1. Processing of structured documents Part 8

2. 2 Resource Description Framework (RDF) zWeb was originally built for human consumption yalthough everything is machine-readable, the data is not (usually) machine-understandable yit is hard to automate anything on the web, but it is also not possible to manage the data manually zSolution: metadata (”data about data”)

3. 3 RDF zA framework that provides interoperability between applications zemphasizes facilities to enable automated processing of Web resources

4. 4 RDF: application areas zresource discovery zcataloging zintelligent software agents zcontent rating zdescribing collections of pages zdescribing intellectual property rights zexpressing privacy preferences

5. 5 RDF: application areas zprofiles ydevices, connections: CC/PP ypersons yservices zcombined with digital signatures

6. 6 RDF zRDF Model and Syntax Specification, Feb 1999 zRDF Schema Specification, Mar 2000

7. 7 Basic RDF model zA model for representing named properties and property values zthree object types yresources yproperties ystatements

8. 8 Basic RDF model zResources yall things being described are called resources ymay be a web page, a part of a web page, a collection of pages, an object that is not directly accessible via the web (e.g. a printed book) yresources are always named by URIs xanyting can have a URI

9. 9 Basic RDF model zProperties ya property is a specific aspect, characteristic, attribute, or relation used to describe a resource yeach property has a specific meaning, defines its permitted values, the types of resources it can describe, and its relationship with other properties ybasic model does not address how the characteristics of properties are expressed

10. 10 Basic RDF model zStatements ya specific resource together with a named property + the value of that property for that resource is an RDF statement ythree parts: subject, predicate, object ythe object can be another resource or a literal

11. 11 Examples zOra Lassila is the creator of the resource http://www.w3.org/Home/Lassila. zThis sentence has the following parts: ysubject (resource): http://www.w3.org/… ypredicate (property): Creator yobject (literal): ”Ora Lassila”

12. 12 Graph

13. 13 Example zThe individual whose name is Ora Lassila, email, is the creator of http://www.w3.org/Home/Lassila. zNow the creator is represented as another resource ythe resource is anonymous

14. 14 Graph

15. 15 Example zThe individual referred to by employee id 85740 is named Ora Lassila and has the email address lassila@w3.org. The resource http://www.w3.org/Home/Lassila was created by this individual. zAssume the URIs that serve as unique keys of employees might be like yhttp://www.w3.org/staffId/85740

16. 16 Graph

17. 17 Basic XML syntax zThe RDF data model provides an abstract, conceptual framework for defining and using metadata za concrete syntax is also needed ycreating and exchanging metadata zXML can be used for encoding RDF

18. 18 Example, full serialization syntax <rdf:RDF xmlns:rdf=”http://www.w3.org/1999/02/22-rdf-syntax-ns#” xmlns:s=”http://example.org/schema”> Ora Lassila

19. 19 Example, full serialization syntax <rdf:RDF xmlns:rdf=”http://www.w3.org/1999/02/22-rdf-syntax-ns#” xmlns:s=”http://example.org/schema” xmlns:v=”http://person.org/schema” > ”Ora Lassila” ”lassila@w3.org”

20. 20 Example: abbreviated syntax <rdf:RDF xmlns:rdf=”http://www.w3.org/1999/02/22-rdf-syntax-ns#” xmlns:s=”http://example.org/schema” xmlns:v=”http://person.org/schema” > <s:Creator rdf:resource =”http://www.w3.org/staffId/85740” v:Name=”Ora Lassila” v:Email=”lassila@w3.org” />

21. 21 RDF Schemas zThe RDF model does not define the vocabulary for properties, constraints of resources, etc. zresource description communities require the ability to say certain things about certain kinds of resources yfor describing bibliographic resources: ”author”, ”title”, ”subject”,...

22. 22 RDF Schemas zThe declaration of these properties and their corresponding semantics are defined as an RDF Schema zthe RDF schema specification language provides a basic type system yit defines properties and resources such as rdfs:Class and rdfs:subClassOf that are used in specifying application-specific schemas yRDF schemas are also RDF documents

23. 23 Semantic web zSemantics of resources (data, services,…) are described using RDF (or something like that znew information can be inferred using the semantic metadata (reasoning)