Nick, Any educational links would be appreciated.
Thanks, Alex > -----Original Message----- > From: Niclas Hedhman [mailto:[EMAIL PROTECTED] > Sent: Thursday, November 13, 2003 4:06 AM > To: [EMAIL PROTECTED] > Subject: [Quick Tutorial] Using RDF > > > Hi, gang... > > Went through a crash course in RDF (10minutes), and would like to share > the > initial impression. > > RDF is NOT XML!!! It can be represented in XML, and I'll get to that. > > RDF is about making simple statements about a resource. > > The statements are thought or primarily represented as TREEs. > The arrowed lines between the nodes in the tree are the Predicates. The > node > at the start of the line is the Subject, and at the end is the Object. > > +---------+ Predicate +--------+ > | Subject |------------->| Object | > +---------+ +--------+ > > also known as a "Triple". For instance, I could say; > > http://niclas.hedhman.org/repository is owned by Niclas Hedhman > > In this case, "http://niclas.hedhman.org/repository"; is the subject, "is > owned > by" is the predicate and "Niclas Hedhman" is the object. > > But RDF is smart to say that each element in the "Triple" is a URI > reference, > so it can look like this; > > +-------------------------------------+ > |http://niclas.hedhman.org/repository | > +-------------------------------------+ > | > | http://hedhman.org/semantics/owned > | > V > "Niclas Hedhman" > > "Niclas Hedhman" is string literals, and that is allowed, but by having > another URI reference there we could increasing the knowledge about the > owner. > > +-------------------------------------+ > |http://niclas.hedhman.org/repository | > +-------------------------------------+ > | > | http://hedhman.org/semantics/owned > | > V > +-----------------------------------+ > |http://hedhman.org/family/640925-1 | > +-----------------------------------+ > | | > | http://hedhman.org/semantics/fullname > | | > V | > "P�r Niclas Hedhman" | > | http://hedhman.org/semantics/birthdate > | > V > "1964-09-25" > > > And so on. > > RDF allows the use of prefixes, just like XML, to reduce the verbosity and > improve human readability. > > Let's take a quick look at how the above could be represented in XML. > > <?xml version="1.0"?> > <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"; > xmlns:hed="http://hedhman.org/semantics"; > > > > <rdf:Description rdf:about="http://niclas.hedhman.org/repository";> > <hed:owned rdf:resource="http://hedhman.org/family/640925-1"; /> > </rdf:Description> > > <rdf:Description rdf:about="http://hedhman.org/family/640925-1"; > > <hed:fullname>Niclas Hedhman</hed:fullname> > <hed:birthdate>1964-09-25</hed:birtdate> > </rdf:Description> > </rdf:RDF> > > > RDF also supports user definable datatypes and containers (collections, > sets), > but I won't touch on that here. > > An RDF schema is a description on how the statement elements can be formed > together. There is a declarative language for that, RDF Vocabulary > Description Language. It may at first feel a bit awkward that RDF is used > to > define the schema language, i.e. RDF is used to describe your RDF. (But so > is > XML Schema). > It supports quite a lot of object-oriented concepts, including > subclassing, so > it is easy to understand, but I won't go into details here. > > > So let's get on with it ;o) > > Niclas > > > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
