resource description framework (rdf) presented by: jonathan catlett
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Resource Description Framework (RDF)Presented by:Jonathan Catlett
Presentation TopicsBackgroundOverviewExampleWhat is RDF?HistorySyntaxConclusion
BackgroundMetadataStructured data about dataUsed by clients (web browsers) to improve discovery and access of distributed information.Usually imbedded into HTML to tell the browser what information is contained in the page.
BackgroundOntologyDescribes the structure of information at different levels of abstraction.A tree-like structure which can be used to describe semantics.Parse treesFor this presentation we will use an ontology only to describe the hierarchy of the resources or information.
OverviewThe Resource Description Framework is an infrastructure that enables the exchange of metadata structured in an ontology.Let us show this using an example!
Example!Lets say there is a document server and a client that would like a list of the documents.Very simple example.We will see sample syntax later.
Another Example!What about a server that maintains bookmarks instead of documents?Pretty simple!Now what if one of the bookmarks is a link to a script that will list all of the clients current email on the server?Then the structure gets more complex and dynamic.This is where the RDFs ability to handle the ontology is needed.
What is RDF?Developed by the World Wide Web Consortium (W3C) to provide a standard for defining an architecture for supporting the vast amount of web metadata.Implemented using XML!Since it is an application of XML, it inherits the syntax from XML.Namespaces for example.
What is RDF?Human and machine readableMachine-readable just means that it maintains the structure of the ontology.This is very important.
What is RDF?For example, the following two sentences mean the same thing to a human, but are very different to a machine.The author of Document 1 is John SmithJohn Smith is the author of Document 1RDF maintains the semantics and is unambiguous.
What is the RDF Data Model?This is how the data is represented using XML.A Resource is any object identifiable by a URI.The properties associated with a resource are property-types.Each property-type has a value.A collection of property-types for the same resource is called a Description.
RDF Data Model Diagram
What is the RDF Data Model?These Descriptions are kept unambiguous using the XML syntax and namespaces.Property-types may also contain collections of valuesBags Simple collectionSequence Order mattersAlternative If-then type structure.
HistoryHow did this all come about you may ask.Metadata began in 1995 with PICS.Platform for Internet Content Selection (PICS)Mechanism for communicating ratings of web pages from server to clients.Content controlIntroduced a general mechanism for creating rating system.No fixed set of criteria.
HistoryW3C started thinking about the general problem of Interned resource description based on the PICS architecture.W3C formed the PICS-NG (Next Generation) working group.This eventually led to the development of the Resource Description Framework (RDF)
SyntaxSimple document report
The Future of Metadata Jacky Crystal 1998-01-01 Metadata, RDF, Dublin Core
SyntaxComplex Value... Dr Jacky J Crystal Director email@example.com Researcher
SyntaxBag... Maddie Azzurii Corky Brown Jacky Crystal
SyntaxSequence... Maddie Azzurii Corky Brown Jacky Crystal
SyntaxAlternative... Programmer Programmeur Programmatore
Title The name given to the resource, usually by the Creator or Publisher
Author or Creator The person or organisation primarily responsible for the intellectual content of the resource
ConclusionRDF provides a needed standard for describing resources between client and server.The next step is to get organizations to use the RDF instead of proprietary resource descriptions.The increasing popularity of XML and JAVA should help the acceptance of RDF.
ResourcesAn Introduction to the Resource Description Frameworkwww.dlib.org/dlib/may98/miller/05miller.htmlAn Idiots Guide to the Resource Description Frameworkwww.dstc.edu.au/Research/Projects/rdf/RDF-Idiot.htmlRDF: In Fifty Words or Lesswww.mozilla.org/rdf/50-words.html