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High-Tech Entrepreneurship Networking Event

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  1. XSLT I Robin Burke ECT 360

  2. Outline • XSLT processing • XSLT syntax • XPath • XSLT basics • Lab

  3. Admin • Announcement • Milestone #4

  4. Friday, October 21 5-7pm, CTI Collaboration Lab, Free Surf to www.depaulcti.com for more information high-techentrepreneurshipnetworking event Have you ever thought of using your IT skills to start your own company? Join other CTI students and alumni in exploring the possibilities. e, CTI’s new high-tech entrepreneurship club invites you to an open house to mingle, network, and learn. We will present info on DePaul’s New Venture (business plan) Competition, with $5,000 in prizes – and help you find teammates. Refreshments served.

  5. XML • XSL • "family" of standards • XSL-FO • formatting objects • typesetting • document = a set of geometric areas organized on pages • XSLT • transformations • XPath • supports both • a language for addressing individual XML nodes

  6. XSL-FO Example

  7. XSLT HTML example

  8. XSLT syntax • XML document • stylesheet • root element • templates • "rule-based" processing

  9. XSLT Processing • Let L be a list of nodes • Let T be a list of templates • style (L, T) = • Find a template t matching L • Instantiate t using L • May call style (L', T) • Return instantiated template • To process a document • style ( { root }, T )

  10. Special purpose • XSLT is not a general-purpose programming language • lacks many conventional facilities • technically a "tree-rewriting" language • XSLT 2.0 • is more general purpose

  11. Example <?xml version="1.0" encoding="UTF-8"?> <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"> <xsl:output method="html" version="4.0" encoding="UTF-8" indent="yes"/> <xsl:template match="/"> <html> <head> <title>Jeep suppliers</title> </head> <body>The first one is <xsl:value-of select="/child::entries/child::entry[position() = 1]/child::address/child::name/child::text()" /></body> </html> </xsl:template> </xsl:stylesheet>

  12. Note • stylesheet element • output type element

  13. Running example • value-of1

  14. XPath • XPath expression "/child::entries/child::entry[position() = 1]/child::address/child::name/child::text()" • How to read • "/" = root and delimiter for steps • axis::step = a move in the XML document • :: = "that is" or "that are" • [] = apply some predicate • position () = compute the position of this element in its list of siblings • text() = the element content • Result is a set of nodes

  15. Axes • self • this node • child • immediate descendant • descendant • any descendant • attribute • attribute list • following • siblings to the right • preceding • siblings to the left

  16. Steps • Depends on axis • element name • attribute name • can be associated with a predicate • foo[attribute::bar='5'] • entry[position() = 2]

  17. XPath shortcuts • Axes can be abbreviated • default = child • @ = attribute • // = descendant • . = self • .. = parent • Steps • text() can be omitted • [position() = n] can be [n] • Abbreviated version "/child::entries/child::entry[1]/child::address/child::name/child::text()" "/entries/entry[1]/address/name"

  18. Example • with simplified syntax

  19. XML Document

  20. Paths • All "name" elements? • All advertisers? • All non-advertisers? • The rating of the second entry? • All advertisers with a rating above 3? • The second line of every address?

  21. For-each • May want to operate on all nodes in a set • for-each element • instantiates contents once for every node in set

  22. Example • listing just names

  23. Multiple templates • Typically a stylesheet will have multiple templates • Easier to read / debug • Templates often correspond to elements • More modular

  24. Templates • template element • match attribute • describes nodes that use the template • content • template to instantiate • apply-templates element • select attribute • what nodes to use • position shows where in the parent element the result is inserted

  25. Example

  26. Whitespace • XSLT automatically removes whitespace • this is often correct • when it isn't • use text element

  27. Path mismatch • Biggest source of errors • end path has no content • Check path • local path • template match • apply-template select • Match/select should overlap by one step

  28. Example • template choice

  29. Building an element <xsl:element name="a"> <xsl:attribute name="href">http:// <xsl:value-of select="." /> </xsl:attribute> <xsl:value-of select="." /> </xsl:element> Becomes <a href="http://foo.org/">foo.org</a>

  30. Alternate syntax <a href="http://{.}"> <xsl:value-of select="." /></a> Becomes <a href="http://foo.org/">foo.org</a>

  31. Sorting • We can sort node lists • after they are selected • before they are operated on • for-each • apply-templates • Embed sort element

  32. Sorting, cont'd <xsl:apply-templates select="some/path"> <xsl:sort select="whatever/@foo" /> </xsl:apply-templates> What does this do?

  33. Example • complex selection and sorting

  34. Break / Lab

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