WSDL on the Semantic Web - slide "Semantic Web Languages Orientation"

RDF, the XML of the Semantic Web
- Few, but important, constraints
- A basic, extensible assertional language
RDFS, the DTD of the Semantic Web
- Weak structuring of sets of terms (taxonomy-esque)
- Class and property hierarchies
- Domain and Range constraints
- Powerful, but limited, "Web like" meta-modelling
OWL, the XML Schema of the Semantic Web
- Stronger structuring of sets of terms (ontologies)
- Everything in RDFS plus
  - Complex Class constructors (unionOf, intersectionOf)
  - Additional property features (inverse, transitive)
  - Class local property type and cardinality constraints
  - More
RuleML (or future W3C rules language), the SVG
- Especially, for the Policy level
  - "Policy for Web services consists of facts, or assertions, and rules that apply to a particular Web service."
- Interchange rule syntax and ontology