[whatwg] RDFa Features

Ben Adida ben at adida.net
Fri Aug 29 07:56:40 PDT 2008

James Graham wrote:
> Given the problems with using DNS as your registry noted above and the
> fact that the recommended solution to this problem is to use a small
> number of registries built atop DNS that promise greater longevity than
> DNS registrations can ensure, it doesn't seem unreasonable to have a
> single permanent registry that provides (at least for HTML 5) a
> canonical prefix:url mapping.

I don't think that argument follows quite the way you frame it. Even if
the recommendation is to use long-lasting registries, you can still
choose the registry you want, build your own, etc... Meanwhile, the
centrally registered prefixes are, well, *centrally* controlled, which
is a very different architectural choice, and, where data is concerned,
not as web-like as one really wants.

> So instead of the use of cc:foo requiring
> a deceleration of cc elsewhere in the document, cc would be declared at,
> say, cc.rdfa.net and would be a globally unique prefix from the point of
> view of the author. People not wanting to bother registering would just
> have to use full URLs everywhere. This would seem to provide the "follow
> your nose" principle you desire, remove several of the objections to
> URL-based namespaces, make authoring for the common case of well known
> vocabularies easier, and have only mildly different distributedness
> characteristics to the current recommended practice.

That said, I don't think this is a bad idea at all.

In defining RDFa, we said that various host languages (HTML5, XHTML1.1,
XHTML2, ...) may choose to include some built-in additional definitions,
e.g. new reserved keywords in @rel.

I am certainly open to considering a mechanism for pre-defined prefixes
in HTML5+RDFa, as long as they are machine-discoverable by
follow-your-nose (likely via the HTML5 spec doc), and as long as those
prefixes can be overridden in a given document and new prefixes can be
defined at will.

And I appreciate this suggestion, which definitely moves the discussion


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