[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] RE: RDF/XML, Node vs. Edge labeled graphs was: Re: Services-basedautomat
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@a... 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 > >
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