xml-dev - RE: RDF/XML, Node vs. Edge labeled graphs was: Re: Services-basedautomat

[Michael Rys <mrys@microsoft.com>]

Just a nitpick. Infoset is neither node nor edge-labelled. It just describes
information items (which can be either nodes or edges).

Also, XML is not inherently node-based (any tree model can either be node or
edge-labelled or both and can be transformed loss-less into each other). It
is however in my personal opinion unfortunate that the prevalent W3C specs
use node-labelled models which make it hard to add any reference types as
first class citizens into their data model. It also forces any upcoming data
model to use a node-labelled model for consistency across specs.

Best regards
Michael
--
Program Manager, SQL Server XML Technologies
Former member of the InfoSet WG and member of the Query WG
mrys@microsoft.com, rys@acm.org
We store the Web and more...


> -----Original Message-----
> From: Jonathan Borden [mailto:jborden@mediaone.net]
> Sent: Wednesday, October 18, 2000 3:26 PM
> To: Thomas B. Passin; xml-dev@lists.xml.org
> Subject: RDF/XML, Node vs. Edge labeled graphs was: Re: Services-based
> automation
> 
> 
> Thomas B. Passin wrote:
> > Jonathan Borden wrote -
> >
> > >
> > > The XML model defines a node labelled directed graph. In
> > this model, arcs or
> > > edges have the type "element" "attribute" "CDATA section"
> > "comment" etc.
> > >
> > > The RDF model defines an edge labelled directed graph, for
> > example arcs may
> > > be labelled "color", "type.of.cheese" "type.of.sauce"
> > "topping".
> 
> >
> > Do the two models really represent anything different? Not
> > really.  But if connections - a form of structure - are the
> > most important thing to you, edge-labeled models might seem
> > more attractive or "natural".
> 
> Right, so a starter for RDF is that the edge labelled model 
> (i.e. triples),
> layered on top of XMLs node labelled model (e.g. 
> DOM,SAX,Infoset) , is a
> more 'natural' way to represent semantic information.
> 
> But we can extract RDF from colloquial XML and serialize RDF as XML by
> defining a mapping between the two representations.
> 
> I've written an XSLT RDF extractor for arbitrary XML
> http://www.openhealth.org/RDF/rdfExtractify.xsl which results 
> in a series of
> rdf:Statement's i.e. a triple (predicate,subject,object). A 
> predicate is a
> URI which names the edge (i.e. an xlink:arcrole), a subject 
> is a URI which
> names the "from" node and the object is either a URI which 
> names the "to"
> node or a string which is a value. This extractor implements 
> the "Harvesting
> RDF Statements from XLink" note http://www.w3.org/TR/xlink2rdf/ .
> 
> One of the properties of 'flattening' or reifying a piece of XML into
> triples is that a set of triples neatly fits into a 
> relational table. R.V.
> Guha has written an RDF database which operates on such triples
> (http://web.guha.com/rdfdb/) and includes a SQL like query language.
> 
> Jonathan Borden
> The Open Healthcare Group
> http://www.openhealth.org
> 
>