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Discussion with Ian and Henri about HTML5+RDFa (part 2/2)

From: Manu Sporny <msporny@digitalbazaar.com>
Date: Mon, 19 Jan 2009 19:01:55 -0500
Message-ID: <49751473.3060407@digitalbazaar.com>
To: RDFa mailing list <public-rdf-in-xhtml-tf@w3.org>
CC: Ian Hickson <ian@hixie.ch>, Henri Sivonen <hsivonen@iki.fi>

Discussion with Henri Sivonen
-----------------------------

Henri had two major disagreements with RDFa as it stands right now.

CURIEs
------

Henri stated that the use of xmlns: will break the DOM Consistency
Principle between XHTML and HTML. I let him know about @prefix, which
would address the DOM Consistency Principle issue, but would still not
be good enough in his mind. He is most concerned with HTML authors
cutting and pasting snippets of RDFa that they believe to contain
triples, but when pasted, fail to generate any because the prefix
mappings were declared at the top of a page.

He was also concerned that authors would get frustrated when their
cut/paste RDFa did not produce the same triples that they saw on website
X... or worse, they wouldn't check it and would see no benefit by
embedding RDFa in their website.

To address this issue, he (and Dan Brickley) believe that allowing
@typeof, @property, @datatype and @rel/@rev to accept URIs would address
this issue with the people in WHATWG that don't like CURIEs. They
believe CURIEs are too fragile as implemented and it would be better to
specify all URIs fully instead of providing a prefixing mechanism.

Non-expert usage and RDFa Education
-----------------------------------

Education about RDFa would also be an issue with the majority of web
authors who don't care about web semantics and just want to get their
page operational.

He was concerned that authors who once used rel="license" are now being
asked to embed more complex metadata (such as Creative Commons licenses)
without truly grasping the subtleties of doing so (attaching them to the
wrong subject). This is an issue because bad semantic markup doesn't
generate the same sort of jarring page display issue that bad HTML
markup does.

The problem is with less-than-guru web authors who don't necessarily
care about web semantics and thus generate bad semantic data out of
ignorance. The common mis-use of @rev was cited as one possible outcome
- mis-used so badly that it is commonly not trusted by search engines.

Vocabulary Scalability
----------------------

He also did not believe in follow-your-nose to be a very useful concept
and noted that even if we continue down the @prefix and
Microformats-like RDFa markup routes, with special tokens/reserved words
specified in a separate file, it could cause a scalability issue when
vocabularies find themselves quite popular. The example of the W3C
serving up many, many gigabytes of the same HTML4.01 DTD every day was
cited as an example of what happens when your "vocabulary" becomes popular.

He was concerned that by requiring parsers to load references from a
remote file that one would either put the burden on web authors to stash
those files on their web servers or put the burden on vocabulary authors
to ensure that their vocabulary document can be transmitted millions of
times a month.

He cited that using something of the form of a pseudo-namespaced
"foaf-foo" where each token was specified in a spec somewhere, but there
was no way to follow your nose to it, or validate against it, would
solve the "failure-due-to-popularity" issue.

Henri was certainly sympathetic to embedding semantics in HTML for
everyone that needed the functionality (not just the 80% that
Microformats addresses) in HTML. He believes that removing CURIEs would
go a long way towards addressing his concern with the way RDFa is
currently implemented.

-- manu

-- 
Manu Sporny
President/CEO - Digital Bazaar, Inc.
blog: Bitmunk 3.1 Website Launch
http://blog.digitalbazaar.com/2009/01/16/bitmunk-3-1-website-launch
Received on Tuesday, 20 January 2009 00:02:35 GMT

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