Re: GRDDL and OWL/XML

On May 12, 2008, at 8:55 PM, Dan Connolly wrote:

> On Sat, 2008-05-10 at 00:39 +0100, Bijan Parsia wrote:
> [...]
>> 3) When you have a normative spec for a transformation function (as
>> OWL does), adding an XSLT sets up a 'second variant' of the spec (as
>> well as being a blessed implementation) and one that gets directly
>> used in spite of it being nominally informative. This is a violation
>> of DRY (don't repeat yourself) and divides attention from verifying
>> the actual spec (e.g., with multiple implementations). Worse, bugs in
>> the program become part of the de facto spec.
>
> That's a reasonable argument for not using GRDDL to relate
> OWL 2 to RDF/XML. If the OWL 2 WG doesn't think that it can manage
> a reference implementation of the transformation in XSLT*,

(Remember I think that the W3C shouldn't provide reference  
implementations at all, so I would make a strongly claim.)

> then it shouldn't use GRDDL.

But I don't think GRDDL requires a reference implementation, nor is a  
reference implementation a requirement for the utility of GRDDL  
(e.g., of working with GRDDL implementations to make sure they  
recognize the normative translation; I think variant transformations  
might be useful in various contexts as well, e.g., just the class  
tree (but fully classified) instead of a translation of the asserted  
axioms; similarly, I might provide *approximation* functions).

So i see a lot of potential for reasonably coordinated specification  
of transformation, which is what I understand to be the essence of  
GRDDL.

> * or maybe XQuery, though it's hard to imagine the difference
> between XSLT and XQuery making or breaking the case.

It doesn't for me.

> [...]
>> I feel fine in asking a W3C wg to provide a specification *for the
>> transformation function*, but it should not be the presumption that
>> saying "Support GRDDL" means providing an implementation.
>
> Presumption? It's a straightforward reading of the GRDDL spec, no?
>
> "Developers of transformations should make available  
> representations in
> widely-supported formats. XSLT version 1[XSLT1] is the format most
> widely supported by GRDDL-aware agents as of this writing ... ."
>  -- http://www.w3.org/TR/grddl/

People are reading the SHOULD as a MUST. That's what I object to. My  
straightforward reading of the spec is that it is SHOULD. In any  
case, we supply the transformation in HTML which is way more popular  
than XSLT :) (albeit, not with GRDDL-aware agents).

(I certainly wouldn't might pointing to a *set* of implementations of  
our transformation functions, including web services, etc. Then the  
GRDDL agent could ask the user which to use/install/whatever. As long  
as the namespace document is actively maintained, that's not so bad,  
furthermore, it can point to other lists...)

Cheers,
Bijan.

Received on Monday, 12 May 2008 23:05:15 UTC