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XML Technologies

XML Technologies. X-Languages. Contents. X Link X Pointer X Path X Query (Brief) X Form (Brief) XSLT FO. X Languages. X Query XPointer XLink. X Path XSLT. X Link. Standard way of defining hyperlinks in XML Short for XML Linking

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XML Technologies

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  1. XML Technologies X-Languages

  2. Contents • X Link • X Pointer • X Path • X Query (Brief) • X Form (Brief) • XSLT • FO

  3. X Languages X Query XPointer XLink X Path XSLT

  4. X Link • Standard way of defining hyperlinks in XML • Short for XML Linking • Similar to HTML Links but more powerful • Any element can have an XLink

  5. X Link Syntax • In HTML we use the <A> tag • In XML all tags can have a link <homepages xmlns:xlink="http://www.w3.org/1999/xlink"> <homepage xlink:type="simple" xlink:href="http://www.um.edu.mt"> University of Malta </homepage> </homepages>

  6. X Link Explanation • Declare the namespace in the top element <homepages xmlns:xlink="http://www.w3.org/1999/xlink"> • Define a simple element i.e. Go from the current position to that address. Multidirectional are not supported by most browsers. xlink:type="simple" xlink:href="http://www.um.edu.mt" • To define whether to use the current window or a new one ... xlink:show="new"

  7. Advanced X Links • XLink gets more interesting when we want to access remote locations as resources, instead of standalone pages • The value of the xlink:show attribute could have been set to "embed". This means that the resource should be processed inline within the page • With XLink, you can also specify WHEN the resource should appear • xlink:actuate="onLoad" specifies that the resource should be loaded and shown when the document loads • xlink:actuate="onRequest" means that the resource is not read or shown before the link is clicked. This is very handy for low-bandwidth settings

  8. X Pointer • XML Pointer Language • Allow hyperlinks to point to specific parts of an XML document • Uses XPath for navigation

  9. X Pointer Example • If a hyperlink points to an XML document we can add an XPointer after the URL href="http://www.example.com/cdlist.xml#id('rock').child(5)" • Find the element with unique Id rock • Point to the 5th item in the list

  10. X Pointer Short Hand href="http://www.example.com/cdlist.xml#id('rock') Is equivalent to href="http://www.example.com/cdlist.xml#rock

  11. X Path • Lies at the heart of the XML technologies • Is a syntax for defining parts of document • Uses path expressions to navigate • Contains a library of standard function (over 100) • Major element of XSLT

  12. X Path Nodes • Element • Attribute • Text • Namespace • Processing-instruction (<?xml version="1.0"?>) • Comment • Root node

  13. Node relationships • Parent • Children • Siblings • Ancestors • Descendants

  14. Example <?xml version="1.0" encoding="ISO-8859-1"?> <bookstore> <book> <title lang="eng">Harry Potter</title> <price>29.99</price> </book> <book> <title lang="eng">Learning XML</title> <price>39.95</price> </book> </bookstore>

  15. Usage

  16. Examples

  17. Example predicates

  18. Using Wildcards

  19. Selecting several paths

  20. Axes

  21. Location step • an axis (defines the tree-relationship between the selected nodes and the current node) • a node-test (identifies a node within an axis) • zero or more predicates (to further refine the selected node-set) axisname::nodetest[predicate]

  22. Location step example

  23. Absolute vrs Relative An absolute location path: /step/step/... A relative location path: step/step/... The difference is the initial /

  24. Programming example xmlDoc=new ActiveXObject("Microsoft.XMLDOM"); xmlDoc.async=false; xmlDoc.load("books.xml"); xpath="/bookstore/book[1]/title"; xmlDoc.selectNodes(xpath);

  25. X Query • Designed to query XML Data • Like SQL for databases • Built on XPath

  26. XQuery Example doc("books.xml")/bookstore/book/title Load the document and use XPath to get the data For more powerful queries use FLWOR expressions

  27. X Forms • Similar to HTML forms but defined in XML • Richer and more flexible • Platform and device independent • Standard in XHTML 2.0

  28. X Forms Example

  29. X Forms Result • The form • The XML • The Text

  30. XSL • XML Stylesheet Language • Consist of three parts • XSLT • Xpath • XSL-FO

  31. XSLT • XSL Transformations • Transforms XML to another XML document • Uses XPath to navigate • Most important part of XSL • Supported by most browsers

  32. Power • Add • Remove • Sort • Rearrange • Perform Tests • Make decisions • Hide • Etc ...

  33. Workings • Use XPath to define elements of source • When a match occurs • Transform the matching part into the resulting document

  34. Example CD Catalogue (XML) CD Catalogue (XSL) CD Catalogue (XML + XSL) Combined by adding the following line in the XML document <?xml-stylesheet type="text/xsl" href="cdcatalog.xsl"?>

  35. Declaration part of a Stylesheet <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

  36. <xsl:template> • XSL style sheet made up of different rules called templates • The Match attribute is used to associate a template to an element in the XML document

  37. Simple Template 1

  38. Simple Template 1 Result

  39. Simple Template 2

  40. Simple Template 2 Result

  41. Simple Template 3

  42. Simple Template 3 Result

  43. Simple Template 4

  44. Simple Template 4 Result

  45. Simple Template 5

  46. Simple Template 5 Result

  47. Simple Template 6

  48. Simple Template 6 Result

  49. Simple Template 7

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