XSLT for Data Manipulation

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XSLT for Data Manipulation

• By April Fleming

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What We Will Cover

• The What, Why, When, and How of XSLT
• What tools you will need to get started
• A sample Hello World application
• Enough XSLT Constructs to get started, given from
  a ColdFusion point-of-view

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What is XSLT

• eXstensible Stylesheet Language Transformations
• Transformation Language
• High-Level data manipulation language
• A language for transforming the structure of an
  XML document
• Primarily designed by the W3C for transforming
  one XML document into another

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What is XSLT - contd

• The XSLT language is expressed as a well-formed
  XML document
• The XSLT language belongs to the XSLT Namespace
• An XSLT transformation describes rules for
  transforming a source tree into a result tree.
  This set of rules is called a stylesheet

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What is XSLT - contd

• These rules have two parts
• Pattern
• Matched against nodes in the source tree
• Template
• Can be instantiated to form part of the result
  tree

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What is XSLT - contd

• The result tree is separate from the source tree
• The result tree can be in a completely different
  form from the source tree

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Output Formats

• ltxsloutputgt
• Optional
• Parser will default the output type if the tag is
  omitted.
• Top-Level Element used to define the output type
  desired
• Enables you to specify encoding for output

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Output Format - contd

• Three types of output
• XML
• ltxsloutput methodxml /gt
• output is an XML document or XML document
  fragment
• lt?xml version"1.0"?gt appears in the resulting
  output

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Output Formats - Contd

• HTML
• ltxsloutput methodhtml version4.0 /gt
• Output is an HTML document
• Text
• Allows output in many other text-based formats
• Comma-seperated values
• RTF
• PDF
• EDI
• SQL
• Javascript

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Why would I use XSLT

• XSLT is a supported w3c standard.
• XSLT Provides the traditional language
  conventions that we are used to when processing
  data
• Looping
• Conditional Logic
• Expressions
• Variables

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Why would I use XSLT - contd

• Dynamic
• Efficient
• Facilitate separation of Data and Presentation

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How I used XSLT and Why

• Distributed Search Application
• I needed to write a search engine that could
  function independent of the various search
  interfaces that we had.
• I needed the engine to be completely independent
  of the search interfaces or the search result
  displays.

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How I used XSLT and Why

• I chose XML as the data format for I/O to the
  engine
• Uniform structure of Data regardless of the
  source
• Data could be easily parsed using XML parser

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How I used XSLT and Why - contd

• I chose XSLT to process the XML data going into
  and out of the search engine
• With XSLT I could easily transform the data
  defintion output packets from the engine and
  create an html search form
• I also found XSLT to be a great way to take the
  search results and transform them into the
  various display formats we offered to our users

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When would I use XSLT?

• When you have XML data from a source (external or
  internal) with no other way to process that data
• When the XSLT transformations are faster than the
  current way you have to process your XML data.
• Example XSLT vs. CF processing
• When you need more power and flexibility than
  your current XML processing mechanism provides
• Example CF MX XML Processing Tags/Functions

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What tools will I need to use XSLT?

• XML Parser
• MSXML
• This is the Parser that I used
• Free download from Microsoft
• Excellent Documentation
• http//msdn.microsoft.com/xml/default.asp
• Other Parsers - see chart on next slide
• Good understanding of XPath
• Used for XSLT expressions
• MSXML SDK - good Xpath documentation

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• XML Parser Comparison Chart

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Simple Hello World example

• To perform a transformation we need three
  things
• XML Data
• XSLT Stylesheet
• XML Parser

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• XML Data - Save as hello.xml
• lt?xml version"1.0" ?gt
• ltoutputgtHello Worldlt/outputgt

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• XSLT Stylesheet Save as hello.xsl
• ltxslstylesheet xmlnsxsl"http//www.w3.org/1999/
  XSL/Transform" version"1.0"gt
• ltxsltemplate match/gt
• lthtmlgt
• ltheadgt
• lttitlegt XSLT Examplelt/titlegt
• lt/headgt
• ltbodygt
• ltxslvalue-of selectoutput /gt
• lt/bodygt
• lt/htmlgt
• lt/xsltemplategt
• lt/xslstylesheetgt

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Parsing ColdFusion MSXML Parserlt!---Create
two instances of the XML Parser, one for the XML
and one for the XSL---gtltcfobject type "COM"
action "create" class "MSXML2.DOMDOCUMENT.4.
0" name "xml"gt ltcfobject type "COM"
action "create" class "MSXML2.DOMDOCUMENT.4.
0" name "xsl"gt
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ltcfscriptgt //do not validate the
xml xml.validateOnParsefalse xml.async
false //load the xml file into the xml instance
of the parser temp xml.load("c\inetpub\wwwroot
\hello.xml")lt/cfscriptgtltcfscriptgt xsl.asyncfa
lse //load the xsl file into the xsl instance
of the parser xsl.load("c\inetpub\wwwroot\hello.
xsl") output xml.transformNode(xsl)lt/cfscr
iptgtlt!---output the transformed
result----gtltcfoutputgtoutputlt/cfoutputgtlt!---se
t com objects to null---gtltcfset xml ""gtltcfset
xsl ""gt
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• XSLT Stylesheet Structure
• The XSLT namespace has the URI
  http//www.w3.org/1999/XSL/Transform.
• ltxslstylesheetxmlnsxsl"http//www.w3.org/1999/X
  SL/Transform" version"1.0"gt
• Remember that an XSLT stylesheet is a well-formed
  XML document, therefore you must always include
  the corresponding closing tag.
• lt/xslstylesheetgt
• The tag ltxsltransformgt is a synonym for
  ltxslstylesheetgt either one is acceptable

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XSLT Stylesheet Structure - contd

• Can use any prefix, provided that there is a
  namespace declaration that binds the prefix to
  the URI of the XSLT namespace
• An element occurring as a child of an
  xslstylesheet element is called a top-level
  element

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Top Level Elements

• ltxslimport href"..."/gt
• ltxslinclude href"..."/gt
• ltxslstrip-space elements"..."/gt
• ltxslpreserve-space elements"..."/gt
• ltxsloutput method"..."/gt
• ltxslkey name"..." match"..." use"..."/gt
• ltxsldecimal-format name"..."/gt

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Top Level Elements - contd

• ltxslnamespace-alias stylesheet-prefix"..."
  result-prefix"..."/gt
• ltxslattribute-set name"..."gtlt/xslattribute-setgt
  
• ltxslvariable name"..."gt...lt/xslvariablegt
• ltxslparam name"..."gt...lt/xslparamgt
• ltxsltemplate match"..."gtlt/xsltemplategt
• ltxsltemplate name"..."gtlt/xsltemplategt

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Templates

• ltxsltemplate matchgt
• Match is a pattern, the pattern is expressed
  using Xpath
• Pattern describes which nodes in the source tree
  the template rule matches
• ltxsltemplate match/ gt
• matches the root node
• ltxsltemplate matchTitle gt
• matches the title node

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Templates - contd

• ltxsltemplate matchChapter/Titlegt
• matches the Title node that is a child to the
  Chapter node
• ltchaptergt
• lttitlegtMy Titlelt/titlegt
• lt/chaptergt

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Templates - contd

• ltxsltemplate matchChapter/_at_titlegt
• matches the title attribute of the chapter node
• ltchapter titlemy title
• lt/chaptergt

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Templates - contd

• When the template is instantiated (a match
  condition is met), the instructions within the
  template tags are executed and the resulting data
  is copied to the result tree.
• ltxsltemplate match/gt
• .instructions.
• lt/xsltemplategt

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ltxslapply-templatesgt

• For each child of the current node
• Find the matching template rule
• Instantiate the template rule
• ltxsltemplate match/gt
• ltxslapply-templates/gt
• lt/xsltemplategt

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ltxslapply-templates selectgt

• Allows you to control the order that template
  rules are applied
• ltxsltemplate match/gt
• ltxslapply-templates selectapples/gt
• ltxslapply-templates selectoranges/gt
• ltxslapply-templates selectbanannas/gt
• lt/xsltemplategt

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ltxslvalue-ofgt

• Extract the required information from the node
  directly
• ltxsltemplate match/gt
• lthtmlgt
• ltheadgtlt/headgt
• ltbodygt
• ltxslvalue-of selectoutput/gt
• lt/bodygt
• lt/htmlgt
• lt/xsltemplategt

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ltxslfor-eachgt - Looping

• XSLT
• ltxslfor-each selectorangesgt
• lt/xslfor-eachgt

• ColdFusion
• ltcfloop listorangesgt
• lt/cfloopgt

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ltxslifgt - Conditional Logic

• XSLT
• ltxsltemplate match"name"gt
• ltxslvalue-of select./gt
• ltxslif test"position()!last()"gt
• ,
• lt/xslifgt
• lt/xsltemplategt

• ColdFusion
• ltcfset pos0gt
• ltcfloop listnamesIndexnamegt
• ltcfset posincrementValue(pos)gt
• name
• ltcfif pos neq listlen(names)gt
• ,
• lt/cfifgt
• lt/cfloopgt

Result Bob, Mary, John, Martha, Sue
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ltxslchoosegt - Conditional Logic

• XSLT
• ltxsltemplate match"order"gt
• ltxslchoosegt
• ltxslwhen test"total lt 5"gt
• (small)
• lt/xslwhengt
• ltxslwhen test"total lt 10"gt (medium)
• lt/xslwhengt
• ltxslotherwisegt
• (large)
• lt/xslotherwisegt
• lt/xslchoosegt
• lt/xsltemplategt

• ColdFusion
• ltcfswitch expressionordergt
• ltcfcase value1,2,3,4gt
• (small)
• lt/cfcasegt
• ltcfcase value5,6,7,8,9gt
• (medium)
• lt/cfcasegt
• ltcfdefaultcasegt
• (large)
• lt/cfdefaultcasegt
• lt/cfswitchgt

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ltxslvariablegt - Variables

• XSLT
• ltxslvariable name"n" select"2"/gt ...ltxslv
  alue-of select"itemn"/gt
• ColdFusion
• ltcfset n2gt
• listgetat(list,n)
• Variables may be defined Globally or Locally
• Local variables can be defined within a template
  body

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Datatypes

• Variables are not statically typed, rather they
  take whatever type of value is assigned to them,
  just as ColdFusion does
• String
• Number
• Boolean
• Node-Set
• A set of nodes in the source tree
• Tree

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Expressions

• Syntax of expressions is defined by the XPath
  Recommendation
• Used as attribute values for many XSLT elements
• ltxslvalue-of select(x y) 2/gt

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Resources

• XSLT Programmers Reference by Michael Kay
  (Wrox)
• W3C
• http//www.w3c.org
• Microsoft MSXML SDK Documentation
• http//msdn.microsoft.com/library/default.asp?url
  /library/en-us/xmlsdk/htm/sdk_intro_6g53.asp
• XSL-List
• http//www.mulberrytech.com/xsl/xsl-list
• I have relied heavily on these resources not
  only for the application development I have done,
  but also in preparation for this presentation.
  Many of the information and examples come from
  one of these sources.