The OWL Working Group had intended to delegate our URI abbreviation
mechanisms both for in-spec and in-concrete-syntax use. OWL has a
number of different concrete serializations (including 2 XML based and
2 non-XML based), all of which use (or I would like to use) CURIEs.
Unfortunately, while trying to use the CURIE spec, I (and others) have
found that the current CURIE spec does not meet the WG needs even
putting aside concerns about the ultimate disposition of the document:
1) For non-XML host language: The CURIE spec provides no mechanism
(although it provides permission) for excluding characters from the
syntax of the local part of CURIEs. This means that in host languages
which use symbols like ")" or "[" as part of their syntax, we run into
parsing ambiguities. Note that safe CURIES do not solve this problem
as the safe CURIE delimiters are common host language delimiters.
PROPOSED FIX: Ideally, there would be a "mimimalistic" CURIE profile,
ideally something like SPARQL's abbreviation mechanism. Even QNames
would be fine (though we'd recommend the spec point out that to cover
all URIs there should be a non-abbreviated form).
Note that *permission* to make a subset isn't all that helpful. I
mean, then we're just doing our own thing, yeah?
EDITORIAL NOTE: Many of us found the organization of the spec, and
especially of the normative parts, very confusing. See:
<http://www.w3.org/mid/943ed7de-fbc9-4110-b17b-af9f8043a...@cs.man.ac.uk
>
I suggest that "Usage" and "Examples" be consolidated, and that there
are two normative sections, "Syntax" and "Incorporating CURIEs into
Host Languages" which contain the respective constraints. The second
section could usefully be broken down into "XML host languages" and
"Non-XML host languages".
2) For XML host languages: The requirement to support the XML
namespace based prefix declaration mechanism, even when an alternative
mechanism is supplied, is simply a non-starter. Many in the XML world
are hostile to the namespace based overloaded (even for proper QNames!
see RELAX NG and Schematron). But being forced to support *two*
mechanisms, especially when one of them isn't desired, is
unnecessarily restrictive and leads to the second mechanism not being
used:
<http://www.w3.org/mid/29397.1237034...@ubehebe>
3) For XML host languages: There's no reason not to have a standard
prefix declaration mechanism in the XML namespace. What value is there
in letting XML host languages coin a bunch of different ones?
For example, <xml:Prefix name="" IRI=""/> is (basically) the syntax
we're adopting, except with Prefix in the OWL namespace.
4) Processing: In some languages, multiple declarations of a prefix
have an overriding behavior. In OWL we chose to make that a syntax
error. The CURIE spec should make clear the processing model.
To sum, I, personally, don't think the CURIE spec helps either with
implementation interop or with spec factoring, though I think it could
be made to. Thus, in its current form, there's no point in citing it
and, thus, no real point in it being a recommendation. The minimal
necessary changes from my pov are:
A) A proper XML mechanism with no requirement to suport xmlns
B) Sensible profiles (I suggest, QName/RDF, SPARQL, and ALL)
C) A processing model
C could maybe be dropped. A is totally required. I just won't adhere,
or recommend anyone adhere, to the requirement to use xmlns. It's a
nonstarter. Thus I won't use or recommend people use the CURIE spec
(in its current form) for XML based host languages.
I won't use or recommend citing the CURIE spec without B for non-XML
host languages. If you are happy with this being "using curies" then
ok :)
Hope this helps.
Cheers,
Bijan.
