XSLT and ColdFusion

1
XSLT and ColdFusion

• Whipping Your XML Data Into Shape

Matt Woodward Dallas/Fort Worth CFUG September 7,
2004
2
Who Am I?

• Web application developer for i2 Technologies
• Consulting/contract work through my company Sixth
  Floor Software
• Member of Team Macromedia for ColdFusion
• Working with CF since 1996
• Also develop in PHP and Java

3
What Ill Be Covering

• Extensible Stylesheet Language Transformations
  (XSLT) Introduction and basic concepts
• Manipulating XML data using XSLT
• Support for and use of XSLT in ColdFusion MX
• Based on article appearing in August 2004 edition
  of ColdFusion Developers Journal

4
XML Its Everywhere

• Like it or not, XML is everywhere these days (web
  services, news service and blog datafeeds,
  application configuration files)
• If you havent had to deal with XML yet, dont
  worry you will
• XML is plain text, but it is infinitely more
  usable than comma or tab-delimited text data

5
Why Use XML?

• Data exchange, particularly when security is a
  concern
• Because I said so XML may be the only way
  youll be able to receive or send data (Wal-Mart,
  HIPPA, FERPA)
• May make better sense than traditional RDBMS in
  some cases

6
XML A Brief Example
lt?xml version"1.0" encoding"utf-8"?gt ltanimalsgt
ltanimal species"Feline" subspecies"Lion"gt
ltnamegtRoarylt/namegt
ltsexgtFemalelt/sexgt ltcolorgtFawnlt/colorgt
ltweightgt325 poundslt/weightgt
ltfeedingTimegt1400lt/feedingTimegt lt/animalgt
ltanimal species"Reptile" subspecies"Tortoise"gt
ltnamegtShellylt/namegt lttypegtBox
Turtlelt/typegt ltsexgtFemalelt/sexgt
ltcolorgtGreenlt/colorgt ltweightgt20
poundslt/weightgt ltfeedingTimegt1500lt/feedin
gTimegt lt/animalgt lt/animalsgt
7
Transforming XML

• XML data is of limited use by itself
• Web services you may find one that gives you the
  data you want, but not in the right format
• Data exchange different companies require
  different formats (schemas) of XML data
• Data reuse presenting data in different forms to
  different users or devices

8
Whats XSLT?

• Extensible Stylesheet Language Transformations
  (XSLT) is designed to transform XML data from one
  form into another
• Uses stylesheets to define how XML data is to
  be transformed
• XSLT is itself a flavor of XML, meaning XSLT
  stylesheets meet all the requirements of XML
  (well-formed, etc.)
• XSLT is a language, so it has many familiar
  language constructs (conditionals, loops)

9
Basic XSLT Concepts

• XSLTs core purpose modifying XML documents
  based on pattern matching
• Pattern matching is defined in XSLT stylesheets
  using XPath syntax
• XSLT stylesheets are typically just a set of
  transformation rules
• XSLT is processed by an XSLT processor (in CFMXs
  case this is Apache Xalan)
• Similar to regular expressions with plain text,
  only far more flexible, elegant, and powerful

10
How XSLT is Processed
Source http//www.objectsbydesign.com/projects/xm
i_to_html.html
11
The Sample Scenario

• Youre the web developer for your local zoo
• You need to display a list of animals as HTML
• The catch the only way the DBA will give you the
  data is as XML
• What do you do???

12
One Option Be Lazy

• Output the XML directly to the browser

13
A Better Option XSLT

• Use XSLT to transform the XML data into HTML
• Many modern browsers support in-browser XML/XSLT
  transformations, but compatibility may vary even
  if the functionality is available (IE 5 is
  terrible, IE 6 is slightly better, Netscape 6 is
  OK, and Netscape 7 fully supports the W3C specs)
• Better to do the transformation on the server
  where you have more control

14
Anatomy of a Stylesheet

• XSLT is based on pattern matching
• Our task create a stylesheet and give it
  instructions to execute when it finds matching
  patterns in the XML data
• For now, well present the data in the order its
  received (well do some other cool stuff later)

15
Our First Stylesheet

• animalsHtml.xsl
• ltxslstylesheetgt - required declaration
• ltxsloutputgt - tells processor how to output data
  (available options vary by processor, but W3C
  standard options are xml, html, and text)
• ltxsltemplate match/animalsgt - tells XSLT
  processor to start at the top of the XML and find
  the ltanimalsgt element
• XSLT instructions are defined using XPath, which
  according to the W3C is a language for
  addressing parts of an XML document

16
Retrieving the Details

• ltxslfor-each selectanimalgt - looping
  instruction instructions are executed for each
  ltanimalgt element
• could have used another ltxslapply-templatesgt
  instruction here, but this isnt compatible with
  what were doing to be doing momentarily
• ltxslvalue-ofgt - retrieves particular pieces of
  data _at_ used to indicate an attribute as opposed
  to an element

17
Functional Comparison
CFML query output
ltcfoutput querygetAnimalsgt lttrgt
lttdgtspecieslt/tdgt lttdgtsubspecieslt/tdgt
lttdgtnamelt/tdgt lt!--- etc. ---gt
lt/trgt lt/cfoutputgt
XSLT for-each
ltxslfor-each selectanimalgt lttrgt
lttdgtltxslvalue-of select_at_species /gtlt/tdgt
lttdgtltxslvalue-of select_at_subspecies /gtlt/tdgt
lttdgtltxslvalue-of selectname /gtlt/tdgt
lt!-- etc. --gt lt/trgt lt/xslfor-eachgt
18
Now for the easy part ...

• Use CF to apply the XSLT stylesheet to the XML
  data and output the results in three easy steps

1. Read in the XML data ltcffile actionread
fileExpandPath(.)/animals.xml
variableanimalsXml /gt 2. Read in the XSLT
stylesheet ltcffile actionread
fileExpandPath(.)/animalsHtml.xsl
variableanimalsXsl /gt 3. Use XmlTransform()
to transform the data ltcfoutputgtXmlTransform(anim
alsXml, animalsXsl)lt/cfoutputgt
19
A More Sophisticated Transformation

• Were outputting XML as HTML, but we can make
  this data more useful
• Next step create a feline-only listing, ordered
  by feeding time

20
Stylesheet 2

• ltxslsort selectfeedingTime /gt - tells the
  XSLT processor to perform an ascending sort on
  the elements within the for-each loop based on
  the ltfeedingTimegt element
• ltxslif test_at_speciesFelinegt - if species
  Feline, output otherwise ignore
• no ltxslelsegt command, but ltxslchoosegt,
  ltxslwhengt and ltxslotherwisegt can be used to
  create a switch

21
Things to Know ...

• XSLT is based on the design of functional
  languages such as Lisp, Scheme, and Haskell
  biggest point here is that variables are
  immutable
• Loops in XSLT arent really loops, its
  actually either iteration (do something for each
  instance of something) or recursion (function
  calls itself until a condition is met)

22
Uses of XSLT

• Presenting the same XML data different ways to
  different users or clients (e.g. PC web browser,
  WAP/wireless device, etc.)
• Data exchange (can manipulate data from one
  schema to another, system compatibility isnt an
  issue)
• Great way to keep data presented on the web 100
  separate from presentation
• Great way to reuse data (same data can be used
  for online display, sent to printing devices,
  etc.)

23
XSLT Is/Is Not ...

• XSLT IS a powerful companion to XML, allowing for
  easy searching, manipulation, and transformation
  of XML data. If youre using XML and youre not
  using XSLT, youre probably doing things the hard
  way!
• XSLT is NOT a replacement for CSS--these two
  technologies were designed to serve two
  completely different purposes

24
Resources

• Official W3C spec http//www.w3.org/TR/xslt
• xml.com Introduction to XSLT http//www.xml.com/p
  ub/a/2000/08/holman/
• Online XSLT Reference/API http//www.zvon.org/xxl
  /XSLTreference/Output/
• Basic Tutorial http//cozan.com/books/books/xml/x
  slt/ch01_01.htm
• XSLT by Doug Tidwell (OReilly)
• XSLT Cookbook by Sal Mangano (OReilly)
• XSLT 2.0 Programmers Reference by Michael Kay
  (Wrox)

25
QA
Thanks!