Introduction BCi

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Introduction BCi
XSLT
MC 365 Software Engineering
Presented by John Ristuccia Shawn Posts Ndi
Sampson
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Title EE and DC
What can BCi Do?
Background

• What is XSLT?
• XSLT stands for Extensible Stylesheet Language
  Transformations
• XSLT is designed for use as part of XSL, which is
  a stylesheet language for XML.
• What is XML and why does it need XSL
• Extensible Markup Language is a set of semantic
  rules designed to break up a document into
  hierarchical and easily identifiable parts.
• XML Has three important features

3
Title EE and DC
What can BCi Do?
Background Continued

• XML is a meta-markup language
• Instead of having a specified set of tags to draw
  from, you define your own as you need them
  allowing for immense versatility and
  Domain-specific markup languages.
• XML Follows a Strict hierarchical structure.
• Every well-formed XML document is a tree having
  a root, children, and leaves. Nodes can be
  elements, text, attributes, comments, processing
  instructions, or namespaces.
• XML contains only structural and semantic info
• XML documents contain no formatting information
  hence XSL/XSLT.

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What can BCi Do?
Title EE and DC
Background Continued

• To Reiterate
• XSL (Extensible Stylesheet Language) provides a
  language for adding formatting and structure to
  an XML document. The process of XSL
  Transformation basically takes in one XML
  document and transforms it into a different XML
  document (usually but not always a well-formed
  HTML document viewable by a web browser)

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What can BCi Do?
Title EE and DC
Advantages and Disadvantages

• Advantages
• Easy to merge data into XML data into a
  presentation
• More resilient to change in the details of the
  XML document than in the low-level DOM (Document
  Object Model) and SAX (Simple API for XML)
• Database inquiries can be returned in XML
• Insensitive to column order
• Disadvantages
• Memory intensive and suffers a performance
  penalty
• Difficult to implement complicated business
  rules
• Have to learn a new language
• Cant change the value of variables (requires
  recursion)

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Title EE and DC
What can BCi Do?
XSL Transformations

• Use
• X-Path to identify (select) parts of an XML
  document
• XSLT Templates to apply transformations
• Requires
• Well formed XML document
• XSL document (stylesheet) that contains
  formatting and transformation templates
• XSLT parser to perform the transformations

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Title EE and DC
What can BCi Do?
Steps for Translating a Document

• Tell a system which parser to use
• Establish a factory in which to create
  transformations
• Create a transformer for a particular style sheet
• Invoke the transformer to process the document

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Who can use BCi?
Title EE and DC
XSLT Example
lt- XML
lt- XSL
XSLT -gt
Another example
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Title EE and DC
What can BCi Do?
XSLT Stylesheet Elements

• Matching and Selecting Templates
• xsltemplate
• xslapply-template
• xslvalue-of
• Branching Elements
• xslfor-each
• xslif
• xslchoose

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Title EE and DC
What can BCi Do?
Example of xslif

• xslif test expression
• Evaluate the expression to a boolean and if
  true, applies the template body
• XSLT has not else if construct (use choose)
• ltxsltemplate match ROWgt
• lt!-- select first node in the node set --gt
• ltxslif test position() first()gt
• ltxslvalue of select . /gt
• lt/xslifgt
• lt/xsltemplategt
• ltxsltemplate match ROWgt
• lt! Select if current node has children --gt
• ltxslif test node()gt
• ltxslapply-templates/gt
• lt/xslifgt
• lt/xsltemplategt

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Requirements?
Title EE and DC
Some Simple XSLT

• Copying
• xslcopy, copies the current node
• xslapply-templates, processes the children of
  the current node
• ex. ltxslstylesheetxmlnsxsl"http//www.w3.org/1
  999/XSL/Transform" version"1.0"gt
• ltxsltemplate match"title"gt
• ltxslcopygt
• ltxslapply-templates/gt
• lt/xslcopygt
• lt/xsltemplategt
• lt/xslstylesheetgt
• xslcopy-of element, can copy the entire subtree
  of each node that the template selects
• ex. ltxsltemplate match"titlegt
• ltxslcopy-of select""/gt
• lt/xsltemplategt

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Potential Problems?
Some More Simple XSLT

• Deleting
• ltxsltemplate match"nickname"gt
• lt/xsltemplategt
• ltxsltemplate match"project_at_status'canceled'"gt
  lt/xsltemplategt

• While a match value of "project" would delete all
  the project elements from the output, the match
  value shown will only delete project elements
  whose status attributes have the string
  "canceled" as their value.

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Some More Simple XSLT

• Changing Element Names
• ex.
• ltxsltemplate match"article"gt
• lthtmlgt
• ltxslapply-templates/gt
• lt/htmlgt
• lt/xsltemplategt
• This template rule tells an XSLT processor to
  take any article element fed to it as input,
  and output its contents surrounded by html tags