SKOS and Other W3C Vocabulary Related Activities Gail Hodge Information International Assoc. NKOS Workshop Denver, CO June 10, 2005

Acknowledgements Based on: –Presentation by Alistair Miles of the Rutherford Laboratory at the OpenForum on Metadata Registries, April –Input from Joel Sachs, Univ. of Maryland Baltimore Co. and the SPIRE Project. –Documents from the SKOS Web site.

What is the Semantic Web? Semantic Web grand vision: "The Semantic Web is an extension of the current web in which information is given well-defined meaning, better enabling computers and people to work in cooperation." … in practice: The Semantic Web provides a common technological framework (i.e. URI, RDF, SPARQL, RDFS, OWL …) that allows data to be shared and reused across application, enterprise, and community boundaries. Successful sharing and reuse requires an understanding of meaning.

Relevant W3C Semantic Web Activities Best Practices and Deployment Working Group Chartered through January 31, 2006 Working drafts: –SKOS core related documents (vocabulary specification; guide; etc.) SKOS Mapping Vocabulary API for terminology web services –XML Schema Datatypes in RDF and OWL –Defining N-ary relationships on the semantic web: Use with individuals Web Service Description Working Group 2 Chartered through January, 2006 Working Drafts –WSDL 2.0 –SOAP 1.1 Binding

Relevant Activities, contd. RDF Data Access Working Group Chartered (roughly) till end of 2005 Working Drafts: –SPARQL Query Language for RDF –SPARQL Variable Binding Results XML Format –SPARQL Protocol for RDF (written in WSDL 2.0) Web-Ontology Working Group (closed) Recommendations: –The whole OWL family of documents (language overview; language guide; language reference; use cases; etc.)

SKOS Core An extensible RDF language for describing concepts and concept schemes … … a concept scheme is a ‘set of concepts, optionally including relationships between concepts.’ … … i.e. controlled vocabularies, thesauri, classification schemes, glossaries, subject heading systems, terminologies … … e.g. AAT, DDC, AGROVOC …

OWL vs. SKOS Core OWL is the language of the Semantic Web. Why do you need SKOS if you have OWL? SKOS Core … … more flexible, less demanding approach to modelling concepts … … better suited to types of KOS mentioned … … requiring little or no remodelling to express in RDF … … therefore low cost, while adding value through simple benefits of RDF/semantic web approach.

Basic SKOS Vocabulary Skos:Concept Class (this resource is a concept) Lexical Labelling Properties (associate concept with a name) Symbolic Labelling (associate concept with symbols) Semantic Relationship Properties (relationships between concepts) Documentation Properties (definitions and change notes) Subject Indexing (connecting an information resource to terminology, dc:subject)

Traditional Thesaurus to SKOS Mapping Concept gets a URI, not a name Lexical Labeling = names (not new concepts) –Skos:prefLabel –Skos:altLabel (Used For) Relationship Labeling between concepts –Skos:broader –Skos:narrower –Skos:related Documentation such as Scope notes –Skos:scopeNote –Skos: definition

RDF Graph Representation

SKOS Status Development history –Initiated by Semantic Web Advanced Development for Europe project (SWAD-E) in 2003 –Public development process and open developer community –Driven by W3C Semantic Web Best Practices and Deployment Working Group since 2004 SKOS Core status –1 st Public Working Draft May, 2005 –RDF Vocabulary and Guidelines for KOS Conversion also available –Comments requested by end of June 2005 Standardization goal –W3C Working Group Note –W3C Recommendation track?

Open Issues: Understanding the Limitations of SKOS Difference between SKOS Core and other RDF applications because modeling concepts adds another level of indirection –Properties are properties of the concept and not necessarily of the real-world thing If two conceptual resources share the same meaning they are not necessarily the same resource –Meaning from definitions versus semantic context (relationships, labels, etc.) Concept scheme versioning – use of Skos:inScheme property HTTP URIs for Concepts (this is an open question for the Technical Architecture Group)

SKOS Resources SKOS Home Page SKOS Core Guide SKOS Core Vocabulary Quick Guide to Publishing a Thesaurus on the Semantic Web SKOS Mailing List

RDF/XML Using the UK Archival Thesaurus <rdf:RDF xmls:rdf= xmlns:rdfs= xmlns:skos= Economic cooperation Economic co-operation Includes cooperative measures in banking, trade, industry, etc. between and among countries. <skos:broader rdf:resource= 3000”> [Economic policy] skos:narrower rdf:resource= 3022”> [industrial cooperation] <skos:narrower rdf:resource= concept/3500> [Economic integration]