Lists Home |
Date Index |
Danny here's some free advice.
Go build some apps that kick butt.
And forget about debates.
They don't matter.
That's less than 500 words.
I bet it's less than 100.
Have a nice day.
----- Original Message -----
From: "Danny Ayers" <firstname.lastname@example.org>
To: "Xml-Dev" <email@example.com>
Sent: Saturday, November 16, 2002 9:51 AM
Subject: [xml-dev] RDF in 500 words
> There are 6 key documents in the RDF suite, and just the Primer  now
> to 89 pages of A4. To counter allegations that RDF is altogether too
> heavy/complicated/difficult/wordy, I thought I try Andrew's 500 word
> challenge on it.
> In RDF, a resource is something that can be identified on the web, and a
> description is something said about a resource.
> Resources have a universal identifier, their URI, which in the case of web
> pages will be the same as their address (URL). Pretty much anything else
> (people, places, concepts) can be identified in this way by assigning
> Descriptions are made in RDF using statements. A statement has three
> the thing being described, the characteristic of interest and the value of
> that characteristic. For example, the thing being described might be a
> say "A Christmas Carol" the characteristic of interest (property) the
> author, and the value would be the name of the author, "Charles Dickens".
> RDF jargon these three parts are the subject, predicate and object, and
> together they form a triple. The subject is a resource, the predicate is a
> special kind of resource and the object can either be another resource or
> literal text.
> As a resources, the predicates are also unambiguously identified using
> but the same predicate can be reused - when we ask who the author of a
> is, we are asking the same question whichever book we are talking about or
> whoever happens to be the author. If we want to say more about a
> book, we can use its identifier in another statement with a different
> predicate (property) and object (value). The basic nature of resources and
> predicates are defined with the help of a small set of terms in the RDF
> specifications. This set of terms allows us to give more information in
> descriptions, so we could define a classification 'paperback' and say that
> this is a kind of book. The class 'book' would in turn be described as a
> kind of resource.
> In this example we have identified the author by the text of their name,
> usually it is more useful to use a URI as that will be unambiguous, and
> allow us to say things about the author as well. So we could have another
> statement that says that this author's favourite colour is blue. Our
> knowledge can be expressed as these two statements, but as the author is a
> common feature in this we can visualise the knowledge as the three
> linked by the connection from the book to the author and from the author
> the colour blue. This structure is an example of an RDF graph. There may
> other resources that we can link in as well, like books by the same author
> or the book's publisher.
> It isn't entirely always necessary or even possible to identify
> Let's say we have identified the book and the colour blue. We can still
> two statements, "A Christmas Carol" was written by X, and the X's
> favourite colour is blue. This can still be visualised as a graph with
> items and two connections, and in the jargon X is known as a blank node.
> seeAlso: http://w3.org/RDF
>  http://www.w3.org/TR/2002/WD-rdf-primer-20021111/
> Danny Ayers
> Semantic Web Log :
> The xml-dev list is sponsored by XML.org <http://www.xml.org>, an
> initiative of OASIS <http://www.oasis-open.org>
> The list archives are at http://lists.xml.org/archives/xml-dev/
> To subscribe or unsubscribe from this list use the subscription
> manager: <http://lists.xml.org/ob/adm.pl>