That sounds very much in line with some of our discussions.
For example, we have discussed using a GRDDL transform to go from a
simple XML doc to something more complex that has the RDF constructs in
it (Fabien Gandon was with us at TPAC). This also fits in with a
conversation I had with David Booth where, again, we talked about simple
thing -> GRDDL -> complex thing but where the semantics were always
defined in terms of the complex 'full model'.
We're mindful of the need to make sure that whatever is published as a
DR is not going to be misinterpreted by an off the shelf OWL/RDF tool.
Achieving that whilst benefiting from the expressivity of SW
technologies does seem to be pointing towards a multi-layered approach.
Phil.
Jeremy Carroll wrote:
Attempting to pull something from my hat ....
How about:
a)
- a POWDER document has a root element, typically wdr:DR, in the POWDER
namespace.
- a POWDER document is an RDF/XML document
- an RDF/XML document that uses POWDER vocabulary but does not have a
root element in the POWDER namespace is not a POWDER document
b)
POWDER documents are constrained by some schema (probably not an XML
Schema) so that they roughly follow the pattern given at
http://www.w3.org/TR/2007/WD-powder-dr-20070925/#structure
or some other similar pattern
c)
A POWDER processor follows an operational semantics, roughly following
the instructions of the various published WDs
d)
As an RDF/XML document, the formal semantics of a POWDER document is
arranged to be true, but weaker than the operational semantics.
e)
A GRDDL transform is associated with the POWDER namespace
f)
The GRDDL transform transforms
7 <wdr:ResourceSet>
8 <wdr:includeHosts>example.org</wdr:includeHosts>
9 </wdr:ResourceSet>
into
1 <owl:Class>
2
3 <owl:equivalentClass>
4 <owl:Restriction>
5 <owl:onProperty rdf:resource="&powder;#includeHost" />
6 <owl:hasValue>example.org</owl:hasValue>
7 </owl:Restriction>
8 </owl:equivalentClass>
9 </owl:Class>
etc. (i.e. the GRDDL transform embeds expert knowledge of OWL).
g)
The formal semantics of the GRDDL result of a POWDER document
corresponds closely to the operational semantics of the POWDER document.
h)
The formal semantics of a POWDER document read by a non-GRDDL aware,
non-POWDER aware, RDF processor is a proper consequence of the formal
semantics of a POWDER aware and GRDDL aware reading of the same document.
====
That seems to hit enough of the targets.
Some obvious drawbacks
It continues an overly technocractic semantic web
where there is a two-tier (or even three tier) system of formalism, with
the 'true' definitions being defined on the 'highest' plane, that is
accessibly only to an elite with a particular type of
mathematical/logical background.
There continues to be a divorce between an operational practice, that is
probably defined in terms of POWDER as XML documents, and actually
implemented using SAX and DOM like interfaces, and a theoretical model,
built on semantic web recommendations.
...
Jeremy
--
Phil Archer
Chief Technical Officer,
Family Online Safety Institute
w. http://www.fosi.org/people/philarcher/
