Resource Description Framework

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Resource Description Framework

• Doncy Augustine
• Trainee (2001-2002)
• National Centre for Science Information

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Table of Contents

• What is RDF?
• Background
• Applications
• Features
• RDF Data Model
• Basic RDF Syntax
• Schemas
• Containers
• Sharing Values
• Conclusion

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What is RDF?

• It is the Resource Description Framework-is a
  framework for metadata. It provides
  interoperability between applications that
  exchange machine-understandable information on
  the web. RDF emphasizes facilities to enable
  automated processing of web resources and as such
  provides the basic building blocks for supporting
  the Semantic Web.

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Background

• The history of metadata at the W3C began in 1995
  with PICS. PICS is a mechanism for communicating
  ratings of web pages from a server to clients.
  These ratings, or rating labels, contain
  information about the content of web pages.
  Instead of being a fixed set of criteria, PICS
  introduced a general mechanism for creating
  rating systems. Through a series of meetings with
  the digital library community, limitations in the
  PICS specifications were identified.

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Background contd..

• and functional requirements were outlined to
  address the more general problem of associating
  descriptive information with Internet resources
  based on the PICS architecture. As a result, W3C
  Resource Description Framework working group has
  been developed. RDF is the result of a number of
  metadata communities bringing together their
  needs to provide a robust and flexible
  architecture for supporting metadata on the web.

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Applications

• In resource discovery to provide better search
  engine capabilities.
• In cataloguing for describing the content and
  content relationships available at a particular
  web site, page or digital library.
• To facilitate knowledge sharing and exchange.
• In content rating.
• In describing collections of pages that represent
  a single logical document.
• For describing IPR

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Features

• Interoperability of Metadata.
• Machine understandable semantics for metadata.
• Better precision in resource discovery.
• Uniform query capability for resource discovery
• Processing rules language for automated
  decision-making about web resources
• Language of retrieving metadata from third
  parties.

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RDF Data Model

• Basic RDF Model
• Resource
• Properties
• Statements Subject
• Predicate
• Object
• Example

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2. Basic RDF syntax

• RDF uses XML as a common syntax. It provides user
  extensibility, validation and the ability to
  represent complex structures.By exploiting the
  feature of XML, RDF imposes structure that
  provides the clear expression of semantics and
  enable consistent encoding, exchange and machine
  processing of standardized metadata.

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Syntax contd..

• Basic Serialization syntax
• The XML syntax has been designed to accommodate
  the several properties of a resource by grouping
  multiple statements for the same resource into a
  Description element.
• Basic Abbreviated syntax
• This allows documents obeying certain
  well-structured XML DTDs to be directly
  interpreted as RDF models.

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3. Schemas

• Schema defines the terms that will be used in RDF
  statements and gives specific meanings to them. A
  variety of schema forms can be used in RDF,
  including a specific form defined in a separate
  document that has some specific characteristics
  to help with automating tasks using RDF. It uses
  the XML namespace facility.

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Containers

• Three types of container objects
• Bag-Unordered list of resources.
• Sequence-An ordered list of resources.
• Alternative-List of resources that represent
  alternatives for the single value of a property.

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Sharing Values

• A single resource can be the value of more than
  one property that is, it can be the object of
  more than one statement and therefore pointed to
  by more than one arc.

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Sharing Value contd..

• Consider the case of specifying the collected
  works of an author, sorted once by publication
  date and sorted again alphabetically by subject
• ltRDF xmlns"http//www.w3.org/1999/02/22-rdf-synta
  x-ns"gt ltSeq ID"JSPapersByDate"gt ltli
  resource"http//www.dogworld.com/Aug96.doc"/gt
  ltli resource"http//www.webnuts.net/Jan97.html"/gt
  ltli resource"http//www.carchat.com/Sept97.html"
  /gt lt/Seqgt ltSeq ID"JSPapersBySubj"gt ltli
  resource"http//www.carchat.com/Sept97.html"/gt
  ltli resource"http//www.dogworld.com/Aug96.doc"/gt
  ltli resource"http//www.webnuts.net/Jan97.html"/
  gt lt/Seqgt lt/RDFgt

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Conclusion

• The World Wide Web affords unprecedented access
  to distributed information. Metadata improves
  access to this information and RDF is a W3C
  proposed standard for defining the architecture
  necessary for supporting web metadata. RDF is an
  application of XML that imposes needed structural
  constraints to provide unambiguous methods of
  expressing semantics for the consistent encoding,
  exchange, and machine processing of metadata. RDF
  additionally, provides means for publishing both
  a human-readable and a machine-processable
  vocabularies designed to encourage the exchange,
  use and extension of metadata semantics among
  disparate information communities

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Thank You