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Resource Description Framework (RDF). Presented by Igor Tatarinov. 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
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Resource Description Framework(RDF) Presented by Igor Tatarinov
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 !?
RDF Data Model • A graph! • Each statement is an edge advisor Igor Alon member leader status Piazza “student”
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
Reification • Can describe properties of an RDF statement Rdf:Statement Igor rdf:object rdf:type rdf:predicate stm1 advisor creator Zack Alon rdf:object
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!
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 !?
RDF: “Forget about the Semantic Web hooey” David Megginson, 2000 • RDF: 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