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Re: ANNOUNCEMENT: RDFStyles: alternative to XSLT for RDF

From: Emmanuel Pietriga <epietriga@yahoo.fr>
Date: Thu, 23 Oct 2003 10:38:50 +0200
Message-ID: <3F97939A.3000003@yahoo.fr>
To: Dominique HazaŽl-Massieux <dom@w3.org>, www-rdf-interest@w3.org
Cc: Reto Bachmann-Gmuer <reto@gmuer.ch>

Dominique HazaŽl-Massieux wrote:

> Le lun 20/10/2003 ŗ 14:17, Reto Bachmann-Gmuer a ťcrit :
>>I'm trying to develop a tool for rendering RDF-Resource to text based
>>formats such as HTML or XML.
>>The first alpha-implementation written in java is available for download at:
>>The rdf-schema can be found at: http://wymiwyg.org/ontologies/rdfstyles.rdf
> Unless I misunderstood, this is very close to GSS, an RDF style sheet
> language used by Isaviz:
> http://www.w3.org/2001/11/IsaViz/gss/gssmanual.html
> It would be interesting to see the two projects work together on this.

The current version of GSS (which is an RDF-based stylesheet language 
for styling RDF) is aimed at styling node-link representations of RDF 
graphs using CSS and SVG properties. So it's not addressing exactly the 
same issue, but there is clearly an intersection between the two.

Some precisions about GSS:

GSS also has a cascading mechanism.

The selector language defined by GSS is somewhat inspired from the RDF 
reification mechanism, so it tends to be verbose, and I'm not really 
happy with it (hopefully, the graphical front end for creating GSS 
stylesheets should hide the complexity of selectors). But GSS would 
clearly benefit from an XPath-like RDFPath language.

As far as the execution model is concerned, we can draw a (loose) 
parallel with XSLT: the GSS engine walks the entire graph (nodes and 
arcs) and tries to match them with the selectors defined in the 
stylesheet. Styling instructions associated with matching selectors are 
executed on the current node (or arc). Note that there is no mechanism 
similar to apply-templates yet as it is less obvious in the context of a 
graph structure. If several selectors are match the current node, there 
is an XSLT/XPath-inspired algorithm for computing the "longest match", 
meaning that the most specific selector is applied (*).

(*) actually, it is somewhat more complex than that, as the less 
specific selectors might still have some effect if they set a styling 
property that has not been defined by more specific selectors.

I still have to catch on this RDFStyles thread, but I would be glad to 
look further if we can collaborate on this.

Note: Ryan Lee has written an OWL Schema for GSS, available at [1] 
(informal Notation 3 version at [2]), and as Dominique pointed out, 
there is more information about IsaViz and GSS at [3] and [4].

[1] http://www.w3.org/2001/11/IsaViz/graphstylesheets
[2] http://www.w3.org/2001/11/IsaViz/graphstylesheets-informal.n3
[2] http://www.w3.org/2001/11/IsaViz/
[3] http://www.w3.org/2001/11/IsaViz/gss/gssmanual.html


Emmanuel Pietriga (epietriga@nuxeo.com)
tel (mobile): +33 6 88 51 94 98
Received on Thursday, 23 October 2003 04:38:05 UTC

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