Building Trustworthy Semantic Webs Lecture 14 OWL Web Ontology Language and Security Dr Bhavani Thuraisingham February 2010 01 13 19 23 51 2 Outline of the Unit 0 What are ontologies 0 Why is RDF not sufficient 0 What are the security issues for ontologies 0 What is OWL 0 OWL Syntax and Semantics 0 Security Issues with Examples 0 Example Semantic Access Control 0 Ontology Engineering 0 Summary and Directions 01 13 19 23 51 3 Ontology 0 Common definitions for any entity person or thing 0 Several ontologies have been defined and available for use 0 Defining common ontology for an entity is a challenge 0 Mappings have to be developed for multiple ontologies 0 Specific languages have been developed for ontologies 01 13 19 23 51 4 Why RDF is not sufficient 0 RDF was developed as XML is not sufficient to specify 0 0 0 0 semantics E g class subclass relationship RDF has issues also Cannot express several other properties such as Union Interaction relationships etc Need a richer language Ontology languages were developed by the semantic web community for this purpose Essentially RDF is not sufficient to specify ontologies 01 13 19 23 51 5 Security and Ontology 0 Ontologies used to specify security policies Example OWL to specify security policies Choice between XML RDF OWL Rules ML etc 0 Security for Ontologies Access control on Ontologies Give access to certain parts of the Ontology 01 13 19 23 51 6 OWL Background 0 It s a language for ontologies and relies on RDF 0 DARPA Defense Advanced Research Projects Agency developed early language DAML DARPA Agent Markup Language 0 Europeans developed OIL Ontology Interface Language 0 DAML OIL combines both and was the starting point for OWL 0 OWL was developed by W3C 01 13 19 23 51 7 OWL Features 0 Subclass relationship 0 Class membership 0 Equivalence of classes 0 Classification 0 Consistency e g x is an instance of A A is a subclass of B x is not an instance of B 0 Three types of OWL OWL Full OWL DL OWL Lite 0 Automated tools for managing ontologies Ontology engineering 01 13 19 23 51 8 OWL Specification e g Classes owl Class rdf about associateProfessor owl disjointWith rdf resource professor owl disjointWith rdf resource assistantProfessor owl Class owl Class rdf ID faculty owl equivalentClass rdf resource academicStaffMember owl Class Faculty and Academic Staff Member are the same Associate Professor is not a professor Associate professor is not an Assistant professor 01 13 19 23 51 9 OWL Specification e g Property Courses are taught by Academic staff members owl ObjectProperty rdf about isTaughtby rdfs domain rdf resource course rdfs range rdf resource academicStaffMember rdfs subPropertyOf rdf resource involves owl ObjectProperty 01 13 19 23 51 10 OWL Specification e g Property Restriction All first year courses are taught only by professors owl Class rdf about firstyearCourse rdfs subClassOf owl Restriction owl onProperty rdf resource isTaughtBy owl allValuesFrom rdf resource Professor rdfs subClassOf owl Class 01 13 19 23 51 11 Example 0 Before we discuss security for OWL and specify policies in OWL we need to provide an example of an OWL ontology 0 The following example describes the University Ontology The different properties shown are DatatypeProperty hasCredits and ObjectProperty hasTaught isTaughtBy etc Sub properties are also shown hasCompleted is a sub property of hasRegistered The disjointWith property ensures that two classes do not have any individuals in common For example an individual from the Faculty class cannot be an individual of the Student class Using sub properties policies can be specified In the following example a faculty member can access the AnnualReports only is she he is the Dean 0 Note that OWL uses RDF and hence XML syntax Furthermore OWL has more powerful reasoning capabilities 0 The following example and subsequent security examples will make this clear 01 13 19 23 51 12 Example 0 xml version 1 0 0 DOCTYPE rdf RDF 0 ENTITY owl http www w3 org 2002 07 owl 0 ENTITY xsd http www w3 org 2001 XMLSchema 0 ENTITY rdfs http www w3 org 2000 01 rdf schema 0 ENTITY rdf http www w3 org 1999 02 22 rdf syntax ns 0 0 rdf RDF xmlns http www owl ontologies com Ontology1178660130 owl 0 xml base http www owl ontologies com Ontology1178660130 owl 0 xmlns xsd http www w3 org 2001 XMLSchema 0 xmlns rdfs http www w3 org 2000 01 rdf schema 0 xmlns rdf http www w3 org 1999 02 22 rdf syntax ns 0 xmlns owl http www w3 org 2002 07 owl 01 13 19 23 51 13 Example 0 owl Ontology rdf about 0 0 owl Class rdf ID AnnualReports rdfs subClassOf rdf resource Department 0 owl Class 0 owl ObjectProperty rdf ID canAccess 0 rdfs domain rdf resource Faculty 0 rdfs range rdf resource AnnualReports 0 rdfs subPropertyOf rdf resource isDean 0 owl ObjectProperty 0 owl Class rdf ID Course 0 rdfs subClassOf rdf resource Department 0 owl Class 0 owl Class rdf ID Department 0 owl Class rdf ID Faculty 01 13 19 23 51 14 Example 0 rdfs subClassOf rdf resource Department 0 owl disjointWith rdf resource Student 0 owl disjointWith rdf resource Staff 0 owl Class 0 owl ObjectProperty rdf ID hasCompleted 0 rdfs subPropertyOf rdf resource hasRegistered 0 owl ObjectProperty 0 owl DatatypeProperty rdf ID hasCredits 0 rdfs domain rdf resource Course 0 rdfs range rdf resource xsd int 0 owl DatatypeProperty 0 owl ObjectProperty rdf ID hasDean 0 rdfs domain 0 owl Class 01 13 19 23 51 15 Example 0 owl unionOf rdf parseType Collection 0 owl Class rdf about Course 0 owl Class rdf about Department 0 owl Class rdf about Faculty 0 owl Class rdf about Staff 0 owl Class rdf about Student 0 owl unionOf 0 owl Class 0 rdfs domain 0 rdfs range rdf resource Faculty 0 owl ObjectProperty 0 owl DatatypeProperty rdf ID hasName 0 rdfs domain 0 owl Class 01 13 19 23 51 16 Example 0 rdfs range rdf resource Faculty 0 owl ObjectProperty 0 owl DatatypeProperty rdf ID hasName 0 rdfs domain 0 owl Class 0 owl unionOf rdf parseType Collection 0 owl Class rdf about Department 0 owl Class rdf about Faculty 0 owl Class rdf about Staff 0 owl Class rdf about Student 0 owl unionOf 0 owl Class 0 rdfs domain 0 01 13 19 23 51 17 Example 0 rdfs range rdf resource xsd string 0 owl DatatypeProperty 0 owl ObjectProperty rdf ID hasPrerequisite 0 rdf type rdf resource owl TransitiveProperty 0 owl inverseOf rdf resource isPrerequisiteOf 0 owl ObjectProperty 0 owl ObjectProperty rdf ID hasRegistered 0 rdfs domain rdf resource Student 0 rdfs range rdf resource Course 0 owl ObjectProperty 0 owl ObjectProperty rdf ID