XML processing in ColdFusion MX

1
XML processing in ColdFusion MX

• Everything you wanted to know about XML, but were
  afraid to ask
• October 2006 Jaxfusion User Group

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About the Presenter

• David Fekke
• Working with XML 1999
• Lead for Vurv HR-XML API

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Covered in this presentation

• Properly formed XML
• ColdFusion XML Tags and functions
• XPath queries
• XML XSDs and Validation
• XML Namespaces
• DOM vs. Streaming parsers
• StAX API

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XML

• eXtensible Markup Language
• Originated from SGML
• W3C standard
• More versatile then Flat files

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XML Syntax

• XML declaration
• lt?xml version"1.0" encoding"UTF-8"?gt
• Must have one root tag
• ltpreroottaggt lt/preroottaggt
• All tags must have closing tag.
• ltbr /gt single tags can have forward slash at the
  end
• lttag namevalue /gt tags can have attributes

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Pre MX XML features

• WDDX
• SOXML custom tag, windows only

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ColdFusion MX 6

• CFXML tag turns serialized XML into a ColdFusion
  object
• XMLParse() function
• ColdFusion XML Object works like series of
  structures and arrays
• XMLSearch() function
• XMLSearch Uses XPath queries to return array of
  XML nodes

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XML Check functions

• IsXML
• IsXmlDoc
• IsWDDX
• IsXmlAttribute
• IsXmlElem
• IsXmlNode
• IsXmlRoot

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XML editing functions

• XmlNew()
• XmlChildPos()
• XmlNew()
• XmlTransform()
• XmlElemNew()

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ColdFusion MX 7 Functions

• XmlGetNodeType()
• XmlValidate()

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XPath queries

• Provides a way to pull the elements you need
  without having to iterate through the entire DOM
• /rootelement/parent/childelement
• //childelement
• /rootelement/parentchildelement foo
• Used with XSLT templates

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XML Validation

• Define XML with DTD or XSD
• XSD preferred method for validation
• XSD uses an XML format
• Allows for strict and custom datatypes
• Allows for pattern recognition

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ltxsschema xmlnsxs"http//www.w3.org/2001/XMLSch
ema"gt ltxselement name"FirstName"
type"xsstring"/gt ltxselement name"LastName"
type"xsstring"/gt ltxselement name"Age"
type"xsstring"/gt ltxselement
name"customer"gt ltxscomplexTypegt ltxssequenc
egt ltxselement ref"FirstName"
/gt ltxselement ref"LastName"
/gt ltxselement ref"Age" /gt lt/xssequencegt
lt/xscomplexTypegt lt/xselementgt ltxselement
name"customers"gt ltxscomplexTypegt ltxssequen
cegt ltxselement ref"customer"
maxOccurs"unbounded" /gt lt/xssequencegt lt/xs
complexTypegt lt/xselementgt lt/xsschemagt
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lt?xml version"1.0" encoding"UTF-8"
?gt ltcustomersgt ltcustomergt
ltFirstNamegtDwightlt/FirstNamegt
ltLastNamegtMercerlt/LastNamegt ltAgegt32lt/Agegt
lt/customergt ltcustomergt
ltFirstNamegtMiguellt/FirstNamegt
ltLastNamegtCabreralt/LastNamegt ltAgegt33lt/Agegt
lt/customergt lt/customersgt
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Default XSD element types

• xsString
• xsnormalizedString
• xsinteger
• xsbase64Binary
• xsnegativeInteger
• xspositiveInteger
• xsHexbinary
• xsLong
• xsshort

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Custom Types
ltxsdsimpleType name"SKU"gt ltxsdrestriction
base"xsdstring"gt ltxsdpattern
value"\d3-A-Z2"/gt lt/xsdrestrictiongt
lt/xsdsimpleTypegt
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XML Namespaces

• Namespaces allow for XML to be segmented into
  different parts
• ltnamespaceelementName /gt namespace will prefix
  the element name
• ltfekkeroot xmlnsfekkehttp//www.fekke...
• No namespace xmlns
• Use explicit XPath with no namespace
• Nonamespace xpath/element

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DOM, SAX and Pull Parsers

• ColdFusion uses a DOM parser. Entire XML object
  in memory.
• SAX parser reads in file portion of the time.
  Raises events when elements match.
• StAX uses pull based parser to read one node at
  time. Uses streams to read in portion

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StAX

• BEA JSR 173
• Many implementations
• Includes Event and Pull parsers
• Jim Collins working on CFStAX library
• Woodstox library extremely fast implementation

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StAX objects

• XMLInputFactory
• XMLStreamConstants
• XMLStreamReader
• XMLEventReader

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XMLStreamConstants

• Constants for different node types
• XMLStreamConstants.START_ELEMENT
• XMLStreamConstants.END_ELEMENT
• XMLStreamConstants.START_DOCUMENT
• XMLStreamConstants.END_DOCUMENT

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XmlStreamReader methods

• Next() iterates through XML stream
• getLocalName() returns tag name
• getAttributeCount() returns tags attribute count
• getAttributeLocalName() returns attribute name
• getAttributeValue() returns attribute value
• hasText() returns boolean if element has text
• getText() returns element text

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Free XML Tools

• IE and Firefox have built in DOM parsers
• XMLFox for testing validation
• XMLButterfly for editing and formatting XML
• Dont use ALtova XML Spy, its crap!

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Summary

• Use XMLSearch instead of iterating through DOM
• Dont use cfsavecontent to build XML, use CFXML
• If using no namespace, use explicit xpaths
• Use xmlFormat or CDATA to handle special
  characters
• Use XSDs over DTDs

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Links

• http//www.w3.org/XML/
• http//www.w3.org/XML/Schema
• http//www.xml.com/
• http//coldfusion.sys-con.com/read/236002.htm

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Books

• ColdFusion Application Development
• Beginning XML (Programmer to Programmer)
• Oreilly XML in a Nutshell