[whatwg] RDFa Features (was: RDFa Problem Statement)

Smylers Smylers at stripey.com
Wed Aug 27 06:33:00 PDT 2008

Manu Sporny writes:

> Ian Hickson wrote:
> > > there are a number of technical merits that speak in favor of RDFa
> > > over Microformats (fully qualified vocabulary terms
> > 
> > Why is this better?
> Emulated-namespace/Pseudo-namespace (EN/PN) vocabulary terms have been
> mentioned on this list during the various RDFa discussions over the
> past week. ... This approach has been rejected by the Microformats
> community because it is believed that namespaces are more difficult
> for webpage authors to learn and are thus best if avoided due to the
> limited scope of Microformats.

Hi Manu.  Do you disagree with the Microformats community's belief about
namespaces being more difficult, or do you think they are more difficult
but that this doesn't matter?

> The approach was rejected by the RDFa community because it doesn't
> follow core W3C TAG practices and instead invents a new method of
> specifying resources on the web that are not dereference-able.  In
> short - it re-invents the URI wheel unnecessarily.

It would be unnecessary if those kind of unique prefixes have no
advantage over URIs.  However you later say:

> why we have this URL short-hand (aka: CURIEs) in the first place. It
> is a feature that helps web authors and others that are writing this
> stuff by hand to refer to long URLs in an easy way

So that is one disadvantage of URIs: they are long.  In fact they are so
long that people have gone to the bother of inventing additional syntax
to avoid having to write them out.

The other advantage of unique prefixes over URIs is the one you mention:
they are not dereferenceable.  As has been mentioned on this list, that
means nobody (human or system) will attempt to reference them, either by
mistake or in the hope of finding something there.  This avoids
confusing learners (who on seeing a URI like those you use in examples
may think that content it links to is relevant) and avoids unnecessary
server load.

(And if somebody wants information about a uniquely prefixed name, using
a web search engine will find it.)

So unique prefixes have 2 advantages over URIs; therefore they cannot be
dismissed as unnecessary merely because URIs exist.

Of course those advantages don't necessarily apply to all users in all
situations; there may be users whom don't find the above advantageous,
and prefer URIs for other reasons.  That's OK, because such users can
still choose to use a URI as their unique prefix.  (And there can be a
rule which says you are only allowed to have something which is
syntactically a URL as a unique prefix if you own that URL.)

That suggests that giving users the freedom to use either URIs or any
other prefixes of their choice is superior to forcing them to use URIs,


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