The Semantic Web - Meaning and Vocabularies


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This gives an introduction to the Semantic Web and follows through with describing a vocabulary called FOAF. Future Wave Designs, is my web design and development company. While there are others that can understand the Semantic Web and have published introductory presentations about the Semantic Web, this might be of interest to persons in the Raleigh, Durham, Chapel Hill area of North Carolina that want to take advantage of these technologies.

Over a series of presentations like this, I will demonstrate why the Semantic Web is important and valuable to businesses and organizations today. The Semantic Web is the Web of the future and no one wants to be left behind when it comes to the benefits that the Semantic Web promises.

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The Semantic Web - Meaning and Vocabularies

  1. 1. Also Known as Web 3.0 The Web of Tomorrow is here today.Presented by Bruce Whealton: Future WaveDesigns: 1
  2. 2. Syntax Versus Semantics Syntax is like the rules of grammar, and how we order our words… or in terms of computers it deals with the format and structure of commands or how we give commands to a computer. Semantics deals with meaning. Presented by Bruce Whealton: Future Wave Designs: 2
  3. 3. Representing Meaning RDF: Resource Descriptive Framework  Everything is a resource  Data/Information/Knowledge is represented as triples: Subject – Predicate – Object  RDF is also a file format. An example that will be presented below is a foaf file: foaf.rdf Presented by Bruce Whealton: Future Wave Designs: 3
  4. 4. Meaning represented as triples Bruce knows Jean Person1 first_name Bruce Person1 last_name Whealton Similar to saying Person1 hasFirstName (has a first name of) Bruce Presented by Bruce Whealton: Future Wave Designs: 4
  5. 5. Address book Graph P1 Knows Jean First name Bruce Presented by Bruce Whealton: Future Wave Designs: 5
  6. 6. FOAF – Friend of a Friend A Semantic Web Vocabulary used to describe people, their activities and their relationships to one another. It is becoming very popular for people who discover this to setup and have their own FOAF profile. This vocabulary is the base from which other vocabularies are extended. So, what is a vocabulary in this context? Presented by Bruce Whealton: Future Wave Designs: 6
  7. 7. Semantic Web Vocabularies andOntologies For the Semantic Web we deal with controlled vocabularies, which define terms and how they relate to each other. We have a hierarchy of Classes which each have properties. This is where you get the triples which relate the classes to the values of these properties. Let’s take some examples… Presented by Bruce Whealton: Future Wave Designs: 7
  8. 8.  A Person “has name” “Bruce Whealton” Person is a class and “has name” is the predicate with “Bruce Whealton” being the value Presented by Bruce Whealton: Future Wave Designs: 8
  9. 9. Continuing with Vocabularies We use a vocabulary to describe concepts that relate to a specific domain, or an area of knowledge… or simply toa set of concepts. Different fields and professions have their own vocabulary. We need to define how the terms we want to use relate to one another. This is how we express meaning on the semantic web; And form Semantic Web databases – aka Triple Stores Presented by Bruce Whealton: Future Wave Designs: 9
  10. 10. Continuing with FOAF FOAF concepts are prefixed with the letters foaf. Examples: foaf:Person is a class which describes a person. foaf:name is a property foaf:Person foaf:name “Bruce Whealton” A triple Much more can be represented with this vocabulary, such as chat ids, web pages, weblogs; One of the most important things is who you know. Presented by Bruce Whealton: Future Wave Designs: 10
  11. 11. foaf:knows Using this property web crawlers can discover foaf profiles by crawling from one profile to the next. Each foaf profile will have links to the people that one knows along with links to web pages that describe those people, e.g. their foaf profile. Web crawlers follow those links… You build your network through the links within your foaf profile and the links to you in other profiles. Your foaf profile is stored in a file, typically, in RDF format which was described earlier in this presentation, i.e. foaf.rdf Presented by Bruce Whealton: Future Wave Designs: 11