OutlineFrom Today’s Web to Semantic webKnowledge Management and Personal AgentsE-CommerceSemantic Web TechnologiesLayered Approach: Tim Berners Lee’s Vision www.w3c.orgWhat is XML all about?XML ElementsSlide 10Slide 11Slide 12XML AttributesXML DTDXML SchemaXML NamespacesSlide 17Federations/DistributionCredentials in XMLPolicies in XMLAccess Control StrategySystem Architecture for Access ControlThird-Party ArchitectureXML DatabasesInference/Privacy ControlWhy RDF?RDFRDF BasicsRDF Container ModelRDF SpecificationSlide 31RDF Policy SpecificationRDF SchemaRDF Schema: Security PoliciesRDF Axiomatic SemanticsRDF InferencingRDF QueryPolicies in RDFOntologyWhy RDF is not sufficient?Security and OntologyOWL: BackgroundOWL FeaturesOWL Specification (e.g., Classes)OWL Specification (e.g., Property)OWL Specification (e.g., Property Restriction)Policies in OWLPolicies in OWL: ExampleLogic and InferenceWhy Rules?Example RulesMonotonic RulesLogic ProgrammingNonmonotonic RulesRule MarkupPolicies in RuleMLAn Application: Horizontal Information Products at ElsevierHorizontal Information Products at ElsevierCommon Threads and ChallengesDr. Bhavani ThuraisinghamThe University of Texas at DallasTrustworthy Semantic WebsOctober 28, 2009Data and Applications Security Developments and DirectionsOutlineSemantic webXML and XML securityRDF and RDF securityOntologiesRulesApplicationsReference:-Building trustworthy semantic web, Thuraisingham, CRC Press, 2007From Today’s Web to Semantic webToday’s web-High recall, low precision: Too many web pages resulting in searches, many not relevant-Sometimes low recall-Results sensitive to vocabulary: Different words even if they mean the same thing do not results in same web pages-Results are single web pages not linked web pagesSemantic web-Machine understandable web pages-Activities on the web such as searching with little or no human intervention-Technologies for knowledge management, e-commerce, interoperability-Solutions to the problems faced by today’s webKnowledge Management and Personal AgentsKnowledge Management-Corporation Need: Searching, extracting and maintaining information, uncovering hidden dependencies, viewing information-Semantic web for knowledge management: Organizing knowledge, automated tools for maintaining knowledge, question answering, querying multiple documents, controlling access to documentsPersonal Agent-John is a president of a company. He needs to have a surgery for a serious but not a critical illness. With current web he has to check each web page for relevant information, make decisions depending on the information provided-With the semantic web, the agent will retrieve all the relevant information, synthesize the information, ask John if needed, and then present the various options and makes recommendationsE-CommerceBusiness to Consumer-Users shopping on the web; wrapper technology is used to extract information about user preferences etc. and display the products to the user-Use of semantic web: Develop software agents that can interpret privacy requirements, pricing and product information and display timely and correct information to the use; also provides information about the reputation of shopsBusiness to Business-Organizations work together and carrying out transactions such as collaborating on a product, supply chains etc. With today’s web lack of standards for data exchange-Use of semantic web: XML is a big improvement, but need to agree on vocabulary. Future will be the use of ontologies to agree on meanings and interpretationsSemantic Web TechnologiesExplicit metadata:-Metadata is data about data; Need metadata to be explicitly specified so that different groups and organizations will know what is on the web-Metadata specification languages include XML and RDFOntologies-Explicit and formal specification of conceptualization describes a domain of discourse; relationships-Ontology languages include XML, RDF, OWL Logic-Logic can be used to specify facts as well as rules; New facts and derived from existing facts based on the inference rules-Descriptive Logic is the type of logic that has been developed for semantic web applicationsLayered Approach: Tim Berners Lee’s Visionwww.w3c.orgWhat is XML all about?XML is needed due to the limitations of HTML and complexities of SGMLIt is an extensible markup language specified by the W3C (World Wide Web Consortium)Designed to make the interchange of structured documents over the Internet easierKey to XML used to be Document Type Definitions (DTDs)-Defines the role of each element of text in a formal modelXML schemas have now become critical to specify the structure-XML schemas are also XML documentsXML ElementsXML StatementJohn Smith is a Professor in TexasThis can be expressed as follows:<Professor><name> John Smith </name><state> Texas </state></Professor>XML ElementsNow suppose this data can be read by anyone then we can augment the XML statement by an additional element called access as follows.<Professor><name> John Smith </name><state> Texas </state><access> All, Read </access></Professor>XML ElementsIf only HR can update this XML statement, then we have the following:<Professor><name> John Smith </name><state> Texas </state><access> HR department, Write </access></Professor>XML ElementsWe may not wish for everyone to know that John Smith is a professor, but we can give out the information that this professor is in Texas. This can be expressed as:<Professor><name> John Smith, Govt-official, Read </name><state> Texas, All, Read </state><access> HR department, Write </access></Professor>XML AttributesSuppose we want to specify to access based on attribute values. One way to specify such access is given below.<ProfessorName = “John Smith”, Access = All, ReadSalary = “60K”, Access = Administrator, Read, WriteDepartment = “Security” Access = All, Read</ProfessorHere we assume that everyone can read the name John Smith and Department Security. But only the administrator can read and write the salary attribute.XML DTDDTDs essentially specify the structure of XML documents. Consider the following DTD for Professor with elements Name and State. This will be specified as:<!ELEMENT Professor Officer (Name, State)><!ELEMENT name (#PCDATA)><!ELEMENR state (#PCDATA)><!ELEMENT access (#PCDATA).>XML SchemaWhile DTDs were the early attempts to specify structure for XML documents, XML schemas are far more
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