayers.name

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Received on Friday, 4 February 2011 12:38:10 GMT

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