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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 - cont’d 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 - cont’d 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 - cont’d 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 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 - cont’d Three types of output XML output is an XML document or XML document fragment appears in the resulting output
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Output Formats - Cont’d HTML 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 - cont’d 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 - cont’d 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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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 What tools will I need to use XSLT?
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XML Parser Comparison Chart
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To perform a transformation we need three things XML Data XSLT Stylesheet XML Parser Simple “Hello World” example
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XML Data - Save as hello.xml Hello World
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XSLT Stylesheet – Save as hello.xsl XSLT Example
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Parsing – ColdFusion & MSXML Parser
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//do not validate the xml xml.validateOnParse=false; xml.async = false; //load the xml file into the xml instance of the parser temp = xml.load("c:\inetpub\wwwroot\hello.xml"); xsl.async=false; //load the xsl file into the xsl instance of the parser xsl.load("c:\inetpub\wwwroot\hello.xsl"); output = xml.transformNode(xsl); #output#
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XSLT Stylesheet Structure The XSLT namespace has the URI http://www.w3.org/1999/XSL/Transform. http://www.w3.org/1999/XSL/Transform Remember that an XSLT stylesheet is a well-formed XML document, therefore you must always include the corresponding closing tag. The tag is a synonym for either one is acceptable
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XSLT Stylesheet Structure - cont’d 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 xsl:stylesheet element is called a top- level element
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Top Level Elements
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Top Level Elements - cont’d...
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Templates “Match” is a pattern, the pattern is expressed using Xpath Pattern describes which nodes in the source tree the template rule matches matches the root node matches the title node
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Templates - cont’d matches the Title node that is a child to the Chapter node My Title
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Templates - cont’d matches the title attribute of the chapter node <chapter title=”my title” …
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Templates - cont’d 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. ….instructions….
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For each child of the current node Find the matching template rule Instantiate the template rule
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Allows you to control the order that template rules are applied
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Extract the required information from the node directly …
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- Looping XSLT: … ColdFusion: …
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- Conditional Logic XSLT:, ColdFusion: #name#, Result: Bob, Mary, John, Martha, Sue
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- Conditional Logic XSLT: (small) (medium) (large) ColdFusion: (small) (medium) (large)
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- Variables XSLT:... ColdFusion: #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
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Resources XSLT – Programmer’s 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 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.
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