[whatwg] Trying to work out the problems solved by RDFa

Benjamin Hawkes-Lewis bhawkeslewis at googlemail.com
Sun Jan 11 01:41:39 PST 2009

On 11/1/09 02:51, Calogero Alex Baldacchino wrote:
> eRDF might be a working compromise, because it doesn't need any changes
> to the spec

It's not possible to author conforming HTML5 that functions as eRDF 
since eRDF requires a 'profile' attribute, but HTML5 has removed the 


; RDFa covers a wider range of RDF semantics, but requires
> new attributes and also namespaces (a sort of hybrid beteween them might
> avoid the need to bring namespaces - xmlns:* attributes - into html
> serialization).

To avoid xmlns:* attributes, one could drop CURIEs in the text/html 
serialization and use markup like:

   <div about="http://dbpedia.org/resource/Albert_Einstein">

instead of

<div xmlns:db="http://dbpedia.org/">
   <div about="[db:resource/Albert_Einstein]">

There's no data loss.

> My suggestion was meant as a mean to test RDFa in HTML
> documents without changing the spec (perhaps in conjunction with
> data-xmlns-*, data-xmlns-prefixes="rdfa foaf <whatever>" to "emulate"
> namespaces - an ugly hack, I know, but at least would avoid changes to
> html serialization, at least in a test phase) -- even if I think that
> xml serialization should work better for such rdf metadata.

I really can't see anybody violating the spec in that way rather than 
violating the spec by just adding the RDFa attributes outright, 
especially given that there are already people publishing these 
attributes in text/html so the "namespace" has already been polluted and 
we already have services like SearchMonkey not only using these 
attributes but promoting them. It may therefore already be problematic 
for a future version of HTML to use these attributes as extension points 
without breaking existing sites. The "test" is already in progress, for 
better or worse. HTML5 conformance checkers don't have to bless this 
test, of course, any more than CSS validators have to give the all clear 
to vendor-specific properties.

Moreover, the damage done by immediately breaking the principle that 
data-* should be for private use only and turning it into a distributed 
extension point may be worse than the alternatives.

Benjamin Hawkes-Lewis

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