It

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Its all semantics! The premises and promises of
the semantic web.

• Tony Ross
• Centre for Digital Library Research,
• University of Strathclyde
• Email anthony.ross_at_strath.ac.uk

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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)
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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.

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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.
• Wouldnt it be better if machines were able to
  interpret and process the content of documents?

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The Semantic Web basic ideas 3
Q. How can automated technologies deal with subjectivity of language (e.g. context, intention, tone, etc.) or linguistic quirks (homonymy, synonymy, etc.)? A. Only if we (humans) explicitly mark them up as such

• 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

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Building a common framework

• Its 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.

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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)

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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!

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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

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Resource Description Framework (RDF) 1

• Official W3C recommendation
• Published 2004
• Result of work by the RDF Core Working Group

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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.

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Resource Description Framework (RDF) 3

• RDF doesnt 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.

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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.)

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Simple Knowledge Organisation Systems (SKOS) 2

• Divides (5) classes of resources
• skosConceptScheme
• skosConcept
• And sub-divides (26) properties of that class
• skosPreflabel
• skosBroader

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Demonstration

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

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JISC Information Environment
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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.

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Metadata Registry

• http//www.metadataregistry.org

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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/no
  de/215