Processing XML/CDA Documents - Health Level … Paul V. Biron, Processing XML/PRA Documents: DOM, SAX and XSL 4 XSL • Alphabet Soup – XSL - Exstensible Stylesheet Language –

ProcessingXML/CDA Documents

Paul V. Biron, MLISKaiser Permanente, So Cal Medical Group

Pasadena, CA

Co-Chair HL7 XML SIGCo-Chair HL7 Structured Document TC

HL7 Fall Plenary MeetingSept 14, 2000

XSL(T), DOM and SAX

2000-05-22 Paul V. Biron, Processing XML/PRA Documents: DOM, SAX and XSL

2

Intro

• Extensible Stylesheet Language (XSL)– XSL Transformation Language (XSLT)

– XML Path Language (XPath)

– CDA Transformation Issues

• Document Object Model (DOM)

• Simple API for XML (SAX)

• Namespaces in XML [optional]

Extensible Stylesheet Language


4

XSL

• Alphabet Soup– XSL - Exstensible Stylesheet Language– XSLT - XSL Transformation Language– XPath - XML Path Language

• XSL can be used to:– Generate XHTML

– Generate other XML

– Generate the XSL formatting language as ahierarchical sequence of formatting objects

• images, text lines, paragraph blocks ,etc.


5

XSL: Generate XHTML

XSLT transformation

XSLstylesheet

XMLdoc-

ument

XHTMLdoc-

ument


6

XSL: XSLT

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

<xsl:template match=’pattern’>{action}

</xsl:template>

<xsl:template match=’pattern’>{action}

</xsl:template></xsl:stylesheet>

XSL Document


7

XSL: Formatting Objects (FOs)

• Pagination and Layout Formatting Objects

• Block Formatting Objects

• Inline Formatting Objects

• Formatting Objects for Tables

• Formatting Objects for Lists

• Link and Multi Formatting Objects

• Out-of-Line Formatting Objects


8

XSL: Generate Formatting Objects

XSLT transformation

XSL formattingengine

Consists of the tags andattributes which representspecifications for the XSLformating engine

Output to display,printer, Postscript, etc.

XSLstylesheet

XMLdoc-

ument

XSLFOs


9

Radiology Report

Patient Information• Name: Henry Levin, the 7th• MRN: 123456789• SEX: Male• DOB: May 13, 1923

Procedure : Chest X-RayDate: November 07, 1999

Clinical DataHistory of smoking for 40 years.

FindingsRLL nodule.

ImpressionsRLL nodule, suggestive of malignancy.Compared with a prior CXR from 6 monthsago, nodule size has increased.

RecommendationsI notified the ordering physician of this findingby phone.

<RadiologyReport> <Header> <Name> Henry Levin, the 7th </Name> <MRN>123456789</MRN> <SEX>Male</SEX> <DOB>May 13, 1923</DOB> <PROCEDURE>Chest X-Ray <ID code="P5-20100" system="SNOMED"/> <DATE> November 07, 1999 </DATE> </PROCEDURE> </Header> <Body> … </Body></RadiologyReport>

Locally applied markup

Transformation Use-cases


10

<levelone> <clinical_document_header> <clinical_document_header.service_cd V="P5-20100" PN="Chest X-Ray" S="2.16.840.1.113883.6.1"/> <patient_encounter> <encounter_tmr LOW="19991107"/> </patient_encounter> <patient> <patient.type_cd V="PAT"/> <person> <id V="123456789" AA="2.16.840.113.933"/> <person_name> <nm><G V="Henry"/> <F V="Levin"/> <SF V="the 7th"/></nm> <person_name.type_cd V="L"/> </person_name> </person> <birth_dttm V="19320513"/> <administrative_gender_cd V="M"/> </patient> </clinical_document_header> <body> … </body></levelone>

<RadiologyReport> <Header> <Name> Henry Levin, the 7th </Name> <MRN> 123456789</MRN> < SEX>Male</ SEX> < DOB>May 13, 1923</ DOB> <PROCEDURE> Chest X-Ray <ID code=" P5-20100" system=" SNOMED"/> <DATE> November 07, 1999 </DATE> </PROCEDURE> </Header> <Body> … </Body></RadiologyReport>

Locally applied markup CDA markup

Element Sequence

Note: CDA markup not currentper the membership ballot


11

Locally applied markup CDA markup

Element vs. Attribute<levelone> <clinical_document_header> <clinical_document_header.service_cd V="P5-20100" PN="Chest X-Ray" S="2.16.840.1.113883.6.1"/> <patient_encounter> <encounter_tmr LOW="19991107"/> </patient_encounter> <patient> <patient.type_cd V="PAT"/> <person> <id V="123456789" AA="2.16.840.113.933"/> <person_name> <nm><G V="Henry"/> <F V="Levin"/> <SF V="the 7th"/></nm> <person_name.type_cd V="L"/> </person_name> </person> <birth_dttm V="19320513"/> <administrative_gender_cd V="M"/> </patient> </clinical_document_header> <body> … </body></levelone>

<RadiologyReport> <Header> <Name> Henry Levin, the 7th </Name> <MRN> 123456789</MRN> <SEX>Male</SEX> <DOB> May 13, 1923</DOB> <PROCEDURE> Chest X-Ray <ID code=" P5-20100" system=" SNOMED"/> <DATE> November 07, 1999 </DATE> </PROCEDURE> </Header> <Body> … </Body></RadiologyReport>


12


Required Element<levelone> <clinical_document_header> <id V="N3" AA="2.16.840.1.1138.933"/> <clinical_document_header.service_cd V="P5-20100" PN="Chest X-Ray" S="2.16.840.1.113883.6.1"/> <patient_encounter> <encounter_tmr LOW="19991107"/> </patient_encounter> <patient> <patient.type_cd V="PAT"/> <person> <id V="123456789" AA="2.16.840.113.933"/> <person_name> <nm><G V="Henry"/> <F V="Levin"/> <SF V="the 7th"/></nm> <person_name.type_cd V="L"/> </person_name> </person> <birth_dttm V="19320513"/> <administrative_gender_cd V="M"/> </patient> </clinical_document_header> <body> … </body></levelone>

<RadiologyReport> <Header> <Name> Henry Levin, the 7th </Name> <MRN> 123456789</MRN> <SEX> Male</SEX> <DOB> May 13, 1923</DOB> <PROCEDURE> Chest X-Ray <ID code=" P5-20100" system=" SNOMED"/> <DATE> November 07, 1999 </DATE> </PROCEDURE> </Header> <Body> … </Body></RadiologyReport>

CDA markup


13


Vocabulary Domains<levelone> <clinical_document_header> <clinical_document_header.service_cd V="P5-20100" PN="Chest X-Ray" S="2.16.840.1.113883.6.1"/> <patient_encounter> <encounter_tmr LOW="19991107"/> </patient_encounter> <patient> <patient.type_cd V="PAT"/> <person> <id V="123456789" AA="2.16.840.113.933"/> <person_name> <nm><G V="Henry"/> <F V="Levin"/> <SF V="the 7th"/></nm> <person_name.type_cd V="L"/> </person_name> </person> <birth_dttm V="19320513"/> <administrative_gender_cd V="M"/> </patient> </clinical_document_header> <body> … </body></levelone>

<RadiologyReport> <Header> <Name> Henry Levin, the 7th </Name> <MRN> 123456789</MRN> < SEX>Male</ SEX> <DOB> May 13, 1923</DOB> <PROCEDURE> Chest X-Ray <ID code=" P5-20100" system=" SNOMED"/> <DATE> November 07, 1999 </DATE> </PROCEDURE> </Header> <Body> … </Body></RadiologyReport>

CDA markup


14


Different (lexical) Datatypes<levelone> <clinical_document_header> <clinical_document_header.service_cd V="P5-20100" PN="Chest X-Ray" S="2.16.840.1.113883.6.1"/> <patient_encounter> <encounter_tmr LOW="19991107"/> </patient_encounter> <patient> <patient.type_cd V="PAT"/> <person> <id V="123456789" AA="2.16.840.113.933"/> <person_name> <nm><G V="Henry"/> <F V="Levin"/> <SF V="the 7th"/></nm> <person_name.type_cd V="L"/> </person_name> </person> <birth_dttm V="19320513"/> <administrative_gender_cd V="M"/> </patient> </clinical_document_header> <body> … </body></levelone>

<RadiologyReport> <Header> <Name> Henry Levin, the 7th </Name> <MRN> 123456789</MRN> <SEX> Male</SEX> < DOB>May 13, 1923</ DOB> <PROCEDURE> Chest X-Ray <ID code=" P5-20100" system=" SNOMED"/> <DATE> November 07, 1999 </DATE> </PROCEDURE> </Header> <Body> … </Body></RadiologyReport>

CDA markup


15


Different Definitions<levelone> <clinical_document_header> <clinical_document_header.service_cd V="P5-20100" PN="Chest X-Ray" S="2.16.840.1.113883.6.1"/> <patient_encounter> <encounter_tmr LOW="19991107"/> </patient_encounter> <patient> <patient.type_cd V="PAT"/> <person> <id V="123456789" AA="2.16.840.113.933"/> <person_name> <nm><G V="Henry"/> <F V="Levin"/> <SF V="the 7th"/></nm> <person_name.type_cd V="L"/> </person_name> </person> <birth_dttm V="19320513"/> <administrative_gender_cd V="M"/> </patient> </clinical_document_header> <body> … </body></levelone>

<RadiologyReport> <Header> <Name> Henry Levin, the 7th </Name> <MRN> 123456789</MRN> <SEX> Male</SEX> <DOB> May 13, 1923</DOB> <PROCEDURE>Chest X-Ray <ID code=" P5-20100" system=" SNOMED"/> <DATE> November 07, 1999 </DATE> </PROCEDURE> </Header> <Body> … </Body></RadiologyReport>

CDA markup


16

XSLT

• stylesheet is a sequence of templates– template can be thought of as rules

• each template has 2 parts– match pattern

• determines which element/attribute/etc. nodes thetemplate applies to

– template body• a combination of explicit markup and XSLT

commands

• determines the transformation that will beperformed on the nodes matched by pattern


17

XSLT: Processing Model

• Set the current node to the documentnode

• find patterns that match– choose the "best" pattern

– apply the template• typically selects one or more additional nodes to

process

– appending result to the output tree

• Recurse until no new nodes are selected


18

Match an element name

<xsl:template match="section">{action}

</xsl:template>

XPath: Simple Patterns


19

<xsl:template match="body|caption|content">{action}

</xsl:template>


Match any one of many elementnames


20


Match an attribute name

<xsl:template match="@ignore">{action}

</xsl:template>


21

XPath: Complex Patterns

Match a "path"

<xsl:template match="section/section/paragraph">{action}

</xsl:template>


22

XPath: Complex Patterns

Match a predicate

<xsl:template match="observation_media.value [@MD=’image/gif’ or @MD=’image/jpeg]">

{action}</xsl:template>


23

XPath: Misc PatternsMatch the context node

<xsl:template match=".">{action}

</xsl:template>

Match the parent node

<xsl:template match="..">{action}

</xsl:template>


24

XPath: Misc PatternsMatch any element

<xsl:template match="*">{action}

</xsl:template>

Match any attribute

<xsl:template match="@*">{action}

</xsl:template>


25

XPath: Misc Patterns

Match a node type

<xsl:template match="text()">{action}

</xsl:template>

<xsl:template match="comment()">{action}

</xsl:template>


26

XSLT: Built-In Templates

<xsl:template match="*|/"><xsl:apply-templates/>

</xsl:template>

<xsl:template match="text()|@*"><xsl:value-of select="."/>

</xsl:template>

<xsl:template match="processing-instruction()|comment()"/></xsl:template>


27

XSLT: Commands (Actions)

<xsl:apply-templates/>

<xsl:apply-templates select=’pattern’/>

apply-templates


28


Conditionals: if

<xsl:if test=’predicate’>{action}

</xsl:if>


29

XSLT: Commands (Actions)Conditionals: choose (if/then/else)

<xsl:choose><xsl:when test=’predicate’>

{action}<xsl:/when><xsl:when test=’predicate’>

{action}</xsl:when><xsl:otherwise>

{action}</xsl:otherwise>

</xsl:choose>


30


Repetition: for-each

<xsl:for-each select=’pattern’>{action}

</xsl:for-each>


31


Sorting

<xsl:for-each select=’pattern’><xsl:sort order=’ascending|descending’/>

</xsl:for-each>


32


Getting an element’s content or anattribute’s value

<xsl:value-of select=’pattern’/>


33


<xsl:variable name=’name’ select=’pattern’/>

<xsl:value-of select=’$name’/>

Setting a variable

Getting a variable’s value

<xsl:apply-templates select=’pattern-with-$variable’/>


34

<levelone> <clinical_document_header> <clinical_document_header.service_cd V="P5-20100" PN="Chest X-Ray" S="2.16.840.1.113883.6.1"/> <patient_encounter> <encounter_tmr LOW="19991107"/> </patient_encounter> <patient> <patient.type_cd V="PAT"/> <person> <id V="123456789" AA="2.16.840.113.933"/> <person_name> <nm><G V="Henry"/> <F V="Levin"/> <SF V="the 7th"/></nm> <person_name.type_cd V="L"/> </person_name> </person> <birth_dttm V="19320513"/> <administrative_gender_cd V="M"/> </patient> </clinical_document_header> <body> … </body></levelone>

<RadiologyReport> <Header> <Name> Henry Levin, the 7th </Name> <MRN> 123456789</MRN> < SEX>Male</ SEX> < DOB>May 13, 1923</ DOB> <PROCEDURE> Chest X-Ray <ID code=" P5-20100" system=" SNOMED"/> <DATE> November 07, 1999 </DATE> </PROCEDURE> </Header> <Body> … </Body></RadiologyReport>


Element SequenceCDA markup


35

<xsl:template match=’Header’> ... <xsl:apply-templates select=’DOB’/> <xsl:apply-templates select=’SEX’/> ...</xsl:template>

Element Sequence


36


Element vs. Attribute<levelone> <clinical_document_header> <clinical_document_header.service_cd V="P5-20100" PN="Chest X-Ray" S="2.16.840.1.113883.6.1"/> <patient_encounter> <encounter_tmr LOW="19991107"/> </patient_encounter> <patient> <patient.type_cd V="PAT"/> <person> <id V="123456789" AA="2.16.840.113.933"/> <person_name> <nm><G V="Henry"/> <F V="Levin"/> <SF V="the 7th"/></nm> <person_name.type_cd V="L"/> </person_name> </person> <birth_dttm V="19320513"/> <administrative_gender_cd V="M"/> </patient> </clinical_document_header> <body> … </body></levelone>

<RadiologyReport> <Header> <Name> Henry Levin, the 7th </Name> <MRN> 123456789</MRN> <SEX>Male</SEX> <DOB> May 13, 1923</DOB> <PROCEDURE> Chest X-Ray <ID code=" P5-20100" system=" SNOMED"/> <DATE> November 07, 1999 </DATE> </PROCEDURE> </Header> <Body> … </Body></RadiologyReport>


37

<xsl:template match=’SEX’> <administrative_gender_cd> <xsl:attribute name=’V’> <xsl:choose> <xsl:when test=’text()="Male"’>M</xsl:when> <xsl:when test=’text()="Female"’>F</xsl:when> </xsl:choose> </xsl:attribute> </administrative_gender_cd></xsl:template>

Element vs. Attribute


38


Required Element<levelone> <clinical_document_header> <id V="a123" AA="2.16.840.1.1138.933"/> <clinical_document_header.service_cd V="P5-20100" PN="Chest X-Ray" S="2.16.840.1.113883.6.1"/> <patient_encounter> <encounter_tmr LOW="19991107"/> </patient_encounter> <patient> <patient.type_cd V="PAT"/> <person> <id V="123456789" AA="2.16.840.113.933"/> <person_name> <nm><G V="Henry"/> <F V="Levin"/> <SF V="the 7th"/></nm> <person_name.type_cd V="L"/> </person_name> </person> <birth_dttm V="19320513"/> <administrative_gender_cd V="M"/> </patient> </clinical_document_header> <body> … </body></levelone>

<RadiologyReport> <Header> <Name> Henry Levin, the 7th </Name> <MRN> 123456789</MRN> <SEX> Male</SEX> <DOB> May 13, 1923</DOB> <PROCEDURE> Chest X-Ray <ID code=" P5-20100" system=" SNOMED"/> <DATE> November 07, 1999 </DATE> </PROCEDURE> </Header> <Body> … </Body></RadiologyReport>

CDA markup


39

<xsl:template match=’Header’> ... <id AA=’2.16.840.1.1138.933’> <xsl:attribute name=’V’>

<xsl:value-of select=’generate-id()’/> </xsl:attribute> </id> ...</xsl:template>

Required Element


40


Vocabulary Domains<levelone> <clinical_document_header> <clinical_document_header.service_cd V="P5-20100" PN="Chest X-Ray" S="2.16.840.1.113883.6.1"/> <patient_encounter> <encounter_tmr LOW="19991107"/> </patient_encounter> <patient> <patient.type_cd V="PAT"/> <person> <id V="123456789" AA="2.16.840.113.933"/> <person_name> <nm><G V="Henry"/> <F V="Levin"/> <SF V="the 7th"/></nm> <person_name.type_cd V="L"/> </person_name> </person> <birth_dttm V="19320513"/> <administrative_gender_cd V="M"/> </patient> </clinical_document_header> <body> … </body></levelone>

<RadiologyReport> <Header> <Name> Henry Levin, the 7th </Name> <MRN> 123456789</MRN> < SEX>Male</ SEX> <DOB> May 13, 1923</DOB> <PROCEDURE> Chest X-Ray <ID code=" P5-20100" system=" SNOMED"/> <DATE> November 07, 1999 </DATE> </PROCEDURE> </Header> <Body> … </Body></RadiologyReport>

CDA markup


41

<xsl:template match=’SEX’> <administrative_gender_cd> <xsl:attribute name=’V’> <xsl:choose> <xsl:when test=’text()="Male"’>M</xsl:when> <xsl:when test=’text()="Female"’>F</xsl:when> </xsl:choose> </xsl:attribute> </administrative_gender_cd></xsl:template>

Vocabulary Domains


42


Different (lexical) Datatypes<levelone> <clinical_document_header> <clinical_document_header.service_cd V="P5-20100" PN="Chest X-Ray" S="2.16.840.1.113883.6.1"/> <patient_encounter> <encounter_tmr LOW="19991107"/> </patient_encounter> <patient> <patient.type_cd V="PAT"/> <person> <id V="123456789" AA="2.16.840.113.933"/> <person_name> <nm><G V="Henry"/> <F V="Levin"/> <SF V="the 7th"/></nm> <person_name.type_cd V="L"/> </person_name> </person> <birth_dttm V="19320513"/> <administrative_gender_cd V="M"/> </patient> </clinical_document_header> <body> … </body></levelone>

<RadiologyReport> <Header> <Name> Henry Levin, the 7th </Name> <MRN> 123456789</MRN> <SEX> Male</SEX> < DOB>May 13, 1923</ DOB> <PROCEDURE> Chest X-Ray <ID code=" P5-20100" system=" SNOMED"/> <DATE> November 07, 1999 </DATE> </PROCEDURE> </Header> <Body> … </Body></RadiologyReport>

CDA markup


43

Different (lexical) Datatypes

<xsl:template match=’DOB’> <birth_dttm> <xsl:attribute name=’V’> <xsl:call-template name=’format-date’> <xsl:with-param name=’date’> <xsl:value-of select=’text()’/> </xsl:with-param> </xsl:call-template> </xsl:attribute> </birth_dttm></xsl:template>


44


Different Definitions<levelone> <clinical_document_header> <clinical_document_header.service_cd V="P5-20100" PN="Chest X-Ray" S="2.16.840.1.113883.6.1"/> <patient_encounter> <encounter_tmr LOW="19991107"/> </patient_encounter> <patient> <patient.type_cd V="PAT"/> <person> <id V="123456789" AA="2.16.840.113.933"/> <person_name> <nm><G V="Henry"/> <F V="Levin"/> <SF V="the 7th"/></nm> <person_name.type_cd V="L"/> </person_name> </person> <birth_dttm V="19320513"/> <administrative_gender_cd V="M"/> </patient> </clinical_document_header> <body> … </body></levelone>

<RadiologyReport> <Header> <Name> Henry Levin, the 7th </Name> <MRN> 123456789</MRN> <SEX> Male</SEX> <DOB> May 13, 1923</DOB> <PROCEDURE>Chest X-Ray <ID code=" P5-20100" system=" SNOMED"/> <DATE> November 07, 1999 </DATE> </PROCEDURE> </Header> <Body> … </Body></RadiologyReport>

CDA markup


45

Different Definitions<xsl:template match=’PROCEDURE’> <clinical_document_header.service_cd> <xsl:attribute name=’V’> <xsl:value-of select=’ID/@code’/> </xsl:attribute> <xsl:attribute name=’PN’> <xsl:value-of select=’text()’/> </xsl:attribute> <xsl:attribute name=’S’> <xsl:call-template name=’map-code-system’> <xsl:with-param name=’system’ select=’ID/@system’/> </xsl:call-template> </xsl:attribute> </clinical_document_header.service_cd></xsl:template>

Document Object Model


47

What is the DOM?

• Document Object Model (DOM)– Tree-based API

• Represents a parsed document as tree of typednodes

– element, attribute, characterData, etc.

• Processing consists of traversing the tree andperforming operations on the nodes

• W3C Recommendation– Current version: Level 1

• Level 2 in "candidate recommendation" stage now


48

<?xml version="1.0"?><hello level="0">

<world>goodbye</world><hello level="1">

<world>goodbye</world></hello>

</hello>

Tree-based APIs

Level=0Level=0hellohello

worldworld hellohello

worldworld

Level=1Level=1

goodbyegoodbye

goodbyegoodbye

elementselements

attrsattrs

charDatacharData


49

Hello World, DOM-styleimport org.w3c.dom.* ; import org.xml.sax.* ;import com.ibm.xml.parsers.DOMParser ; import java.io.* ;public class HelloWorld{

public static void main (String[] args){

Document domTree = createDOMTree (args[0]) ;traverseDOMTree (domTree.getDocumentElement (), 0) ;

}static void traverseDOMTree (Node node, int indent){

for (int i = 0 ; i < indent ; i++) {System.out.print ("\t") ;}

System.out.println(node.getNodeName() + ":" + node.getNodeValue()) ;

if (node.hasChildNodes ()) {NodeList nl = node.getChildNodes () ;for (int i = 0 ; i < nl.getLength () ; i++) {

traverseDOMTree (nl.item (i), indent + 1) ;}

}}static Document createDOMTree (String xmlFile) {…}

}


50

Hello World, DOM-Style

c:\>type helloworld.xml<?xml version="1.0"?><hello>


c:\>java HelloWorld helloworld.xmlhello:null

#text:\n\tworld:null

#text:goodbye#text:\n


51

Node Types

• Document

• Element

• Attr

• Comment

• Text

• CDATASection

• DocumentType

• EntityReference

• Entity

• DocumentFragment

• Notation

• ProcessingInstruction


52

DOM: Fundamental Interfaces

• Attr

• CharacterData

• Document

• Element

• Node

• Text

• NodeList


53

MethodsMethodsNode Interface

• getAttributes

• getChildNodes

• getFirstChild

• getLastChild

• getNextSibling

• getOwnerDocument

• getNodeName

• getNodeType

• getNodeValue

• getParentNode

• getPreviousSibling

• hasChildNodes

• appendChild

• cloneNode

• insertBefore

• removeChild

• replaceChild

• setNodeValue


54

MethodsMethods

Element Interface

• getAttributeNode

• setAttributeNode

• removeAttributeNode

• normalize

• getTagName

• getAttribute

• setAttribute

• removeAttribute

• getElementsByTagName


55

MethodsMethods

Attr Interface

• getValue

• setValue

• getName

• getSpecified


56

Get an attribute

import org.w3c.dom.* ; import org.xml.sax.* ;import com.ibm.xml.parsers.DOMParser ; import java.io.* ;public class HelloWorld{

public static void main (String[] args){

Document domTree = createDOMTree (args[0]) ;String sex = getPatientSex (domTree.getDocumentElement ()) ;

System.out.println ("sex is " + sex) ;}public static String getPatientSex (Document doc){

NodeList nl = doc.getElementsByTagName("administrative_gender_cd") ;

Element sex = (Element) nl.item (0) ;Attr value = sex.getAttributeNode ("V") ;

return (value.getValue ()) ;}static Document createDOMTree (String xmlFile) {…}

}

Simple API for XML (SAX)


58

What is SAX?

• Simple API for XML (SAX)– Event-based API

• Represent a parsed document as a sequence ofparse events

– startElement, characterData, endElement, etc.

• Processing consists of dispatching events from anevent queue or handling callbacks registered foreach event

• NOT a W3C Recommendation– a "de-facto" standard

– originally designed by David Megginson

– design continues on XML-DEV mailing list


59

Hello World, SAX-Style

import org.xml.sax.* ; import org.xml.sax.helpers.* ;import java.io.* ;public class HelloWorldSAXHelper extends HandlerBase{// this helper class should be instantiated by a static main() somewhere// the following methods implement the SAX DocumentHandler interface

public void startElement (String name, AttributeList atts){

System.out.println ("startElement: " + name) ;}public void characters (char c[], int x, int y){

System.out.println ("characters: " + new String (c, x, y)) ;}public void endElement (String name){

System.out.println ("endElement: " + name) ;}public void ignorableWhitespace (char c[], int x, int y){

System.out.println("ignorableWhitespace: "+ new String(c, x, y));}

}


60

Hello World, SAX-Stylec:\>type helloworld.xml<?xml version="1.0"?><hello>


c:\>java HelloWorldSAX helloworld.xmlstartElement: helloignorableWhitespace:\n\tstartElement: worldcharacters: goodbyeendElement: worldignorableWhitespace:\nendElement: hello


61

Application WritersApplication Writers Parser WritersParser Writers

Interfaces

• DocumentHandler

• ErrorHandler

• DTDHandler

• EntityResolver

• Parser

• AttributeList

• Locator


62

MethodsMethods

DocumentHandler Interface

• startDocument

• startElement

• characters

• endElement

• endDocument

• ignorableWhitespace

• setDocumentLocator

• processingInstruction


63

MethodsMethods

Parser Interface

• parse

• setDocumentHandler

• setDTDHandler

• setEntityResolver

• setErrorHandler

• setLocale


64

MethodsMethods

AttributeList Interface

• getLength

• getName

• getType

• getValue


65

Outro

• Extensible Stylesheet Language (XSL)– XSL Transformation Language (XSLT)

– XML Path Language (XPath)

• Document Object Model (DOM)

• Simple API for XML (SAX)

• Namespaces in XML [optional]

Namespaces in XML


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Namespaces in XML

• An XML namespace is a collection ofnames, identified by a URI reference,which are used in XML documents aselement types and attribute names

• Names from XML namespaces appear asqualified names, which contain a singlecolon, separating the name into anamespace prefix and a local part

• The prefix, which is mapped to a URIreference, selects a namespace.


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Namespace Declarations

<!ELEMENT NAME (First, Middle?, Last, Suffix?)><!ELEMENT Name xmlns CDATA #IMPLIED>

<RadiologyReport> <PatientInfo> <Name xmlns="http://www.radiology.org/report"> <First>Amy</First> <Middle>A.</Middle> <Last>Fall</Last> </Name> … </PatientInfo> ….</RadiologyReport>

XML Document

Default NamespaceThe namespace name in the attribute value is that of the default namespace inthe scope of the element to which the declaration is attached. In such a defaultdeclaration, the attribute value may be empty.


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Namespace Declarations

<!ELEMENT NAME (First, Middle?, Last, Suffix?)><!ELEMENT Name xmlns:radorg CDATA #IMPLIED>

<RadiologyReport> <PatientInfo> <Name xmlns:radorg="http://www.radiology.org/report"> <First>Amy</First> <Middle>A.</Middle> <Last>Fall</Last> </Name> … </PatientInfo> ….</RadiologyReport>

XML Document

Namespace PrefixThe local part gives the namespace prefix, used to associate element andattribute names with the namespace name in the attribute value in the scope ofthe element to which the declaration is attached.


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Qualified NamesStart tag Content End tag

<<radorgradorg:Name> :Name> Female </</radorgradorg:Name>:Name>

Namespace qualified element name

Start tag Attribute Content End tag

<patient.sex hl7:table=<patient.sex hl7:table=“HL70001“HL70001”>> Female</ patient.sex></ patient.sex>

Namespace qualified attribute


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Qualified Names

<!ELEMENT NAME (First, Middle?, Last, Suffix?)><!ELEMENT Name xmlns:radorg CDATA #IMPLIED>

<RadiologyReport> <PatientInfo> <radorg:Name xmlns:radorg="http://www.radiology.org/report"> <First>Amy</First> <Middle>A.</Middle> <Last>Fall</Last> </radorg:Name> … </PatientInfo> ….</RadiologyReport>

XML Document

Namespace PrefixThe local part gives the namespace prefix, used to associate element andattribute names with the namespace name in the attribute value in the scope ofthe element to which the declaration is attached.


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References• XSL

– W3C. Extensible Stylesheet Language (XSL).W3C Working Draft.

– http://www.w3.org/TR/WD-xsl

• XPath– W3C. XML Path Language. W3C

Recommendation.– http://www.w3.org/TR/xpath

• XSLT– W3C. XSL Transformations (XSLT). W3C

Recommendation.– http://www.w3.org/TR/xslt


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References• DOM

– W3C. Document Object Model (DOM)Level 1 Specification. W3C Recommendation.

– http://www.w3.org/TR/REC-DOM-Level-1

• SAX– XML-DEV. Simple API for XML (SAX). De-

facto Standard.– http://www.megginson.com/SAX

• XML Names– W3C. Namespaces in XML. W3C

Recommendation.– http://www.w3.org/TR/REC-xml-names