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What is XML (and RDF)?. John McCarthy & Frank Olken [email protected] [email protected] Lawrence Berkeley National Laboratory Roy Tennant [email protected] The Library, University of California, Berkeley. http://www.lbl.gov/~olken/epa.html Metadata Registries Workshop II

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What is xml and rdf

What is XML (and RDF)?

John McCarthy & Frank Olken

[email protected]@lbl.gov

Lawrence Berkeley National Laboratory

Roy Tennant

[email protected]

The Library, University of California, Berkeley


Metadata Registries Workshop II

Washington, DC 15 April 1998

Xml extensible markup language
XML: Extensible Markup Language

  • World Wide Web Consortium (W3C) Recommendation, Version 1.0 February 1998

  • Simplified SGML (Standard Generalized Markup Language, ISO 1986)

    • adopts UNICODE international character set

  • Next generation HTML:

    • semantic structure of document or data

    • extensible, industry-specific tag sets

    • display determined by stylesheets (CSS, XSL)

A simple xml example
A Simple XML Example

<?xml version=“1.0”?>



<name>Richard Light</name>

<email>[email protected]</email>


<title>Presenting XML</title>



Character Data

Goals philosophy of xml
Goals & Philosophy of XML

  • Overcomes shortcomings of HTML:

    • allows processing of Web documents by sophisticated document processing software

  • Overcomes shortcomings of SGML:

    • allows media-independent electronic publishing

  • Interoperates with SGML and HTML

  • Provides vendor-neutral data exchange

Xml history
XML History

  • Roots in SGML

    • very extensible but very complicated

    • a simplified SGML could greatly expand the power and flexibility of the Web

  • XML proposal to W3C in July 1996

    • John Bosak, Sun Microsystems, now XML Chair

  • First XML Meeting, August 1996, Seattle

Xml family of standards
XML Family of Standards

  • XML (W3C Proposal, Version 1.0 February 1998)

    • simplified SGML (ISO 8879:1986)

  • Extensible Stylesheet Language (XSL)

    • based on DSSSL (stylesheet specification ISO/IEC 10179, used for SGML)

  • XML Linking Language (XLink)

    • based on HyTime (ISO/IEC 10744:1992)

    • provides rich linking mechanisms (e.g., multidirectional links)

What is w3c
What is W3C?

  • World Wide Web Consortium (www.w3.org)

    • Tim Berners-Lee, Director

  • Staff at MIT, US; INRIA, France; Keio Univ., Japan

  • Over 220 member organizations (April 1998)

    • for profit > $50,000,000 pay $50,000/year

    • other for profit, gov’t, and non profit pay $5,000/year

  • Fast track Web standards development

  • Short-term, specific focus Working Groups

Current w3c development areas
Current W3C Development Areas

  • Architecture

    • HTTP-NG, etc.

  • User Interface

    • HTML, CSS, XSL, etc.

  • Privacy and Site Rating

    • P3P, PICS, etc.

  • Data Exchange

    • XML, RDF, etc.

Xml bandwagon
XML Bandwagon

  • Major support from vendors:

    • Microsoft, Sun, Netscape, ...

    • High-end technical publishers (SGML)

  • Conferences:

    • SGML/XML, November 1997, Wash. DC

    • XML Conference, March 1998, Seattle

    • SGML/XML, May 1998, Paris

    • XML World, September 1998, Ottawa

  • Books, Software, Web sites, Articles

Xml software tools
XML Software Tools

  • XML-enabled Web browsers

    • e.g., Microsoft Internet Explorer, Netscape

  • XML parsers

    • e.g., http://www.microsoft.com/xml/

  • XML stylesheet editing software

    • e.g., http://www.arbortext.com/xmlstyler/

  • CDF (Channel Definition Framework)

    • e.g., http://www.microsoft.com/standards/cdf.htm

  • Software for structured text

    • Survey: http://www.cs.uku.fi/~kuikka/systems.html

    • Pointers: http://www.sil.org/sgml/publicSW.html

    • SoftQuad (www.sq.com), Arbortext (www.arbortext.com)

Discipline specific proposals
Discipline-Specific Proposals

  • Chemical Markup Language (ChemML)

  • Math Markup Language (MathML)

  • Electronic Document Interchange (XML-EDI)

  • Bioinformatic Sequence Markup Language (BSML)

  • Synchronized Multimedia Integration Language (SMIL)

  • Web Interface Definition Language (WIDL)

  • Precision Graphics Markup Language (PGML)

  • Information and Content Exchange (ICE)

  • Tutorial Markup Language (TML)

  • Open Software Description Format (OSD)

Xml and edi

  • XML-EDI Group within Graphic Communications Association

  • XML-EDI being examined in X12

  • CommerceNet Industry Initiative

    • creating tag sets for EDI

  • Telecommunications Interchange Markup (TCIF/IPI)

  • More information:

    • http://www.xmledi.org/


General proposals
General Proposals

  • W3C Document Object Model (DOM)

    • enables script access to document components

  • Channel Definition Format (CDF)

    • specifications for push content

  • XML-Data (Note from Microsoft)

    • XML encoding for DTDs and data types

  • Resource Description Framework (RDF)

    • metamodel for Web metadata

Resource description framework
Resource Description Framework

  • Interoperability for applications that use metadata

  • Enables industry-specific groups to independently define, maintain, and reuse vocabularies (schemas)

  • Architecture includes:

    • Graph data model (like NIAM, AI frames)

    • Transfer syntax (XML) for interchange

    • Human-readable and machine-parseable syntax

  • RDF Working Groups (http://www.w3.org/RDF/)

    • model and syntax

    • schema

Rdf architecture
RDF Architecture

XML replaces SGML and allows the expression of structure;

RDF allows the expression of semantics. - Tim Berners-Lee

Xml metadata registries
XML, Metadata & Registries

  • Encode metadata in XML (and RDF)

  • Use Registries to manage tag sets

  • For self-describing data and metadata exchange (transmission format)

  • Links to reference metadata registries

  • Use XML/RDF for registry schemas (metamodels)

W3c namespaces proposals
W3C Namespaces Proposals

  • Naming Contexts (e.g., ISO 11179)

  • Divide and conquer name collisions

  • Library of Congress <title> means book title:

    <?xml:namespace ns=“http://www.loc.gov/” prefix=“LC”>

    <LC:title>From Here to Eternity</LC:title>

  • Department of Commerce <title> means job title:

    <?xml:namespace ns=“http://www.doc.gov/” prefix=“C”>

    <C:title>Chief Bottle Washer</C:title>

  • W3X document on XML Namespaces

    • http://www.w3.org/TR/WD-xml-names

Mixing matching namespaces
Mixing & Matching Namespaces

<?xml:namespace ns=“http://books.org/” prefix=“B”?>

<?xml:namespace ns=“http://ecommerc.org/” prefix=“E”?>







<E:Item Price=“5.95”>


<B:Title>The Call of the Wild</B:Title>

<B:Author>London, Jack</B:Author>



Where xml is going
Where XML is Going

  • Increasing industry interest and acceptance

  • Parsers in multiple computer languages:

    • Java, C++, Perl, Python, etc.

  • Additional industry-specific tag sets

  • Full Web browser support

  • Growing set of authoring/processing tools

Xml resources
XML Resources

  • Standards proposals: http://www.w3.org/XML/

  • Web Sites:

    • Robin Cover: http://www.sil.org/sgml/xml.html

    • Seybold/O’Reilly: http://xml.com/

    • Web Review: http://webreview.com/xml/

  • Electronic Discussions:

  • Documents:

    • FAQ: http://www.ucc.ie/xml/

    • BYTE article: http://www.byte.com/art/9803/sec5/sec5.htm