It’s all semantics! The premises and promises of the semantic web .

It’s all semantics!The premises and promises of the semantic web. Tony Ross Centre for Digital Library Research, University of Strathclyde Email: anthony.ross@strath.ac.uk

What is the Semantic Web? “The Semantic Web is not a separate Web but an extension of the current one, in which information is given well-defined meaning, better enabling computers and people to work in co-operation.” (Berners-Lee et al., 2001) “There is realization now, ‘It's not the documents, it is the things they are about which are important’. Obvious, really.” (Berners-Lee, 2007)

The Semantic Web: basic ideas [1] • The Web evolved largely as a platform for the linking and sharing of documents. • Simplicity was key. • A largely syntactic rather than semantic framework. • Hence browsers display data without actually being aware of its ‘meaning’.

The Semantic Web: basic ideas [2] • Currently, intermediate programmes must be built to allow interoperability between specific programmes. • E.g. Insurance price comparison sites • Web data is controlled by applications; the structure and format of that data is therefore particular rather than universal. • Wouldn’t it be better if machines were able to interpret and process the content of documents?

The Semantic Web: basic ideas [3] • But, this will require a lot of metadata and a lot of accompanying mark up! • Plus a lot of common infrastructural services and standards of application …

Building a common framework • It’s the same old problem for cataloguing and indexing, i.e.: We need to ensure we are describing things in the same way! • We must register (and thus control): vocabularies; services; names, etc. • And construct (and agree upon) common frameworks for the way such metadata is to be applied.

The NSDL Metadata Registry Aims to make possible: • “the unambiguous identification of metadata schemas (attribute spaces or element/property sets) and schemes (value spaces or controlled vocabularies); • the machine declaration for encoding those schemes and schemas; and • the publication of those schemes and schemas to communities and applications” (Hillmann et al, 2006)

Metadata Registries • Provide a common, openly-accessible site for the registration of metadata schema. • Thus, a locally produced vocabulary – e.g. JISC IE Vocabulary – is remotely accessible to all. • This means it can be referred to and reused both within JISC and across communities. • Promotes interoperability!

eXtensible Markup Language (XML) • Enables users to annotate (markup) documents with their own locally-defined elements. • The document then points to a location for the declaration of schema format – a namespace • Other users and other documents can then use these elements and point to the namespace

Resource Description Framework (RDF) [1] • Official W3C recommendation • Published 2004 • Result of work by the RDF Core Working Group

Resource Description Framework (RDF) [2] • A framework to allow commonly interpretable specifications of relations • Simple logical assertions based on: {subject} {predicate} {object} e.g. {Document A} {has title} {“Romeo and Juliet”} • Thus, semantic metadata can be attached to a document (as XML). The ‘meaning’ of a document becomes machine processable.

Resource Description Framework (RDF) [3] • RDF doesn’t itself specify attributes or vocabularies – it is an enabling framework • Hence it can be used in conjunction with emergent standards such as RDFS, OWL, FOAF, SKOS, Dublin Core.

Simple Knowledge Organisation Systems (SKOS) [1] • Has W3C Working Draft status • SKOS-Core Guide published 2005 • Developed to allow expression of the basic structure of controlled vocabularies (thesauri, classification schemes, subject heading lists, taxonomies, ‘folksonomies’, etc.)

Simple Knowledge Organisation Systems (SKOS) [2] • Divides (5) classes of resources: • skos:ConceptScheme • skos:Concept • And sub-divides (26) properties of that class: • skos:Preflabel • skos:Broader

Demonstration • The JISC Information Environment vocabulary, developed in support of CDLR project Resource Discovery iKit • As declared using the NSDL Metadata Registry

JISC Information Environment

Persistence: the responsibilities of ownership • In order for this to work, we need stable indicators reliably pointing to resources. • The responsibilities of ownership: who will assume responsibility for issues such as persistence, security, version control – funding becomes an issue (especially as project-funding dries up). • DDC has OCLC, LCSH has LoC, AAT has Getty, etc.

Metadata Registry http://www.metadataregistry.org

References • Hillmann, D., Phipps, J., Sutton, S.A. and Laundry, R. (2006). A metadata registry from the vocabularies up: the NSDL Registry project. • Berners-Lee, T., Hendler, J. and Lasilla, O. (2001).The Semantic Web. Scientific American. 284(5). • Berners-Lee, T. (2007). timbl's blog: Giant Global Graph. Posted 21st November 2007. Available: http://dig.csail.mit.edu/breadcrumbs/node/215

It’s all semantics! The premises and promises of the semantic web .