RE: XSLT and XPath-like functions in RDF/OWL ?

Hi,

 

I thank Damian, Ian, Emmanuel, and David for their responses!

 

It is good to have standards, but not too many, please! I get the impression
that this is a fragmenting world (I may be wrong, though, but ten RDF Path
languages, for example, seems a bit high).

 

As an implementer I need a clear framework of what to use in what
circumstances. An example: a couple of months ago I read about Trix and I
liked the idea. I worked out how to implement that. Then I asked the authors
of Trix whether or not it would reach Recommendation status, which seems not
likely to happen. So my work turned out to be of academic value only.

 

I need XSLT-like functionality for two reasons:

-         for mapping data of any application (say a 3D plant design
system), that conforms a system-specific XML schema, to an RDF/XML file that
conforms with a particular OWL ontology (so it's deterministic);

-         for HTML-based presention (on screen or on paper) of information,
stored in a triple store, in conformance with an OWL ontology for document
types

 

I need XPath-like functionality to be able to fetch a particular literal
related with a particular object, where that literal is hidden somewhere
deep in the triple clouds around that object, as stored in a triple store.

 

I am transferring from the world of XML Schema to the OWL world because the
latter fits better with our data modelling requirements, but I start to miss
all the standard goodies like XSLT, XPath, XQuery, etc. But perhaps I am
dead wrong, and all of this can be used in the RDF/OWL environment as well
(because RDF/XML is a kind of XML?).

 

Is there any WG in W3C that deals with implementation requirements in the
RDF/OWL environment?

 

Regards,

Hans

 

PS Below I recap the valued responses I got:

 

DAMIAN STEER

If you dig around

<http://www.ilrt.bris.ac.uk/discovery/chatlogs/swig/2005-09-04.html#T13-47-5
1>

you may find some useful links. None (as far as I know) are intended for
OWL, but I do know treehugger works over a jena model with OWL inferencing,
since I wrote it. You may want something more OWL-specific, however.

and, later:

I've tried to capture most of the projects I'm aware of in this field at:

<http://esw.w3.org/topic/RdfPath>

Needs summaries, and I bet I've still missed some.

 

IAN EMMONS

Regarding XSLT, if you are looking for a mechanism to translate OWL data
from one ontology to another, then the usual practice is to use rules
(inferencing).  There are a number of rule languages for RDF and OWL, but
one that appears to be gaining a fair bit of momentum is SWRL [1].

If you are looking for a way to translate data from OWL to another
representation, then XSLT itself is probably your best bet.

There are also many query languages for RDF and OWL, but the one that
appears to be on track for W3C standardization is SPARQL [2].  This is your
best bet as an XPath analogue for OWL.

 

EMMANUEL PIETRIGA

W.r.t XPath for RDF, you might want to take a look at FSL [1]. It features
some basic RDFS/OWL awareness w.r.t class and property hierarchies. More
might come in XPR (an extension of FSL currently being designed).

We have a full Jena implentation of it, as well as an evaluator built into
IsaViz [2] that highlights path instances matching the FSL expression in the
graph [3] (useful for FSL debugging).

[1] http://www.w3.org/2005/04/fresnel-info/fsl/

[2] http://www.w3.org/2001/11/IsaViz/

[3] http://www.w3.org/2001/11/IsaViz/images/fsl1.png

 

DAVID POWELL

One option might be to use standard XSLT and XPath over a regular XML syntax
for RDF such as RXR or TriX, which unlike RDF/XML can be processed using
XSLT.  (Although it is a bit clumsy, and the performance probably isn't
great.)

I made a script to convert RDF/XML to TriX, and then apply an XSLT
stylesheet to the result to get HTML-ised RDF Schemas here:

http://djpowell.net/rdftrix/form.html