Building Trustworthy Semantic Webs Unit 1 Introduction to The Semantic Web Dr Bhavani Thuraisingham August 2006 01 14 19 06 05 12 2 Objective of the Unit 0 This unit will provide an overview of the semantic web and discuss the information management technologies for the semantic web 0 Reference XML Databases and the Semantic Web CRC Press Thuraisingham March 2002 01 14 19 06 05 12 3 Outline of the Unit 0 Semantic Web Overview 0 Web Data Management and Web Services 0 XML eXtensible Markup Language 0 RDF Resource Description Framework 0 Information Integration and Ontologies 0 Rules Processing 0 Coalition Testbed Suggestion 0 Directions 01 14 19 06 05 12 4 Semantic Web Overview 0 According to Tim Berners Lee The Semantic Web supports Machine readable and understandable web pages Enterprise application integration Nodes and links that essentially form a very large database Premise Semantic Web Technologies XML RDF Ontologies Rules Applications Web Database Management Web Services Information Integration 01 14 19 06 05 12 5 Layered Architecture for Dependable Semantic Web 0Adapted from Tim Berners Lee s description of the Semantic Web T R U S T P R I V A C Y Logic Proof and Trust Rules Query RDF Ontologies Other Services XML XML Schemas URI UNICODE 0 Some Challenges Interoperability between Layers Security and Privacy cut across all layers Integration of Services Composability 01 14 19 06 05 12 6 Relationships between Dependability Confidentiality Privacy Trust Privacy Confidentiality Dependability Trust Dependability Security Privacy Trust Real time Processing Fault Tolerance also sometimes referred to as Trustworthiness Confidentiality Preventing the release of unauthorized information considered sensitive Privacy Preventing the release of unauthorized information about individuals considered sensitive Trust Confidence one has that an individual will give him her correct information or an individual will protect sensitive information 01 14 19 06 05 12 7 What is XML all about 0 XML is needed due to the limitations of HTML and 0 0 0 0 complexities of SGML It is an extensible markup language specified by the W3C World Wide Web Consortium Designed to make the interchange of structured documents over the Internet easier Key to XML is Document Type Definitions DTDs Defines the role of each element of text in a formal model Allows users to bring multiple files together to form compound documents 01 14 19 06 05 12 8 Example XML Document Year 2002 Asset report Assets Dept Patents Name U Of X Equipment Other assets Funds Patent news Name Expenses CS Contracts Grants ID Author title 01 14 19 06 05 12 9 Specifying User Credentials in XML Professor credID 9 subID 16 CIssuer 2 name Alice Brown name university University of X university department CS department research group Security research group Professor Secretary credID 12 subID 4 CIssuer 2 name John James name university University of X university department CS department level Senior level Secretary 01 14 19 06 05 12 10 Specifying Security Policies in XML Xml VERSION 1 0 ENCODING utf 8 Policy base policy spec cred expr Professor department CS target annual report xml path Patent Dept CS Node priv VIEW policy spec cred expr Professor department CS target annual report xml path Patent Dept EE Short descr Node and Patent Dept EE authors priv VIEW policy spec cred expr policy spec cred expr Policy base Explantaion CS professors are entitled to access all the patents of their department They are entitled to see only the short descriptions and authors of patents of the EE department 01 14 19 06 05 12 11 RDF 0 Resource Description Framework is the essence of the semantic web 0 Adds semantics with the use of ontologies XML syntax 0 RDF Concepts Basic Model Resources Properties and Statements Container Model Bag Sequence and Alternative 01 14 19 06 05 12 12 Ontology Mappings 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 including RDF and OIL Ontology Interface Language 01 14 19 06 05 12 13 Rules Processing User Interface Manager Rules Constraints Constraint Manager Query Processor Constraints during query and release operations Update Processor XML Database Design Tool Constraints during database design operation Constraints during update operation XML Document Manager XML Database 01 14 19 06 05 12 14 Rule Processing Concluded Technology By W3C Interface to the Semantic Web Inference Engine Rules Processor Policies Ontologies Rules Semantic Web Engine XML RDF Documents Web Pages Databases 01 14 19 06 05 12 15 Semantic Web Database Management 0 Database access through the semantic web XML RDF technologies 0 Query indexing and transaction management for web databases E g New kinds of transaction models for E commerce applications Index strategies for unstructured data 0 Query languages and data models XML has become the standard document interchange language 0 Managing XML RDF databases on the web XML QL Extensions to XML Query and Indexing strategies 01 14 19 06 05 12 16 Web Services 0 Web Services are about services on the web for carrying out many functions including directory management source location subscribe and publish etc 0 Web services description language WSDL exists for web services specification 0 Web services architectures have been developed 0 Challenge now is to compose web services how do you integrate multiple web services and provide composed web service in a seamless fashion 0 Ultimate goal is to have web services for information integration 01 14 19 06 05 12 17 Web service architecture Query Publish UDDI Answer Service requestor Request the service Service providers 01 14 19 06 05 12 18 Secure Web Service Architecture Confidentiality Authenticity Integrity BusinessEntity dsig Signature Query BusinessService UDDI PublisherAssertion BusinessService Service requestor tModel Service provider BindingTemplate 01 14 19 06 05 12 19 Example Web Service 0 Publish Subscribe Service Publisher Service Finding the Best Route Publisher Service Maintaining Schedules Broker Matching Service Subscription Request the Best Route Subscription Request Schedules 01 14 19 06 05 12 20 Information Integration 0 Data Integration Integrate the data from the heterogeneous databases and data sources Challenges Common data