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XML Basics

XML Basics. A technical introduction Felix Eickhoff felix.eickhoff@gmx.net. Overview. Why XML XML Fundamentals Document Type Definitions XML Schemas Namespaces in XML XSL Transformations X P ath X L inks X P ointers. Why XML. W3C endorsed standard Generic syntax to mark up data

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XML Basics

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  1. XML Basics A technical introduction Felix Eickhoff felix.eickhoff@gmx.net

  2. Overview • Why XML • XML Fundamentals • Document Type Definitions • XML Schemas • Namespaces in XML • XSL Transformations • XPath • XLinks • XPointers

  3. Why XML • W3C endorsed standard • Generic syntax to mark up data • More flexible than HTML • Need for sharing data

  4. XML Fundamentals • XML Version, Doctype • Elements • Start and End Tag • Attributes • Case sensitive • Contain other elements or data • Comments • Well formedness

  5. XML Fundamentals - Example <?xml version=„1.0“?><?DOCTYPE address-book SYSTEM „address-book.dtd“?> <address-book> <entry> <PersonName honorific=„Ms.“> <SingleName>Doe</SingleName> <PersonName/> <address> <street>34 Fountain Square Plaza</street> <postal-code>45202</postal-code> </address> <tel prefered=„true“>515-73737</tel> <tel>515-28378</tel> <email href=„mailto:jdoe@mail.com“/> </entry> <entry> <PersonName honrorifc=„Mr.“><FirstName>Jack</FirstName> <MiddleName>Phillip</MiddleName> <LastName>Smith</LastName></PersonName> <tel>737-378477</tel> <email href=„mailto:jsmith@mail.com“/> </entry> </address-book>

  6. XML Trees – Example

  7. Document Type Definitions - DTD • Defines language grammar for a particular XML application • What for: • Specific XML applications • Validation of XML-files

  8. DTD - Example <!ELEMENT address-book (entry+)> <!ELEMENT entry (name, address*, tel*, fax*, email*)> <!ELEMENT PersonName (SingleName|(FirstName, MiddleName*, LastName))> <!ELEMENT FirstName (#PCDATA)> <!ELEMENT MiddleName (#PCDATA)> <!ELEMENT LastName (#PCDATA)> <!ELEMENT SingleName (#PCDATA)> <!ELEMENT address (street, postal-code> <!ELEMENT street (#PCDATA)> <!ELEMENT postal-code (#PCDATA)> <!ELEMENT tel (#PCDATA)> <!ATTLIST tel preferred (true | false) „false“> <!ELEMENT fax (#PCDATA)> <!ATTLIST fax preferred (true | false) „false“> <!ELEMENT email EMPTY> <!ELEMENT email href CDATA #REQUIRED preferred (true|false) „false“>

  9. Document Type Defintions • Element Declaration • #PCDATA, EMPTY, ANY • Sequences • Using regular Expressions (* , + ,| ) • Attribute Declaration • CDATA, NMTOKEN, ENUMERATION, ENTITY, ID, IDREF, NOTATION, #REQUIRED, #IMPLIED, #FIXED • Entities • Internal and External

  10. XML Schemas • Alternative to DTD • XML Syntax • Data Typing • Content Models • Extensible • Dynamic Schemas • Self Documenting

  11. XML - Example <?xml version=„1.0“?><?DOCTYPE address-book SYSTEM „address-book.xsd“ <address-book> <entry> <PersonName honorific=„Ms.“> <SingleName>Doe</SingleName> <PersonName/> <address> <street>34 Fountain Square Plaza</street> <postal-code>45202</postal-code> </address> <tel prefered=„true“>515-73737</tel> <tel>515-28378</tel> <email href=„mailto:jdoe@mail.com“/> </entry> <entry> <PersonName honorific=„Mr.“><FirstName>Jack</FirstName> <MiddleName>Phillip</MiddleName> <LastName>Smith</LastName></PersonName> <tel>737-378477</tel> <email href=„mailto:jsmith@mail.com“/> </entry> </address-book>

  12. XML Schema - Example <?xml version=„1.0“ ?> <schema xmlns=„http://www.w3.org/2000/10/XMLSchema“> <simpleType name=„Person Title“> <restriction base=„string“> <enumeration value=„Mr.“/> <enumeration value=„Ms.“/> </restriction> </simpleType> <complexType name=„Text“ content=„textonly“> <restriction base=„string“ /> </complexType>

  13. XML Schema – Example (2) <element name=„PersonName“> <complexType content=„element“> <choice> <element name=„Single Name“ type=„Text“ minOccurs=„1“ maxOccurs=„1“/> <sequence> <element name=„FirstName“ type=„Text“ minOccurs=„1“ maxOccurs=„1“/> <element name=„MiddleName“type=„Text“ minOccurs=„1“ maxOccurs=„unbounded“/> <element name=„LastName“ type=„Text“ minOccurs=„1“ maxOccurs=„1“/> </sequence> </choice> <attribute name=„honorific“ ref=„PersonTitle“/> </complexType> </element> ... </schema>

  14. Namespaces in XML • Distinguish between elements and attributes from different XML applications • Group related elements and attributes together • Based on unique Domain-Names

  15. Namespace - Example <?xml version=„1.0“ ?> <catalog> <painting> <title>Memory of the Garden of Etten</title> <artist>Vincent Van Gogh</artist> <date>November, 1888</date> <description> Two women ... </description> </painting> <!– Many more paintings... --> </catalog>

  16. Namespace – Example(2) <?xml version=„1.0“ ?> <RDF> <Description about=„http://name.com/impressionists.html“> <title>Impressionists Paintings</title> <creator>Joe Doe</creator> <description> A list of famous impressionist paintings organized by painter and date </description> <date>2001-10-05</date> </Description> </RDF>

  17. Namespace – Example(3) <?xml version=„1.0“ ?> <catalog> <RDF> <Description about=„http://name.com/impressionists.html“> <title>Impressionists Paintings</title> <creator>Joe Doe</creator> <description> A list of famous impressionist paintings organized by painter and date </description> <date>2001-10-05</date> </Description> </RDF> <painting> <title>Memory of the Garden of Etten</title> <artist>Vincent Van Gogh</artist> <date>November, 1888</date> <description> Two women ... </description> </painting> </catalog>

  18. Namespace – Example(4) <?xml version=„1.0“ ?> <catalog> <rdf:RDF xmlns:rdf=„http://www.w3.org./TR/REC-rdf-synstax#“> <rdf:Description xlmns:dc=„http://purl.org/dc“ about=„http://name.com/impressionists.html“> <dc:title>Impressionists Paintings</dc:title> <dc:creator>Joe Doe</dc:creator> <dc:description> A list of famous impressionist paintings organized by painter and date </dc:description> <dc:date>2001-10-05</dc:date> </rdf:Description> </rdf:RDF> <painting> <title>Memory of the Garden of Etten</title> <artist>Vincent Van Gogh</artist> <date>November, 1888</date> <description> Two women ... </description> </painting> </catalog>

  19. XSL Transformations • High-level language for defining XML Transformations • Format information for Display • Useful for managing data exchange • Report Writing • Work done by Stylesheet processors

  20. Stylesheet – Example Input <?xml version=„1.0“ ?> <people> <person born=„1912“ died=„1954“> <name> <first_name>Alan</first_name> <last_name>Turing</last_name> </name> <profession>computer scientist</profession> <profession>mathematican</profession> <profession>cryptographer</profession> </person> <person born=„1918“ died=„1988“> <name> <first_name>Richard</first_name> <middle_initial>M</middle_initial> <last_name>Feyman</last_name> </name> <profession>physicist</profession> <hobby>Playing the bongoes</hobby> </person> </people>

  21. Stylesheet – Example <?xml version=„1.0“?> <xsl:stylesheet version=„1.0“ xmlns:xsl=„http://www.w3.org/1999/XSL/Transform“> <xsl:template match=„people“> <html> <head><title>Famous Scientists</title></head> <body> <dl> <xls:apply-templates/> </dl> </body> </html> </xsl:template>

  22. Stylesheet – Example (2) <xsl:template match=„person“> <dt><xsl:apply-templates select=„name“/></dt> <dd><ul> <li>Born: <xsl:apply-templates select=„@born“/></li> <li>Died: <xsl:apply-templates select=„@died“/></li> </ul></dd> </xsl:template> <xsl:template match=„name“> <xsl:value-of select=„last_name“/> <xsl:value-of select=„first_name“/> </xsl:template> </xsl:stylesheet>

  23. Stylesheet – Example Output <html> <head> <title>Famous Scientists</title> </head> <body> <dl> <dt> Alan Turing </dt> <dd> <ul> <li>Born: 1912</li> <li>Died: 1954</li> </ul> </dd> ... </dl> </body </html>

  24. XSL – More features • Uses XPath functions • If-statements, For each loops • Parameters for templates • => Query language

  25. XPath • Identifies particular parts of XML documents • Navigate on the tree structures of XML documents like in a UNIX file system • Many built-in functions • e.g.:round, starts-with, substring, ... • Used by XSLT, XPointer

  26. XPath – Example <xsl:template match=„people“> <xsl:apply-template select=„person“/> </xsl:template> <xsl:template match=„person“> <xsl:value-of select=„name“/> </xsl:template>

  27. XPath – Example (2) <xsl:template match=„person“> <xsl:apply-templates select=„@*“/> </xsl:template> <xsl:template match=„last_name|profession“> <xsl:value-of select=„.“/> </xsl:template>

  28. XPath – Example (3) /people/person/name/first_name //last_name/../first_name <xsl:template match=„//profession[.=‚Computer Scientist‘]“> <xsl:apply-template select=„//person[@born&lt;=1980“/>

  29. XLink • Simple Links • Like Links in HTML • Extended Links • More than one target possible • Directed labeled graph • Representation undecided yet • Arcs • Links between other recources

  30. XLink – Simple Link Example <?xml version=„1.0“?> <novel xmlns:xlink=„http://www.w3.org/1999/xlink“ xlink:type=„simple“ xlink:href=„ftp://someserver.com/books/novels/wizoz.txt“ xlink:actuate=„onRequest“ xlink:show=„replace“ xlink:title=„A Link to the wonderful wizard ...“ xlink:role=„http://moreinfo.com“> <title>The wonderful wizard of oz</title> <author>Frank Baum</author> </novel>

  31. XLink – Extended Link Example <?xml version=„1.0“?> <novel xmlns:xlink=„http://www.w3.org/1999/xlink“ xlink:type=„extended“> <title>The wonderful wizard of oz</title> <author>Frank Baum</author> <edition xlink:type=„locator“ xlink:href=„urn:isbn:123456“ xlink:title=„William Morrow“ xlink:role=„http://www.williammorrow.com/“ xlink:label=„ISBN123456“/> <edition xlink:type=„locator“ xlink:href=„urn:isbn:234567“ xlink:title=„Oxford University Press“ xlink:role=„http://www.oup-usa.org/“ xlink:label=„ISBN234567“/> </novel>

  32. XLink – Arcs Example <?xml version=„1.0“?> <series xlink:type=„extended“ xmlns:xlink=„http://www.w3.org/1999/xlink“> <author>Frank Baum</author> <!–- locator elements --> <novel xlink:type=„locator“ xlink:label=„oz1“ xlink:href=„ftp://someserver.com/wizoz.txt“> <title>The wonderful wizard of oz</title> </novel> <novel xlink:type=„locator“ xlink:label=„oz2“ xlink:href=„ftp://someserver.com/ozland.txt“> <title>The marvelous land of oz</title> </novel> <novel xlink:type=„locator“ xlink:label=„oz3“ xlink:href=„ftp://someserver.com/ooz.txt“> <title>Ozma of oz</title> </novel>

  33. XLink – Arcs Example (2) <!–- arcs --> <next xlink:type=„arc“ xlink:from=„oz1“ xlink:to=„oz2“ /> <next xlink:type=„arc“ xlink:from=„oz2“ xlink:to=„oz3“ /> <next xlink:type=„arc“ xlink:from=„oz2“ xlink:to=„oz1“ /> <next xlink:type=„arc“ xlink:from=„oz3“ xlink:to=„oz2“ /> </series> The wonderful world of oz Ozma of oz The marvelous land of oz

  34. XPointer • Locates points in XML documents • Based on XPath In XLinks: http://www.someserver.com/xml/people.xml#xpointer (//name[position()=1]) xpointer(/) to the root xpointer(//first_name) Xpointer(//profession[.=„physicist“])

  35. References • XML in a NutshellElliotte Rusty Harold & W. Scott MeansO‘Reilly • Professional XML DatabasesKevin WilliamsWROX • http://xml.coverpages.org

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