dr. bhavani thuraisingham
DESCRIPTION
Building Trustworthy Semantic Webs Unit #1: Introduction to The Semantic Web. Dr. Bhavani Thuraisingham. August 2006. Objective of the Unit. This unit will provide an overview of the semantic web and discuss the information management technologies for the semantic web - PowerPoint PPT PresentationTRANSCRIPT
Dr. Bhavani Thuraisingham
August 2006
Building Trustworthy Semantic Webs
Unit #1: Introduction to The Semantic Web
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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
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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
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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
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Layered Architecture for Dependable Semantic Web
0 Some Challenges: Interoperability between Layers; Security and Privacy cut across all layers; Integration of Services; Composability
XML, XML Schemas
Rules/Query
Logic, Proof and TrustTRUST
OtherServicesRDF, Ontologies
URI, UNICODE
PRIVACY
0Adapted from Tim Berners Lee’s description of the Semantic Web
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Relationships between Dependability, Confidentiality, Privacy, Trust
Dependability
ConfidentialityPrivacy
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
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What is XML all about?
0 XML is needed due to the limitations of HTML and complexities of SGML
0 It is an extensible markup language specified by the W3C (World Wide Web Consortium)
0 Designed to make the interchange of structured documents over the Internet easier
0 Key to XML is Document Type Definitions (DTDs)- Defines the role of each element of text in a formal model
0 Allows users to bring multiple files together to form compound documents
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Example XML Document
Patents
Funds
Year: 2002
Name: U. Of X
ExpensesName:CS
titleAuthorID
Asset report
Assets
Dept
Equipment
news
Patent
Other assets
Grants
Contracts
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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>
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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
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RDF
0 Resource Description Framework is the essence of the semantic web
0 Adds semantics with the use of ontologies, XML syntax0 RDF Concepts
- Basic Model =Resources, Properties and Statements
- Container Model=Bag, Sequence and Alternative
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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)
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Rules Processing
User Interface Manager
ConstraintManager
Rules/ Constraints
Query Processor:
Constraints during query and release operations
Update Processor:
Constraints during update operation
XML Database Design Tool
Constraints during database design operation
XMLDatabase
XML DocumentManager
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Rule-Processing (Concluded)
Policies
Ontologies
Rules
Semantic Web Engine
XML, RDF DocumentsWeb Pages, Databases
Inference Engine/Rules Processor
Interface to the Semantic WebTechnologyBy W3C
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Semantic Web Database Management0 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
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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
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Web service architecture
Service requestor
Service providers
UDDI
PublishQuery
Answer
Request the service
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Secure Web Service Architecture
Confidentiality, Authenticity, IntegrityConfidentiality, Authenticity, Integrity
Service requestor
Service provider
UDDIQuery
BusinessEntity
BusinessService
BindingTemplate
<dsig:Signature>
BusinessService
tModel
PublisherAssertion
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Example Web Service
0 Publish/Subscribe Service
Broker/Matching Service
PublisherService: Findingthe Best Route
PublisherService:MaintainingSchedules
Subscription:Request the BestRoute
Subscription:RequestSchedules
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Information Integration
0 Data Integration:
- Integrate the data from the heterogeneous databases and data sources
=Challenges: Common data model, Mappings between data models, Schema integration, Semantic heterogeneity, Handling heterogeneous query models, transaction strategies, security policies, etc.
0 Information Integration
- Integrate heterogeneous information sources
0 Knowledge integration
- Integrate heterogeneous knowledge sources
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Coalition Application Testbed: A Suggestion
0 Identify Coalition
- Identify Coalition Example: A good starting point will be the Coalition experiments conduced under DARPA;s CoABS program that includes MBP (Master Battle Planner) and CAMPS (Consolidated Air Mobility Planning System) applications
- Develop scenarios and determine the roles are of the coalition partners
- Identify information to be accessed/shared and how the semantic web may be used by the coalition
0 Design Policies
- Design policies (e.g., security, privacy, trust) for the coalition when accessing information resources
0 Implement Test Bed
- Develop a test bed that uses ontologies for information integration and enforces the policies
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Vision for Dependable Semantic Web
Core Semantic Web Technologies:
Systems, Networks, Agents, AI, Machine Learning, Data Mining, Languages, Software Engineering, Information Integration
Need research to bring together the above technologies
Directions:
Security/Trust/Privacy, Integrate sensor technologies, Pervasive computing, Social impact
Domain specific semantic webs:
DoD, Intelligence, Medical, Treasury,- - -
0 Some Challenges: Secure Semantic Interoperability; Secure Information Integration; Integrating Pervasive computing and sensors