XSLT Design Patterns

1
XSLT Design Patterns
2
Stylesheet Design PatternsRef XSLT by Michael
KayISBN1-961005-06-7

• Four common design patterns for XSLT Stylesheets
• The majority of stylesheets fall into four major
  categories
• Fill-in-Blank Stylesheets
• Navigational stylesheets
• Rule-based stylesheets
• Computational stylesheets

3
Stylesheet Design Patterns

• Fill-in-Blank Stylesheets
• The template looks largely like a standard HTML
  file, sprinkled with a few extra control
  statements.
• Extra tags are used to retrieve variable data and
  insert it at a particular point in the HTML data
  page.
• The stylesheet has the same structure as the
  desired output.
• Fixed content is included directly in the
  stylesheet as text.
• Repeated sections (like rows in a table) can be
  enclosed by ltxslfor-eachgt tags.

4
Example 1

• Catalog.xml
• lt?xml version"1.0"?gt
• lt?xml-stylesheet type"text/css"
  href"booklists.css" ?gt
• ltBookCataloggt
• ltBookgt
• ltTitlegtBillions Of Starslt/Titlegt
• ltAuthorgtSusan Boggslt/Authorgt
• ltDategt1983lt/Dategt
• ltISBNgt1-5555-555-2lt/ISBNgt
• ltPublishergtAnderson-Wellslt/Publish
  ergt
• lt/Bookgt
• ltBookgt
• ltTitlegtAdventures Of Freddie the
  Froglt/Titlegt
• ltAuthorgtJohn Smithlt/Authorgt
• ltDategt1977lt/Dategt
• ltISBNgt0-444-4444-4lt/ISBNgt
• ltPublishergtKidder Publishing
  Co.lt/Publishergt

• Booklists.css
• BookCatalog displayblockbordersolid blue
• Book displayblock
• Title displayblock font-familyArialcolorRed
  
• Author displayblock
• Date,ISBN displaynone
• Publisher display block font-styleitalic

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Example 2 - Office.xml

• lt?xml version"1.0"?gt
• ltofficepersonnelgt
• ltpersongt
• ltnamegt Mary Jones lt/namegt
• lttitlegt CEO lt/titlegt
• ltreportsgt
• ltpersongt
• ltnamegt Susan Mills lt/namegt
• lttitlegt Director lt/titlegt
• ltreportsgt
• ltpersongt
• ltnamegt John Deen lt/namegt
• lttitlegt Engineer lt/titlegt
• lt/persongt
• lt/reportsgt
• lt/persongt
• ltpersongt
• ltnamegtDavid Smith lt/namegt
• lttitlegt Director lt/titlegt

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Example2 - Office.xsl

• lt?xml version"1.0"?gt
• ltxslstylesheet xmlnsxsl"http//www.w3.org/1999/
  XSL/Transform"
• version"1.0"gt
• ltxsltemplate match"/"gt
• lthtmlgtltheadgtlttitlegt Management lt/titlegtlt/headgt
• ltbodygt
• lttable border"2" cellpadding"5"gt
• lttrgt
• ltthgtNamegtlt/thgt ltthgtTitlelt/thgt ltthgt Reports
  To lt/thgt
• lt/trgt
• ltxslfor-each select"//person"gt
• lttrgt
• lttdgtltxslvalue-of select"name"/gtlt/tdgt
• lttdgtltxslvalue-of select"title"/gtlt/tdgt
• lttdgtltxslvalue-of select"ancestorperson1/n
  ame"/gtlt/tdgt
• lt/trgt
• lt/xslfor-eachgt
• lt/tablegt
• lt/bodygt

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Stylesheet Design Patterns

• Navigational Stylesheets
• Is essentially output-oriented.
• Named templates can be used as subroutines to
  perform some of the commonly-needed tasks.
• Looks more like a conventional procedural program
  with variables, conditional statements, loops
  and subroutine calls.
• Often used to produce reports on data-oriented
  XML documents, where the structure of the source
  document is regular and predictable.

8
Example

• Example on slide 9
• The example shows BookSales.xml and BookSales.xsl
  that generates an HTML output showing book sales
  by month.

9
Example

• BookSales.xml
• lt?xml version"1.0"?gt
• lt?xml-stylesheet type"text/xsl"
  href"011231.xsl"?gt
• ltsalesgt
• ltsummarygt
• ltheadinggtBook Storelt/headinggt
• ltsubheadgtSales Reportlt/subheadgt
• ltdescriptiongtSales Report for two
  monthslt/descriptiongt lt/summarygt
• ltdatagt
• ltmonthgtltnamegtJanuary 2002lt/namegt ltweek number"1"
  books_sold"1000" /gt
• ltweek number"2" books_sold"2000" /gt
• ltweek number"3" books_sold"3000" /gt
• ltweek number"4" books_sold"4000" /gt
• lt/monthgt
• ltmonthgt
• ltnamegt April 2002lt/namegt
• ltweek number"1" books_sold"700" /gt
• ltweek number"2" books_sold"2000" /gt
• ltweek number"3" books_sold"1000" /gt

• BookSales.xsl
• lt?xml version"1.0"?gt
• ltxslstylesheet xmlnsxsl"http//www.w3.org/1999/
  XSL/Transform" version"1.0"gt
• ltxsloutput method"html"/gt
• ltxsltemplate match"/"gt
• ltHTMLgt
• ltBODYgt
• ltxslvariable name"Space" select"' '"/gt
• ltxslfor-each select"//data/month"gt
• ltbr/gtltxslvalue-of select"name"/gt
• ltxslvalue-of select"Space"/gt
• ltxslvalue-of select"format-number(sum(week/_at_boo
  ks_sold), ',')"/gt
• lt/xslfor-eachgt
• lt/BODYgt
• lt/HTMLgt
• lt/xsltemplategt
• lt/xslstylesheetgt

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Stylesheet Design Patterns

• Rule-based Stylesheets
• Consists primarily of rules describing how
  different features of the source document should
  be processed.
• The stylesheet is not structured according to the
  desired output layout.
• Makes minimal assumptions about the structure of
  the source or the result documents.
• Are most useful when processing source documents
  whose structure is flexible or unpredictable, or
  which may change a lot in the future.

11
Example

• Example shown on slides 12,13 and 14.
• In this example, the stylesheet, BookCatalog.xsl
  generates a file called BookCatalog.xml (slide
  14) from the input file, ProductCatalog.xml (on
  slide 12), using template rules.

12
Example ProductCatalog.xml

• lt?xml version"1.0"?gt
• ltcataloggt
• ltproduct code"1234" category"tools"gt
• ltdescriptiongtHammerlt/descriptiongt
• ltweight units"lbs"gt0.5lt/weightgt
• ltpricegt12.00lt/pricegt
• lt/productgt
• ltproduct code"0000" category"tools"gt
• ltdescriptiongtNutlt/descriptiongt
• ltweight units"lbs"gt0.1lt/weightgt
• ltpricegt2.00lt/pricegt
• lt/productgt
• ltproduct code"7777" category"tools"gt
• ltdescriptiongtBoltlt/descriptiongt
• ltweight units"lbs"gt0.1lt/weightgt
• ltpricegt1.00lt/pricegt
• lt/productgt
• ltbookgt
• lttitlegtCosmoslt/titlegt

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BookCatalog.xsl

• lt?xml version"1.0"?gt
• ltxslstylesheet xmlnsxsl"http//www.w3.org/1999/
  XSL/Transform"
• version"1.0"gt
• ltxsloutput method"xml"/gt
• ltxsltemplate match"/"gt
• ltxslapply-templates/gt
• lt/xsltemplategt
• ltxsltemplate match"catalog"gt
• ltxslelement name"BookCatalog"gt
• ltxslapply-templates/gt
• lt/xslelementgt
• lt/xsltemplategt
• ltxsltemplate match"book"gt
• ltxslelement name"book"gt
• ltxslapply-templates/gt
• lt/xslelementgt
• lt/xsltemplategt

• ltxsltemplate match"title"gt
• ltxslelement name"title"gt
• ltxslvalue-of select"."/gt
• lt/xslelementgt
• lt/xsltemplategt
• ltxsltemplate match"author"gt
• ltxslelement name"author"gt
• ltxslvalue-of select"."/gt
• lt/xslelementgt
• lt/xsltemplategt
• ltxsltemplate match"text()"gt
• lt/xsltemplategt
• lt/xslstylesheetgt

14
BookCatalog.xml

• lt?xml version"1.0" encoding"utf-8"?gt
• ltBookCataloggtltbookgtlttitlegtCosmoslt/titlegtltauthorgtSa
  ganlt/authorgtlt/bookgtltbookgtlttitlegtXML Made
  Easylt/titlegtltauthorgtJoe Bloggslt/authorgtlt/bookgt
• lt/BookCataloggt

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Stylesheet Design Patterns

• Computational Stylesheets
• Are the most complex of the four design patterns.
• They are used when there is a need to generate
  nodes in the result tree that do not correspond
  directly to nodes in the source tree.
• Examples
• A comma-separated list of items in the source are
  to be displayed as bulleted list of output.
• Using complex aggregation of data
• Use functional programming concepts and recursion
  to accomplish the tasks.

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Examplecalc.xsl

• lt?xml version"1.0"?gt
• ltxslstylesheet xmlnsxsl"http//www.w3.org/1999/
  XSL/Transform"
• version"1.0"gt
• ltxsloutput method"html"/gt
• ltxsltemplate match"/"gt
• lthtmlgtltheadgtlttitlegtCalculationlt/titlegtlt/he
  adgt
• ltbodygt
• 16 / 2
• ltxslvariable name"result"gt
• ltxslcall-template
  name"NumDiv2"gt
• ltxslwith-param name"N"
  select"16"/gt
• lt/xslcall-templategt
• lt/xslvariablegt
• ltxslvalue-of select"result"/gt
• lt/bodygt
• lt/htmlLgt
• lt/xsltemplategt
• ltxsltemplate name"NumDiv2"gt