On Jan 19, 2009, at 02:18, Manu Sporny wrote:
Toby A Inkster wrote:
So RDFa, as it is currently defined, does need a CURIE binding
mechanism. XML namespaces are used for XHTML+RDFa 1.0, but given that
namespaces don't work in HTML, an alternative mechanism for defining
them is expected, and for consistency would probably be allowed in
XHTML
too - albeit in a future version of XHTML+RDFa, as 1.0 is already
finalised. (I don't speak for the RDFa task force as I am not a
member,
but I would be surprised if many of them disagreed with me strongly
on
this.)
Speaking as an RDFa Task Force member - we're currently looking at an
alternative prefix binding mechanism, so that this:
xmlns:foaf="http://xmlns.com/foaf/0.1/";
could also be declared like this in non-XML family languages:
prefix="foaf=http://xmlns.com/foaf/0.1/";
The thought is that this prefix binding mechanism would be available
in
both XML and non-XML family languages.
Considering recent messages in this thread, using full URIs and
refraining from declaring 'http' as a namespace prefix in XHTML would
be more backwards compatible than minting a new attribute called
'prefix'. (I haven't verified the test results about using full URIs
myself.)
Even though switching over to 'prefix' in both HTML and XHTML would
address the DOM Consistency concern, using them for RDF-like URI
mapping would as opposed to XML names would remove the issue of having
to pass around compound values and putting them on the same layer on
the layer cake would remove most objections related to qnames-in-
content, some usual problem with Namespaces in XML would remain:
* Brittleness under copy-paste due to prefixes potentially being
declared far away from the use of the prefix in source.
* Various confusions about the prefix being significant.
* The problem of generating nice prefixes algorithmically without
maintaining a massive table of a known RDF vocabularies.
* Negative savings in syntax length when I given prefix is only used
a couple of times in a file.
The reason that we used xmlns: was because our charter was to
specifically create a mechanism for RDF in XHTML markup. The XML folks
would have berated us if we created a new namespace declaration
mechanism without using an attribute that already existed for exactly
that purpose.
The easy way to avoid accusations of inventing another declaration
mechanism is not to have a declaration mechanism.
URIs already have namespacing built into their structure. You seem to
be taking as a given that there needs to be an indirection mechanism
for declaring common URI prefixes. As far as I can tell, an
indirection mechanism isn't a hard requirement flowing from the RDF
data model. After all, N-Triples don't have such a mechanism.
That being said, we're now being berated by the WHATWG list for doing
the Right Thing per our charter... sometimes you just can't win :)
Groups have a say on what goes into their charter, so it's not like a
group is powerlessly following a charter forced upon it entirely from
the outside. :-)
I don't think that the RDFa Task Force is as rigid in their
positions as
some on this list are claiming... we do understand the issues, are
working to resolve issues or educate where possible and desire an open
dialog with WHATWG.
Great!
--
Henri Sivonen
[email protected]
http://hsivonen.iki.fi/
