Collection of general data mining briefings - PowerPoint PPT Presentation

1 / 34
About This Presentation
Title:

Collection of general data mining briefings

Description:

xmlns:rdf='http://www.w3.org/1999/02/22-rdf-syntax-ns ... Content-based constraint: If document contains information about X, then it is private ... – PowerPoint PPT presentation

Number of Views:20
Avg rating:3.0/5.0
Slides: 35
Provided by: chrisc8
Category:

less

Transcript and Presenter's Notes

Title: Collection of general data mining briefings


1
Building Trustworthy Semantic Webs Lecture 9
RDF and RDF Security
Dr. Bhavani Thuraisingham
September 24, 2008

2
Objective of the Unit
  • This unit will provide an overview of RDF and
    then discuss some security issues

3
Outline of the Unit
  • Why RDF?
  • What is RDF?
  • RDF Specifications
  • RDF Schema (RFDS)
  • RDF Axiomatic Semantics and Inferencing
  • RQL
  • Policies in RDF
  • Summary and Directions
  • Examples throughout the lecture

4
Why RDF?
  • XML cannot be used to specify semantics
  • Example
  • Professor is a subclass of Academic Staff
  • Professor inherits all properties of Academic
    Staff
  • RDF was specified so that the inadequacies of XML
    could be handled
  • RDF uses XML Syntax
  • Additional constructs are needed for RDF

5
RDF
  • Resource Description Framework is the essence of
    the semantic web
  • Adds semantics with the use of ontologies, XML
    syntax
  • RDF Concepts
  • Basic Model
  • Resources, Properties and Statements
  • Container Model
  • Bag, Sequence and Alternative

6
RDF Basics
  • Resource Everything is a resource
  • Person, Vehicle, etc.
  • Property properties describe relationships
    between resources
  • E.g., Invented
  • Statement (Object, Property, Value) Triple
  • Berners Lee invented the Semantic Web

7
RDF Specification
ltrdf RDF xmlns rdf http//w3c.org/1999/
02-22-rdf-syntax-ns xmlns xsd http//
- - - xmlns uni http// - - - - ltrdf
Description rdf about 949352 ltuni name
Berners Leelt/uninamegt ltuni titlegt
Professor lt unititlegt lt/rdf Descriptiongt ltrdf
Description rdf about ZZZ lt uni booknamegt
semantic web ltunibooknamegt lt uni authoredby
Berners Lee ltuniauthoredbygt lt/rdf
Descriptiongt lt/rdf RDFgt
8
Example
  • The following example illustrates a part of an
    RDF document describing books Building_Trustworth
    y_Semantic_Webs and Managing_and_Mining_Multimedia
    _Databases. They belong to Class Book and have
    properties author, publisher, year and ISBN.
  • lt?xml version"1.0"?gt
  • ltrdfRDF
  • xmlnsbook"http//www.example.com/book"
  • xmlnsowl"http//www.w3.org/2002/07/owl"
  • xmlnsrdf"http//www.w3.org/1999/02/22-rdf-syntax
    -ns"
  • xmlnsrdfs"http//www.w3.org/2000/01/rdf-schema"
    gt
  • ltbookBook rdfID"Building_Trustworthy_Semantic_W
    ebs"gt
  • ltbookauthorgtBhavani Thuraisinghamlt/book
    authorgt
  • ltbookpublishergtAuerbach
    Publicationslt/bookpublishergt
  • ltbookyeargt2007lt/bookyeargt

9
Example
  • ltbookISBNgt0849350808lt/bookISBNgt
  • lt/bookBookgt
  • ltbookBook rdfID"Managing_and_Mining_Multimedia_
    Databases"gt
  • ltbookauthorgtBhavani Thuraisinghamlt/bookaut
    horgt
  • ltbookpublishergtCRC Presslt/bookpublishergt
  • ltbookyeargt2001lt/bookyeargt
  • ltbookISBNgt0849300371lt/bookISBNgt
  • lt/bookBookgt
  • lt/rdfRDFgt

10
RDF Schema
  • Need RDF Schema to specify statements such as
    professor is a subclass of academic staff
  • ltrdfs Class rdf ID professor
  • ltrdfs commentgt
  • The class of Professors
  • All professors are Academic Staff Members.
  • ltrdfs commentgt
  • ltrdfs subClassof rdf resource
    academicStaffMember/gt
  • ltrdfs Classgt

11
Example
  • ltThe RDF schema for the above RDF document is as
    follows
  • lt?xml version"1.0"?gt
  • ltrdfRDF
  • xmlnsowl"http//www.w3.org/2002/07/owl"
  • xmlnsrdf"http//www.w3.org/1999/02/22-rdf-syntax
    -ns"
  • xmlnsrdfs"http//www.w3.org/2000/01/rdf-schema"
  • xmlnswsp"http//www.w3.org/2004/08/20-ws-pol-pos
    /ns"gt
  • ltrdfsClass rdfID"Book"gt
  • ltrdfscommentgtBook Classlt/rdfscommentgt
  • ltrdfssubClassOf rdfresource"http//www.w3.org/1
    999/02/22-rdf-syntax-nsResource"/gt
  • lt/rdfsClassgt

12
Example
  • ltrdfProperty rdfID"author"gt
  • ltrdfsCommentgtAuthor of the booklt/rdfsCommentgt
  • ltrdfsdomain rdfresource"Book"/gt
  • ltrdfsrange rdfresource"http//www.w3.org/1999/0
    2/22-rdf-syntax-nsLiteral"/gt
  • lt/rdfPropertygt
  • ltrdfProperty rdfID"publisher"gt
  • ltrdfsCommentgtPublisher of the booklt/rdfsCommentgt
  • ltrdfsdomain rdfresource"Book"/gt
  • ltrdfsrange rdfresource"http//www.w3.org/1999/0
    2/22-rdf-syntax-nsLiteral"/gt
  • lt/rdfPropertygt

13
Example
  • ltrdfProperty rdfID"year"gt
  • ltrdfsCommentgtYear of first publication of the
    booklt/rdfsCommentgt
  • ltrdfsdomain rdfresource"Book"/gt
  • ltrdfsrange rdfresource"http//www.w3.org/1999/0
    2/22-rdf-syntax-nsLiteral"/gt
  • lt/rdfPropertygt
  • ltrdfProperty rdfID"ISBN"gt
  • ltrdfsCommentgtISBN of the booklt/rdfsCommentgt
  • ltrdfsdomain rdfresource"Book"/gt
  • ltrdfsrange rdfresource"http//www.w3.org/1999/0
    2/22-rdf-syntax-nsLiteral"/gt
  • lt/rdfPropertygt
  • lt/rdfRDFgt

14
RDF Container Model
  • Bag Unordered container, may contain multiple
    occurrences
  • Rdf Bag
  • Seq Ordered container, may contain multiple
    occurrences
  • Rdf Seq
  • Alt a set of alternatives
  • Rdf Alt

15
RDF and Security
  • RDF specifications have been given for
    Attributes, Types Nesting, Containers, etc.
  • How can security policies be included in the
    specification
  • Example consider the statement Berners Les is
    the Author of the book Semantic Web
  • Do we allow access to the connection between
    author and book? Do we allow access to the
    connection but not to the author name and book
    name?

16
RDF Policy Specification
ltrdf RDF xmlns rdf http//w3c.org/1999/
02-22-rdf-syntax-ns xmlns xsd http//
- - - xmlns uni http// - - - - ltrdf
Description rdf about 949352 ltuni name
Berners Leelt/uninamegt ltuni titlegt
Professor lt unititlegt Level L1 lt/rdf
Descriptiongt ltrdf Description rdf about
ZZZ lt uni booknamegt semantic web
ltunibooknamegt lt uni authoredby Berners Lee
ltuniauthoredbygt Level L2 lt/rdf
Descriptiongt lt/rdf RDFgt
17
Policy Specification
  • The examples we have discussed earlier show how
    certain policies may be specified for RDF
    documents. A more detailed example is given
    below.
  • lt?xml version"1.0"?gt
  • ltrdfRDF
  • xmlnsbook"http//www.example.com/book"
  • xmlnsowl"http//www.w3.org/2002/07/owl"
  • xmlnsrdf"http//www.w3.org/1999/02/22-rdf-syntax
    -ns"
  • xmlnsrdfs"http//www.w3.org/2000/01/rdf-schema"
    gt
  • ltbookBook rdfID"Building_Trustworthy_Semantic_W
    ebs"gt
  • ltbookauthorgtBhavani Thuraisinghamlt/bookauthorgt
  • Level Secret
  • ltbookpublishergtAuerbach Publicationslt/bookpublis
    hergt
  • Level Confidential

18
Policy Specification
  • ltbookyeargt2007lt/bookyeargt
  • Level Unclassified
  • ltbookISBNgt0849350808lt/bookISBNgt
  • Level Confidential
  • lt/bookBookgt
  • ltbookBook rdfID"Managing_and_Mining_Multimedia_
    Databases"gt
  • Level Confidential
  • ltbookauthorgtBhavani Thuraisinghamlt/bookauthorgt
  • Level Secret
  • ltbookpublishergtCRC Presslt/bookpublishergt
  • Level Unclassified

19
Policy Specification
  • ltbookyeargt2001lt/bookyeargt
  • Level Unclassified
  • ltbookISBNgt0849300371lt/bookISBNgt
  • Level Unclassified
  • lt/bookBookgt
  • lt/rdfRDFgt

20
RDF Schema Security Policies
  • How can security policies be specified?
  • ltrdfs Class rdf ID professor
  • ltrdfs commentgt
  • The class of Professors
  • All professors are Academic Staff Members.
  • ltrdfs commentgt
  • ltrdfs subClassof rdf resource
    academicStaffMember/gt
  • Level L
  • ltrdfs Classgt

21
RDF Axiomatic Semantics
  • First order logic to specify formulas and
    inferencing
  • Built in functions (First) and predicates (Type)
  • Modus Ponens
  • From A and If A then B, deduce B
  • Example All containers are Resources
  • Type(?C, Container) ? Type(?c, Resource)
  • If we have Type(A, Container) then we can infer
    (Type A, Resource)

22
RDF Inferencing
  • While first order logic provides a proof system,
    it will be computationally infeasible
  • As a result horn clause logic was developed for
    logic programming this is still computationally
    expensive
  • RDF uses If then Rules
  • IF E contains the triples (?u, rdfs subClassof,
    ?v)
  • and (?v, rdfs subClassof ?w)
  • THEN
  • E also contains the triple (?u, rdfs subClassOf,
    ?w)
  • That is, if u is a subclass of v, and v is a
    subclass of w, then u is a subclass of w

23
RDF Query
  • One can query RDF using XML, but this will be
    very difficult as RDF is much richer than XML
  • Is there an analogy between say XQuery and a
    query language for RDF?
  • RQL an SQL-like language has been developed for
    RDF
  • Select from RDF document where some condition

24
Policies in RDF
  • How can policies be specified?
  • Should policies be specified as shown in the
    examples, extensions to RDF syntax?
  • Should policies be specified as RDF documents?
  • Is there an analogy to XPath expressions for RDF
    policies?
  • ltpolicy-spec cred-expr //Professordepartment
    CS target annual_ report.xml
    path //Patent_at_Dept CS//Node() priv
    VIEW/gt

25
Example Policies
  • Temporal Access Control
  • After 1/1/05, only doctors have access to medical
    records
  • Role-based Access Control
  • Manager has access to salary information
  • Project leader has access to project budgets, but
    he does not have access to salary information
  • What happens is the manager is also the project
    leader?
  • Positive and Negative Authorizations
  • John has write access to EMP
  • John does not have read access to DEPT
  • John does not have write access to Salary
    attribute in EMP
  • How are conflicts resolved?

26
Privacy Policies
  • Privacy constraints processing
  • Simple Constraint an attribute of a document is
    private
  • Content-based constraint If document contains
    information about X, then it is private
  • Association-based Constraint Two or more
    documents taken together is private individually
    each document is public
  • Release constraint After X is released Y becomes
    private
  • Augment a database system with a privacy
    controller for constraint processing

27
Policies,in RDF
  • Now, in previous examples, we have specified
    policies for RDF documents. Now, can we use RDF
    to specify policies? That is, how can RDF be used
    to specify the following policy?
  • Only those attending a class from a professor
    has read access to the lecture notes of the
    professor
  • Below we specify this policy in RDF.
  • lt/rdfRDFgt
  • xmlnsunihttp//www.w3.org/2002/07/universi
    tyonto
  • xmlnspolicy"http//www.example.com/policyo
    nto"
  • xmlnsrdf"http//www.w3.org/1999/02/22-rdf-
    syntax-ns"gt
  • ltuniLectureNotes rdfID"Data_Quality.doc"gt
  • ltuniAuthorgtBhavani Thuraisinghamlt/uniauthorgt
  • ltpolicyAccessBy rdfresourcehttp//localhost/
    bhavani/cs609/gt
  • lt/rdfRDFgt

28
Policies in RDF
  • ltrdfRDF
  • xmlnsunihttp//www.w3.org/2002/07/universit
    yonto
  • xmlnspolicy"http//www.example.com/policyon
    to"
  • xmlnsrdfhttp//www.w3.org/1999/02/22-rdf-sy
    ntax-nsgt
  • ltuniClass rdfID"cs609"gt
  • ltunitaughtyBygtBhavani Thuraisinghamlt/bookaut
    horgt
  • lt/rdfRDFgt

29
Access Control Strategy
  • Subjects request access to RDF documents under
    two modes Browsing and authoring
  • With browsing access subject can read/navigate
    documents
  • Authoring access is needed to modify, delete,
    append documents
  • Access control module checks the policy based and
    applies policy specs
  • Views of the document are created based on
    credentials and policy specs
  • In case of conflict, least access privilege rule
    is enforced
  • Works for Push/Pull modes
  • Query Modification?

30
System Architecture for Access Control
User
Pull/Query
Push/result
RDF- Access
RDF-Admin
Admin Tools
Credential base
Policy base
RDF Documents
31
RDF Databases
  • Data is presented as RDF documents
  • Query language RQL
  • Query optimization
  • Managing transactions on RDF documents
  • Metadata management RDF Schemas?
  • Access methods and index strategies
  • RDF security and integrity management

32
RDF Databases
  • select Book, NumInStock
  • from Book bookauthoredBy Author
  • . bookStock NumInStock
  • Where Author Like Bhavani
  • using namespace
  • book http//www.example.com/book
  • The requestor does not have access to the number
    of book copies in the stock. Therefore, new
    modified Query
  • select Book
  • from Book bookauthoredBy Author
  • Where Author Like Bhavani
  • using namespace
  • book http//www.example.com/book

33
Inference/Privacy Control
Interface to the Semantic Web
Technology By UTD
Inference Engine/ Rules Processor
Policies Ontologies Rules
RDF Documents Web Pages, Databases
RDF Database
34
Summary and Directions
  • RDF is beginning to be used
  • Very little work on RDF security
  • How can we specify the policies discussed in this
    unit in RDF?
  • How can query modification be carried out for RDF
    documents?
  • Design access control for RDF databases
Write a Comment
User Comments (0)
About PowerShow.com