RDF

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What is RDF?

• RDF stands for Resource Description Framework
• RDF is a framework for describing resources on the web
  • Describing properties for shopping items, such as price and availability
  • Describing time schedules for web events
  • Describing information about web pages (content, author, created and modified date)
  • Describing content and rating for web pictures
  • Describing content for search engines
  • Describing electronic libraries
• RDF is designed to be read and understood by computers
• RDF is not designed for being displayed to people
  • RDF was designed to provide a common way to describe information so it can be read and understood by computer applications.
  • RDF descriptions are not designed to be displayed on the web.
• RDF is written in XML
  • RDF documents are written in XML. The XML language used by RDF is called RDF/XML.
  • By using XML, RDF information can easily be exchanged between different types of computers using different types of operating systems and application languages.

• RDF is a part of the W3C's Semantic Web Activity
  • W3C's "Semantic Web Vision" is a future where:
  • Web information has exact meaning
  • Web information can be understood and processed by computers
  • Computers can integrate information from the web

• RDF is a W3C Recommendation
  • RDF became a W3C Recommendation 10. February 2004.

• RDF : 웹상의 다양한 정보를 컴퓨터가 확실하게 처리할 수 있는 형태로 기술하는, 시맨틱 웹의 기본계층을 형성하는 데이터모델. 주어-술어-목적어로 구성된 트리플을 기본단위로 하고, 트리플들의 집합인 그래프에 의해 리소스를 기술.
  • 리소스란 ‘웹에서 식별할 수 있는 것’을 의미.
  • RDF는 특정한 환경을 전제로 하지 않고 처리할 수 있는 형태로 정보를 표현함.

• Concepts and Abstract Syntax에서 제시된 RDF의 설계목표 6가지
  • 단순하면서도 유연한 데이터모델
  • 논리학적인 근거가 있는 의미표현과 증명가능한 추론
  • URI를 토대로하는 확장가능한 어휘의 이용
  • XML에 의한 교환구문의 채용
  • XML스키마데이터형에 의한 데이터의 정밀한 유형화
  • 누구든지 어떠한 리소스에 대해서도 기술 가능

RDF triple : resource, property and property value

• A Resource is anything that can have a URI, such as "http://www.w3schools.com/rdf"
• A Property is a Resource that has a name, such as "author" or "homepage"
• A Property value is the value of a Property, such as "Jan Egil Refsnes" or "http://www.w3schools.com" (note that a property value can be another resource)

• RDF트리플(Triple) : 주어(Subject)-술어(Predicate)-목적어(Object) => 문장(Statement)구성
• RDF의 가장 기본적인 기술 단위. 술어를 속성(Property), 목적어를 속성값(Property Value)라고 부르기도 함.
• 주어와 목적어를 타원(노드, node)로 나타내며, 이러한 2개의 노드들을 술어를 나타내는 화살표(아크, arc)로 연결.

RDF Schema(RDFS)

• RDF Schema does not provide actual application-specific classes and properties.
• Instead RDF Schema provides the framework to describe application-specific classes and properties.
• Classes in RDF Schema are much like classes in object oriented programming languages. This allows resources to be defined as instances of classes, and subclasses of classes.