([e-mail])

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Why is XML not only one more data exchange
format?
(christine.vanoirbeek_at_epfl.ch) EPFL IC School
Center for Global Computing
http//globalcomputing.epfl.ch
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Objective of the talk

• Argue in favour of the XML  paradigm  as a
  promising approach to deal with distributed
  information systems over the Internet
• XML is not new (very close to SGML)
• What are the differences?
• Why so much attention is paid to XML?
• What is the potential and current limitations of
  XML?

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The XML paradign
Internet
Unicode
Intranet
HTML
XML
SGML
TIFF
TCP/IP
GIF
HTTP
DTD
XML-Schema
WAIS
Jpeg
Mpeg-4
HyTime
Java
DSSSL
XLink
Servlet
Applet
WWW
XPath
XSL
XPointer
CSS
DOM
SAX
Web Services
Postscript
SVG
SMIL
JDBC
UML
SQL
DBMS
PDF
Corba
MathML
CML
RDF
OWL
XML Query
ThML
ASP
PHP
DC (DCMI)
Mpeg-7
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A little bit of history!

• Dealing with structured documents
• Document Type Definition (DTD)

lt!ELEMENT recipe (title, comment, item,
picture?)gt lt!ATTLIST recipe type CDATA
REQUIRED nbPers CDATA
REQUIRED difficulty (easy
medium difficult) IMPLIED gt
Advantage validation!
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A little bit of history!

• Dealing with structured documents
• Distinction between content layout (use of
  stylesheets)

Document
Content
Advantage One content ... multiple
presentations!
...
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XSL eXtented Stylesheet Language

• A powerful mechanism to generate data from XML
  content

XSLT processor
XML source
Result(XML, HTML, )
XSLT stylesheet
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Use of XSL an example
ltAUCTIONBLOCKgt ltITEMgt ltTITLEgtVase and
Stoneslt/TITLEgt ltARTISTgtLinda Mannlt/ARTISTgt
ltDIMENSIONSgt20x30 incheslt/DIMENSIONSgt
ltPREVIEW-SMALL src"burl-s.jpg" width"300"
height"194" /gt ltBIDSgt ltBIDgt
ltPRICEgt6000lt/PRICEgt ltTIMEgt30222
PMlt/TIMEgt ltBIDDERgtChrislt/BIDDERgt
ltTIMESTAMPgt1307lt/TIMESTAMPgt lt/BIDgt
ltBIDgt lt/BIDgt lt/BIDSgt lt/ITEMgt
lt/AUCTIONBLOCKgt
(Source Microsoft)
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Use of XSL an example
Differently sorted!
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Use of XSL an example
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XSL some remarks

• More than styling
• Transformation
• Sort
• Process (to a certain extent!)
• Consequence
• XML is mainly used for storing data (not
  documents)
• Extracted from databases
• Transformed via XSL-T (mostly for producing HTML
  files)

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Another piece of the puzzle (XML Schema)

• Dealing with structured documents
• XML Schema

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Another piece of the puzzle (XML Schema)

• Dealing with structured documents
• XML Schema

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XML Schema some remarks

• XML Schema is used for modelling data
• Catalog, Directories,
• Main differences in comparison with DTDs
• Typed data, object oriented design, notion of
  key, etc.
• The data model is described using the XML syntax!
• Consequence
• Towards a uniformization of technics for
• Editing
• Transforming
• Processing
• Publishing

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Use of XML for describing metadata

• Objective to facilitate work performed by search
  engines
• Towards the semantic web!
• RDF (Ressource Description Framework)
• OWL (Web Ontology Language)
• Dublin Core
• MPEG-7 (metadata on video)

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Whats happening with XML?

• XML is used
• For representing data
• As exchange format
• To agree on common vocabularies structures

Health Level Seven (HL7)
http//www.hl7connect.com/
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The use of XML is not limited to textual info.

• SVG (Scalable Vector Graphics)
• MathML

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The use of XML is not limited to textual info.

• SMIL Synchronized Multimedia Integration Language

SMIL specification
ltseqgt lt/seqgt ltpargt lt/pargt
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Web services building XML based applications
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Web services building XML based applications

• A  full Web Service  is a software component
• Available on the net (URI)
• To be invoked (SOAP, HTTP, TCP/IP, SMTP, MIME)
• Described (WSDL)
• Published and searchable (UDDI)
• That may be orchestrated with other web services

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Concluding remarks

• ()
• Convergence of technologies to
• Deal with data AND document (incl. multiple
  modalities)
• Process information
• Link data and processing operations
• Information is reusable!
• (-)
• Authoring XML documents remains a tedious task
• XML dabases (what is the evolution?)