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Resource Description Framework(RDF)

Presented by Igor Tatarinov

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RDF: Making Statements About Resources

RDF statement: A triplet: object property subject

Igor’s advisor is Alon

Resources: Things, people, properties!, etc Need an ID!

URI: http://www.cs.washington.edu/#Igor Everyone’s free to design their own IDs !?

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RDF Data Model

A graph! Each statement is an edge

Igor Alonadvisor

status

Piazza

leadermember

“student”

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A Relational View of RDF

RDF statement = “relationship” between 2 entities RDF graph = ER diagram

The Internet is an RDBMS! Every table has a primary key (URI) Can’t control others’ tables Can join (make an RDF statement):

Faculty(Alon), Student(Igor) @UW Can define Advisor(Alon, Igor) @UPenn

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Reification

Can describe properties of an RDF statement

stm1

Rdf:StatementIgor

advisor

Alon

rdf:typerdf:object

rdf:predicate

rdf:object Zack

creator

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RDF Syntax

RDF uses XML:<Description about=“Igor”> <advisor resource=“Alon”/> <status> graduate student </></>

RDF adds “semantics” to XML Each Description is an RDF statement

Basically defines an XML schema for RDF Any XML schema brings semantics! RDF = a standard XML schema!

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RDF Application: Dublin Core Metadata Initiative

Started in 1995 (before RDF) Goal: enable resource discovery on the Web Idea: embed special tags in HTML

15 standard “elements” (properties) Title, Subject, Description, Creator, etc 5 years to define the semantics!

DC defines a standard RDF Schema 15 “standard” RDF properties A tiny standard ontology Defining a bigger standard ontology is

hopeless !?

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RDF: “Forget about the Semantic Web hooey”

David Megginson, 2000RDF: technology for exchanging serialized objects: Just like XML Preserves more semantics than XML

Can recognize objects and properties w/o an additional schema

Supports a graph data model