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Comp3503 XML and Ontologies

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Title: Comp3503 XML and Ontologies


1
Comp3503XML and Ontologies
  • Daniel L. Silver, Ph.D.

2
Outline
  • XML Fundamentals
  • XML Use
  • Ontology Fundamentals
  • Application of Ontologies
  • Ontologies and the Semantic Web

3
Problems with the HTML based Web
  • HTML documents focus on display and not structure
    and meaning of data - an information maze devoid
    of meaning
  • Inefficient use of tags - every instance of data
    must be tagged for presentation
  • Fixed number of tags - can not be extended (not
    extensible)
  • Confusing mix of standards (Netscape and IE
    innovations)
  • HTML search is based on keywords without context
  • Client-server applications cannot easily exchange
    data using HTML

4
HTML focuses on display syntax
  • HTML tags such as ltBgtSimpsonlt\Bgt tell how to
    display the word Simpson
  • Focus is on presentation (format, syntax)
  • But its does not define what Simpson means
  • A persons name? A city? A company?
  • Or its structural relationship to other data
  • Full name? Last name? First name?

5
The XML idea
  • eXtensible Markup Language
  • XML defines meaning (semantics)
    ltlnamegtSimpsonlt\lnamegt
  • In terms of structural relationships
  • Independent of presentation

ltmail_adrsgt ltfnamegtHomerlt\fnamegt
ltlnamegtSimpsonlt\lnamegt ltstrnumgt1234lt\strnumgt
ltstrgtHickup Lanelt\strgt lt\mail_adrsgt
6
What is XML?
  • 1996 - A simplified form of SGML for the web
    (Standardized General Markup Language)
  • Both machine and human readable
  • Separates content, structure and presentation
  • Extensible -users can define structure and
    meaning
  • Supports information reuse and processing
    autonomy (application decides how to use/present)

SGML
HTML
XML
7
The W3Cs 10 Design Requirements for XML
  • XML shall be easily usable over the Internet.
  • XML shall support a wide variety of applications.
  • XML shall be compatible with SGML.
  • It shall be easy to write programs that process
    XML documents.
  • The number of optional features in XML is to be
    kept to the absolute minimum, ideally zero.
  • XML documents should be human-legible (easy to
    understand).
  • The design of XML had to be done quickly
  • The design of XML shall be exact (formal) and
    concise to easy processing of the code.
  • XML documents should be easy to create.
  • Terseness (brevity) in XML markup is of minimal
    importance.

8
XML Fundamentals
lt?xml version "1.0"?gt ltcontactsgt
ltcontactgt ltLastNamegtBlacklt/LastNamegt
ltFirstNamegtJohnlt/FirstNamegt lt/contactgt
lt/contactsgt
lt!ELEMENT contacts (contact) gt lt!ELEMENT contact
(LastName, FirstName) gt lt!ELEMENT LastName
(PCDATA) gt lt!ELEMENT FirstName (PCDATA) gt
DTD Structure
Presentation in Context
XML Content
XSL Presentation
lt?xml version"1.0"?gt ltxslstylesheet xmlnsxsl
"http//www.w3.org/TR/WD-xsl"gt
9
XMLs Intended Use
  • Standard format for exchanging data
  • Promote cross-platform and cross-application
    schema independent of data content, use and
    presentation
  • Oriented toward giving meaning to data, and does
    not emphasize display issues
  • Client describes valid data for display
  • Server describes valid data for exchange

10
XMLs Intended Use
  • Allows organizations to maintain proprietary
    databases while at the same time communicate
    information with one another
  • Schemas for specific domains have been created
  • Music (MusicXML example)
  • Chemical symbols (CML)
  • Mathematical formulas (MathML)
  • Common industry models (EDI for B2B)
  • Web resource descriptions (directories,
    addresses)

11
XML versus HTML
  • XML is not a replacement for HTML
  • XML and HTML were designed with different goals
  • HTML was designed to display data and to focus on
    how data looks
  • XML was designed to describe data and to focus on
    what data means
  • They complement each other

12
XML eXtensibility
  • XML allows you to create your own definitions of
    data and there relationship to other pieces of
    data
  • Thus the name
  • eXtensible
  • Note that XML is case sensitive

lt?xml version"1.0"?gt ltPeoplegt ltPersongt
ltNamegt ltFirstgtPatricklt/Firstgt
ltLastgtJoelt/Lastgt lt/Namegt lt/Persongt lt/Peoplegt
13
Using IE to Explore XML
  • You can use Internet Explorer to view an XML
    document directly
  • A plus () or minus sign (-) to the left of the
    XML elements can be clicked to expand or collapse
    the element structure
  • Or view the raw XML source using "View Source"
    from the browser menu
  • Example cd_catalog.xml

14
Defining XML Structure
  • DTD Document Type Definition defines the fields
    in an XML document and their relation to one
    another (schema)
  • Meta-data data about data
  • Can be included in .xml file or referenced as
    a .dtd file
  • Used by applications to validate XML data

lt!ELMENT People (Person) gt lt!ELMENT Person
(Name) gt lt!ELMENT Name (First, Last) gt lt!ELMENT
First (PCDATA) gt lt!ELMENT Last (PCDATA) gt
15
Processing an XML Document
lt?xml version"1.0"?gt ltPeoplegt ltPersongt
ltNamegt ltFirstgtPatricklt/Firstgt
ltLastgtJoelt/Lastgt lt/Namegt lt/Persongt lt/Peoplegt
XML Content
  • An application that wishes to use XML
  • data should parse the data using a DTD.
  • There are two approaches
  • DOM read the entire document using the
  • DTD and build a tree of elements
  • SAX parse on demand (interactively)
  • as each new element is encountered

DOM Document Object Model SAX Simple API
for XML
16
Processing an XML Document
  • Internet Explorer 5.0 () has a built in
    DOM-based XML parser, msxml
  • DTD can be embedded in XML or referenced
  • Examples
  • simple_example.xml with DTD embedded
  • letter.xml and letter.dtd

17
Displaying XML Documents
  • Can be accomplished in various ways, any program
    that can parse the XML can display the
    information
  • Here is a simple HTML solution
  • simple_contact.html - XML is embedded, DTD is not
    required
  • Javascript could be used instead
  • article.xml and DOMexample.html
  • note.xml and note.html

18
Displaying XML Documents
  • An XSL eXtensible Stylesheet Layout can be used
  • Examples
  • Basic - contact3.xml using contact_list3.xsl
  • Full function contact.xml using
    contact_list.xsl
  • Handheld contact2.xml using contact_list2.xsl

lt?xml version"1.0"?gt ltxslstylesheet xmlnsxsl
"http//www.w3.org/TR/WD-xsl"gt
19
Transferring Data with XML
  • It is possible to use XML as a method of
    transferring meaningful data between applications
    even when application databases do not match
  • Adherence to XML DTD is the key

ODBC
JDBC
XML
App A
App B
DB2
Oracle
Common DTD
20
Smart Searches on the Internet
  • With XML and DTDs, keyword searches on the
    Internet can now be aimed at the appropriate
    systems, databases, pages
  • A syntactic search using IE
  • cook New York kitchen restaurant
  • would become
  • A semantic search
  • ltoccupationgtcooklt/occupationgt
  • ltcitygtNew Yorklt/citygt

21
VXML
  • Voice XML - vxml
  • Sound embedded as content and processed as per
    style sheet
  • Other media types will be used as well
  • W3C references
  • vxml examples

22
General XML References
  • http//www.w3.org/XML/
  • http//www.xmlfiles.com/xml/
  • http//xml.sys-con.com/

23
What is an Ontology?
  • A specification of a conceptualization
  • Example
  • An Author is a person
  • An Author writes text, books, poems, stories
  • A book may have two Authors
  • A well understood semantic schema
  • A description of the concepts and relationships
    that exist for an agent or community of agents
  • A set of terms describing the application domain
  • A set of definitions of formal vocabulary for
    communication between agents

24
What is an Ontology used for?
  • To enable information and knowledge sharing and
    reuse between different applications
  • Useful for human understanding and interaction
  • An XML DTD is a primitive form of ontology but
    lacks the ability to capture complex
    relationships between terms
  • Good first link on Ontologies http//www.aaai.org
    /AITopics/html/ontol.html

25
Ontology use in Artificial Intelligence
  • Originally designed for use in AI
  • Uses in the AI field
  • Knowledge Engineering
  • Natural Language Processing
  • Intelligent Information Integration
  • Popularized during the movement to create XML and
    the use of XML by Intelligent Agents of the
    Semantic Web

26
A Great Introduction to
  • XML, Ontologies, and the Semantic Web

27
Applications of Ontologies
  • Knowledge Engineering
  • Semantic Web share/exchange of knowledge
  • Semi-structured Data web pages
  • Ontology-based Information Systems Geographic
    IS, Legal IS, Business IS
  • Ontologies Machine Learning / Knowledge
    Discovery
  • E-Business / E-Commerce

28
Application to Knowledge Management
  • Efficient knowledge management has been
    identified as key to maintaining the
    competitiveness of organizations.
  • Ontologies have been developed in the knowledge
    engineering discipline as a means to share and
    reuse knowledge
  • Has been used in large company-wide networks,
    call centers, B2C and B2B E-Commerce

29
Whats AheadTechnology, Software, Languages
  • Ontologies and XML
  • Ontology Exchange Language (XOL)
  • Technologies
  • KQML(Knowledge Query and Manipulation Language)

30
Ontologies and XML
  • XML is emerging as the standard language for data
    interchange on the web
  • Desirable to exchange ontologies using XML syntax
  • Has led to development of XML based languages,
    defining a language on top of XML

31
Ontologies and XML
  • XML Based Languages
  • SHOE
  • Ontology Exchange Language (XOL)
  • Ontology Markup Language (OML)
  • Resource Description Framework Schema Language
    (RDFS)
  • Riboweb
  • OIL (Ontology Interface Layer) - extention of
    RFDS

32
Ontology Exchange Language (XOL)
  • Language for the exchange of ontologies, created
    to facilitate the creation of shared ontologies
  • Example can be applied to databases to make
    information sharing easier

33
Technologies
  • Ontology Editors
  • - the creation of joint ontologies for a number
    of agents is challenging
  • - distributed development of ontologies needs
    tools for synchronizing
  • - Examples Protégé
  • Webonto
  • OILed

34
Technologies
  • MetaData Editors
  • - ontologies can also be used along with meta
    data
  • - ontology aware metadata tools simplify the
    creation of metadata for web resources
  • - Reggie MetaData Editor - an example of a
    simple java based editor

35
KQML (Knowledge Query and Manipulation Language)
  • Language and protocol for exchanging information
    and knowledge
  • Both a message format and message-handling
    protocol to support run-time knowledge sharing
    among agents
  • Uses
  • As a language for an application program to
    interact with an intelligent system
  • For two or more intelligent systems to share
    knowledge

36
KQML (Knowledge Query and Manipulation Language)
  • Provides a basic architecture for knowledge
    sharing through a special class of agent called
    communication facilitators which coordinate the
    interactions of other agents
  • Being used in concurrent engineering, intelligent
    design and intelligent planning and scheduling

37
OIL(Ontology Interface Layer)
  • Ontologies will play a major role in supporting
    information exchange
  • A prerequisite for this role is the development
    of a joint standard for specifying and exchanging
    ontologies
  • The Ontology Interface Layer protocol is a
    proposal for such a standard
  • Proposal for web-based representation and
    inference layer for ontologies
  • What OIL is trying to achieve - to ensure a Web
    where information can be understood by machines
    as well as by humans

38
Ontologies Step by Step
  • http//www.cs.umd.edu/users/hendler/sciam/walkthru
    .html

39
Ontologies and The Semantic Web
  • The next evolutionary step for the Web is the
    Semantic Web
  • Idea of WWW inventor Tim Berners-Lee
  • The semantic web is a mesh of information linked
    so it is easily processed by machines
  • Will allow meaningful exchange of information and
    reasoning on the World Wide Web
  • Resource Description Framework (RDF)
    http//www.xml.com/pub/a/2001/01/24/rdf.html

40
Ontologies and The Semantic Web
  • Ontologies that will allow machines to easily
    understand each other
  • Software agents will be able to understand and
    work with the words and info humans use in
    emails, documents and databases
  • Ontologies and the semantic web will make
    searching for things on the web much easier
  • Will automate many time consuming low-level
    tasks, for example

41
Summary
  • An ontology is basically a formal specification
    to enable communication between agents
  • Used for knowledge sharing among computers and
    people
  • Ontologies are a core component behind the
    Semantic Web which is the future of the Internet

42
References
  • http//www.aaai.org/AITopics/html/ontol.html
  • http//www-ksl.stanford.edu/kst/what-is-an-ontolog
    y.html
  • http//www.cs.umd.edu/users/hendler/sciam/walkthru
    .html
  • http//ecommerce.ncsu.edu/technology/topic_XML.htm
    l
  • http//ksl-web.stanford.edu/kst/ontology-sources.h
    tml
  • http//www.cs.umbc.edu/kqml/

43
THE ENDdanny.silver_at_acadiau.ca
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