1. The Institute for Learning and Research Technology is a national centre of excellence in the development and use of technology-based methods in teaching, learning and research 1 Institute for Learning and Research Technology Understanding RDF The Resource Description Framework in Context Dan Brickley ILRT, University of Bristol daniel.brickley@bristol.ac.uk

2. The Institute for Learning and Research Technology is a national centre of excellence in the development and use of technology-based methods in teaching, learning and research 2 Institute for Learning and Research Technology Outline RDF overview (origin, aims…) target applications components of RDF –RDF data model –RDF syntax (in XML) –RDF vocabularies (schemas) current status issues and challenges

3. The Institute for Learning and Research Technology is a national centre of excellence in the development and use of technology-based methods in teaching, learning and research 3 Institute for Learning and Research Technology RDF origins W3C Metadata Activity 1997-1999 PICS (Internet content selection) Warwick Framework / Dublin Core XML (XML Data, Channels etc) MCF (Apple, Netscape) PICS-NG Working Group URI specification for Web identifiers

4. The Institute for Learning and Research Technology is a national centre of excellence in the development and use of technology-based methods in teaching, learning and research 4 Institute for Learning and Research Technology RDF - architectural aims W3C Metadata needs: PICS,Dsig, DC Defines a convention for applications that exchange metadata on the Web XML used for serialisation syntax Vocabulary semantics defined by communities of expertise, not W3C Fine-grained mixing of diverse metadata

5. The Institute for Learning and Research Technology is a national centre of excellence in the development and use of technology-based methods in teaching, learning and research 5 Institute for Learning and Research Technology What is RDF, really? Resource Description Framework Resources: things that can be named with URIs (http, urn, doi...) Description: statements about the properties of these resources Framework: a common model for diversity Builds on: URI for identifiers, XML for syntax (file format) URI: Uniform Resource Identifiers XML: Extensible Markup Language Self Describing! - a framework for describing resources...

6. The Institute for Learning and Research Technology is a national centre of excellence in the development and use of technology-based methods in teaching, learning and research 6 Institute for Learning and Research Technology Target applications resource discovery, indexing, cataloging privacy, preferences, user profiles sitemaps / web collections content rating, filtering, trust (Dsig/PICS) intellectual property rights... What can these diverse applications have in common?

7. The Institute for Learning and Research Technology is a national centre of excellence in the development and use of technology-based methods in teaching, learning and research 7 Institute for Learning and Research Technology Syntax: RDF uses XML ( What does RDF add to XML?) Extensible Markup Language A simple universal file format RDF adds interpretation rules: what does this data tell us? XML/RDF uses URIs to unambiguously name vocabularies When we see XML using the RDF syntax, we can interpret the markup as making statements about the named properties of Web resources. Even if weve never heard of that vocabulary...

8. The Institute for Learning and Research Technology is a national centre of excellence in the development and use of technology-based methods in teaching, learning and research 8 Institute for Learning and Research Technology RDF / Dublin Core example… <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:dc="http://purl.org/dc/elements/1.0/ > Joe Smith

9. The Institute for Learning and Research Technology is a national centre of excellence in the development and use of technology-based methods in teaching, learning and research 9 Institute for Learning and Research Technology RDF Model = Warwick Framework ? No single vocabulary can describe it all... Dublin Core (common discovery core) IMS Metadata (educational content) V-Card (data about people) Classification systems (thesauri etc.) Industry specific (eg. XMLNews.org) (your metadata application here…)

10. The Institute for Learning and Research Technology is a national centre of excellence in the development and use of technology-based methods in teaching, learning and research 10 Institute for Learning and Research Technology RDF data model - example

11. The Institute for Learning and Research Technology is a national centre of excellence in the development and use of technology-based methods in teaching, learning and research 11 Institute for Learning and Research Technology RDF data model: details... R1R2 Nodes are resources connected by named properties P1 R1 foo The degenerate case is an arc terminating in a fixed value P1 R1R2R3 R6R4 An RDF description consists of a directed graph of arbitrary complexity R7 R5 R8 P1P2 P3 P4 P5 P6 P7

12. The Institute for Learning and Research Technology is a national centre of excellence in the development and use of technology-based methods in teaching, learning and research 12 Institute for Learning and Research Technology RDF model: one simple idea... (the same idea that underpins the Web) The most fundamental specification of Web architecture, while one of the simpler, is that of the Universal Resource Identifier, or URI. The principle that anything, absolutely anything, on the Web should identified distinctly is core. (Tim Berners-Lee) RDF aims to build a Web of overlapping metadata vocabularies We use URIs to define metadata vocabularies We build graphs using these vocabularies to say things...

13. The Institute for Learning and Research Technology is a national centre of excellence in the development and use of technology-based methods in teaching, learning and research 13 Institute for Learning and Research Technology The common model: Why use Nodes and Arcs? Arbitrarily extensible (just add more arcs!) Node and arc model can use multiple vocabularies, distinguished by URI We can disagree about semantics, but share infrastructure (syntax, query, editors) URIs create market for data merging, aggregation, annotation and filtering services

14. The Institute for Learning and Research Technology is a national centre of excellence in the development and use of technology-based methods in teaching, learning and research 14 Institute for Learning and Research Technology RDF Schema Specification RDF schemas are Web resources (and have URIs) and can be described using RDF RDF properties (size, colour, price, creator...) describe resources and their relationships Resources are grouped into classes, which can be organised hierarchically Properties make sense in context of certain classes of Web resource, eg. sizeInBytes

15. The Institute for Learning and Research Technology is a national centre of excellence in the development and use of technology-based methods in teaching, learning and research 15 Institute for Learning and Research Technology RDF Schema: example

16. The Institute for Learning and Research Technology is a national centre of excellence in the development and use of technology-based methods in teaching, learning and research 16 Institute for Learning and Research Technology RDF Schema: extensibility properties and classes in an RDF schema have URIs Things with URIs can be described in RDF A foundation for mapping between vocabularies http://mymetadata.vocab.org/author --- rdfs:subPropertyOf ---> http://purl.org/dc/elements/1.0/Creator

17. The Institute for Learning and Research Technology is a national centre of excellence in the development and use of technology-based methods in teaching, learning and research 17 Institute for Learning and Research Technology Current Status Model and Syntax is now W3C Recommendation RDF Schema is a Proposed Recommendation RDF Query - likely future work Tools are becoming available...

18. The Institute for Learning and Research Technology is a national centre of excellence in the development and use of technology-based methods in teaching, learning and research 18 Institute for Learning and Research Technology Getting started… W3C Site: http://www.w3.org/RDF/ RDF-DEV developers list http://www.ilrt.bris.ac.uk/discovery/rdf-dev/ Several RDF parsers now available (Perl, Java...) Netscape / Mozilla RDF implementation http://www.mozilla.org/rdf/doc/ Applications are starting to appear...

19. The Institute for Learning and Research Technology is a national centre of excellence in the development and use of technology-based methods in teaching, learning and research 19 Institute for Learning and Research Technology For discussion... What is the URI of a person? Of a museum artifact? Of a Web site or page or alternate- language version of that page? E-commerce will require unambiguity. Progress with URIs needed - RDF alone cant fix the Web...