Introduction to XML

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This introduction is part of the DH101 course. Check dh101.ch

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Introduction to XML

  1. 1. [STANDARD]XML #DH101
  2. 2. What is XML and what is it goodfor ? #DH101
  3. 3. XML stands for eXtensibileMarkup Language #DH101
  4. 4. To write in XMLyou write text with tags :<atag> my text </atag> #DH101
  5. 5. This can be done in any texteditor. #DH101
  6. 6. XML is a W3C recommandation. #DH101
  7. 7. 4characteristics #DH101
  8. 8. 1. XML is used to describe data,not to display them. XML doesnothing. It describes. #DH101
  9. 9. 2. XML tags are not prede!ned.You can de!ne your own tags.This gives you a lot of freedomto describe the structure youwant to describe. #DH101
  10. 10. 3. When you are satis!ed withyour structure, you can !x ourXML language by writing a DTD(Document Type Description).Thus, XML permits both "uidityand then rigor. #DH101
  11. 11. 4. XML is designed to be self-descriptive and “easily”readable. It is used to write“pivotal” descriptions inproduction chains. #DH101
  12. 12. Genealogy of XML #DH101
  13. 13. In the 50s, the !rst computerscould not communicate with oneanother, if they were fromdi#erent brands. #DH101
  14. 14. In the 60s, IBM creates GML(Generalized Markup Language)to enable data exchanges andmake the data structure explicit. #DH101
  15. 15. This is a great success. Itbecomes a standard : SGML(Standard Generalized MarkupLanguage).The US fed gov. adopts it. #DH101
  16. 16. In the 90s, Tim Berners-Lee atCERN creates the HTMLlanguage using a subset ofSGML. #DH101
  17. 17. HTML get specialized indisplaying data but does notimpose a standard way fordescribing data. #DH101
  18. 18. A group of researchers imaginesanother language to do this.The !rst version of XML isready in 1998. #DH101
  19. 19. XML vs HTML #DH101
  20. 20. XML is a markup language likeHTML. #DH101
  21. 21. XML is not a replacement ofHTML. The two languages havedi#erent goals. #DH101
  22. 22. XML is for the transport and thedescription of structured data.HTML is for the display andlayout of data. #DH101
  23. 23. XML does nothing.It just describes. #DH101
  24. 24. XML is like a database in plaintext. #DH101
  25. 25. Structure ofan XML !le #DH101
  26. 26. XML Element <TAG>Text</TAG>Opening tag Content Closing tag
  27. 27. <BOOK><TITLE>Da Vinci Code</TITLE><AUTHOR>Dan Brown</AUTHOR><YEAR>2003</YEAR></BOOK>
  28. 28. With XML, you can create yourown tags. #DH101
  29. 29. <BOOK><TITLE>Da Vinci Code</TITLE><AUTHOR>Dan Brown</AUTHOR><YEAR>2003</YEAR><STARS>4</STARS></BOOK>
  30. 30. An XML !le starts with theversion of XML used to describethe data and the text encodingformat. #DH101
  31. 31. <?xml version="1.0"encoding="ISO-8859-1"?><BOOK><TITLE>Da Vinci Code</TITLE><AUTHOR>Dan Brown</AUTHOR><YEAR>2003</YEAR></BOOK>ISO-8859-1 = Latin-1/West Europeancharacter set
  32. 32. An XML document is organizedlike a tree. #DH101
  33. 33. <BOOK> <FRONT> <TITLE>... </TITLE> <AUTHOR>...</AUTHOR> </FRONT> <BODY>  <PART>    <CHAPTER>...</CHAPTER>  </PART> </BODY></BOOK>
  34. 34. DTD #DH101
  35. 35. A well-formed XML documentfollows the general rules ofXML syntax. #DH101
  36. 36. A valid XML document followsthe speci!c rules written in aDTD (Document TypeDescription) #DH101
  37. 37. <!DOCTYPE BOOK[<!ELEMENT BOOK(TITLE,AUTHOR,YEAR)><!ELEMENT TITLE (#PCDATA)><!ELEMENT AUTHOR (#PCDATA)><!ELEMENT YEAR (#PCDATA)>]>
  38. 38. To use a DTD is not mandatory. #DH101
  39. 39. A DTD permits to agree oncommon XML dialect. #DH101
  40. 40. Some software permit to checkwhether an XML !le is validcompared to a given DTD. #DH101
  41. 41. Displaying XML #DH101
  42. 42. The way an XML !le is displayedcan be speci!ed in a CSSstylesheet. #DH101
  43. 43. BOOK{display: block;margin-bottom:30pt;margin-left: 0;}TITLE{display: block;color: #FF0000;font-size: 40pt;margin-left: 20pt;}AUTHOR{display: block;color: #0000FF;font-size: 30pt;margin-left: 20pt;}YEAR{display: block;color: #000000;font-size: 30pt;margin-left: 20pt;}
  44. 44. <?xml-stylesheet type="text/css" href="book.css"?>
  45. 45. A document can also betransformed using an XSLTscript. This is now therecommended method #DH101
  46. 46. XML >> #DH101
  47. 47. XML permits to separate formfrom content by identifyingstructures reccurent to severaldocuments. #DH101
  48. 48. Transformation Target TargetSource Engine XML InDesign Indesign XSLT XSL-FO/PDF Paper / PDF ebook XHTML website XML Tablet ePub Webapp Reader Smartphone TXT MP3 player XML TEI / Doc Book Computer systems
  49. 49. >> XML #DH101
  50. 50. Word Database XMLScanned document Sensors ...

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