Introduction to XML

1
Introduction toXML
? Dr. Eshaa M. Alkhalifa
2
Predefined tags vs Your tag names

• XHTML example
• ltHTMLgt ltH1 ID"MN"gtStatelt/H1gt ltH2
  ID"12"gtCitylt/H2gt ltDLgt ltDTgtNamelt/DTgt
  ltDDgtJohnsonlt/DDgt ltDTgtPopulationlt/DTgt
  ltDDgt5000lt/DDgt lt/DLgt ltH2 ID"15"gtCitylt/H2gt ltDLgt
  ltDTgtNamelt/DTgt ltDDgtPinevillelt/DDgt
  ltDTgtPopulationlt/DTgt ltDDgt60000lt/DDgt lt/DLgt ltH2
  ID"20"gtCitylt/H2gt ltDLgt ltDTgtNamelt/DTgt ltDDgtLake
  Belllt/DDgt ltDTgtPopulationlt/DTgt ltDDgt20lt/DDgt lt/DLgt
  lt/HTMLgt

• XML example
• lt?XML VERSION"1.0" STANDALONE"yes" ?gt ltSTATE
  STATEID"MN"gt ltCITY CITYID"12"gt
  ltNAMEgtJohnsonlt/namegt ltPOPULATIONgt5000lt/POPULATIONgt
  lt/CITYgt ltCITY CITYID"15"gt ltNAMEgtPinevillelt/NAMEgt
  ltPOPULATIONgt60000lt/POPULATIONgt lt/CITYgt ltCITY
  CITYID"20"gt ltNAMEgtLake Belllt/NAMEgt
  ltPOPULATIONgt20lt/POPULATIONgt lt/CITYgt lt/STATEgt

3
eXtensible Markup Language?

• Last edition is defined here http//www.w3.org/TR/
  2006/REC-xml11-20060816/

• XML
• Describes what the data IS
• Displaying it directly will only show the
  structure of the data

• HTML
• Describes how a page looks
• Can be displayed directly onto a browser

4
Future of the Internet?

• Yes and No
• Yes because it makes it easier to maintain large
  sites and pages.
• No because it will not replace HTML or will it?

5
How is XML really different?
XML Alone XML Using XSL
6
What Does this mean?

• You write two files
• XML file to hold your data alone, and you set the
  structure of the file.
• XSL file to hold the structure of how your data
  is displayed.
• This means you can alter, add, delete parts of
  the displayed page without having to alter the
  way the page looks.
• E.g. pages with news

7
XML File

• An XML file may look like this
• lt?xml version"1.0" encoding"ISO8859-1" ?gt
• lt?xml-stylesheet type"text/xsl"
  href"testxsl.xsl"?gt
• ltnotegt
• ltTOgtTovelt/TOgt
• ltfromgtJanilt/fromgt
• ltheadinggtReminderlt/headinggt
• ltbodygtDon't forget me this weekend!lt/bodygt
• lt/notegt

8
XSL File

• lt?xml version'1.0'?gt
• ltxslstylesheet xmlnsxsl"http//www.w3.org/TR/WD
  -xsl"gt
• ltxsltemplate match"/"gt
• lthtmlgt ltbody bgcolor"yellow"gt
• lth1gtReferences Data Internal Notelt/h1gt
• ltxslfor-each select"note"gt
• ltbgtTo lt/bgtltxslvalue-of select"TO" /gt ltbr
  /gt
• ltbgtFrom lt/bgtltxslvalue-of select"from" /gt
  lthr /gt
• ltbgtltxslvalue-of select"heading" /gtlt/bgt
  lthr /gt
• ltxslvalue-of select"body" /gt
• lt/xslfor-eachgt
• lt/bodygt lt/htmlgt
• lt/xsltemplategtlt/xslstylesheetgt

9
XML Basics

• XML tags are not predefined, you make your own
  tag names.
• XML can use a DTD (Document Type Definition) to
  formally describe the data
• XML can store data in HTML pages as data
  islands
• XML can be used to exchange data
• All XML documents must have a root tag (like
  lthtmlgt for html documents)

10
Viewing XML

• Well formed XML documents a document that
  conforms to XML syntax rules (xhtml)
• Valid XML documents well formed and conforms
  to the rules of a DTD (Document Type Definition).

• Error
• In
• XML

11
Viewing XML in the Internet Explorer

• To see an open XML file follow this URL
• http//www.xmlfiles.com/examples/simple.xml
• To see an XML that uses XSL
• http//www.xmlfiles.com/examples/simplexsl.xml

12
XSL eXtensible Stylesheet Language

• Similar to CSS but this is from XML
• It can do two basic functions
• Transform XML into a format that can be
  displayed by the browser.
• Format the document by selective display of
  items through filtering and sorting of output
  plus more.

13

• lt?xml version"1.0" encoding"ISO8859-1" ?gt
  lt?xml-stylesheet type"text/xsl"
  href"cd_catalog.xsl"?gt ltCATALOGgt ltCDgt
  ltTITLEgtEmpire Burlesquelt/TITLEgt ltARTISTgtBob
  Dylanlt/ARTISTgt ltCOUNTRYgtUSAlt/COUNTRYgt
  ltCOMPANYgtColumbialt/COMPANYgt ltPRICEgt10.90lt/PRICEgt
  ltYEARgt1985lt/YEARgt lt/CDgt

• lt?xml version'1.0'?gt ltxslstylesheet
  xmlnsxsl"http//www.w3.org/TR/WD-xsl"gt
• ltxsltemplate match"/"gt lthtmlgt ltbodygt lttable
  border"2" bgcolor"yellow"gt lttrgt ltthgtTitlelt/thgt
  ltthgtArtistlt/thgt lt/trgt ltxslfor-each
  select"CATALOG/CD"gt lttrgtlttdgt
• ltxslvalue-of select"TITLE"/gt lt/tdgt
  lttdgtltxslvalue-of select"ARTIST"/gtlt/tdgt lt/trgt
  lt/xslfor-eachgt lt/tablegt lt/bodygt lt/htmlgt
  lt/xsltemplategt lt/xslstylesheetgt

14
You can see how they relate

• The XSL files name is mentioned in the XML file.
• The XML repeated element is mentioned in the XSL
  and so are the child elements
• ltxslvalue-of select"TITLE"/gt
• Will get a copy of that value for display

15

• IF
• ltxslfor-each select"CATALOG/CD"gt ltxslif
  match".ARTIST'Bob Dylan'"gt lt/xslifgt
  lt/xslfor-eachgt
• CHOOSE
• ltxslfor-each select"CATALOG/CD"gt lttrgt
  lttdgtltxslvalue-of select"TITLE"/gtlt/tdgt
  ltxslchoosegt ltxslwhen match".ARTIST'Bob
  Dylan'"gt . lt/xslwhengt
• ltxslotherwisegt lt/xslotherwisegt lt/xslchoosegt
  
• lt/trgt lt/xslfor-eachgt

16

• Sorting
• ltxslfor-each select"CATALOG/CD" order-by"
  ARTIST"gt
• Filter
• ltxslfor-each select"CATALOG/CD ARTIST'Bob
  Dylan'"gt

17

• Now you are ready to start your Practice sessions