• Namespace information are represented as namespace node which maps in scope on an element

• Attach to every element node where namespace is declared

root

comment element

namespace text element

namespace text element

//title[@lang="de"]

/descendant-or-self::book[last()]

//node() or //*

//book[price>30]

<?xml version="1.0" encoding="ISO-8859-1"?><bookstore>

<book category="COOKING"><title lang="de">Everyday Italian</title><author>Giada De Laurentiis</author><year>2005</year><price>30.00</price>

</book><book category="CHILDREN">

<title lang="en">Harry Potter</title><author>J K. Rowling</author><year>2005</year><price>29.99</price>

</book><book category="WEB">

<title lang="en">XQuery Kick Start</title><author>James McGovern</author><author>Per Bothner</author><author>Kurt Cagle</author><author>James Linn</author><author>Vaidyanathan Nagarajan</author><year>2003</year><price>49.99</price>

</book><book category="WEB">

<title lang="en">Learning XML</title><author>Erik T. Ray</author><year>2003</year><price>39.95</price>

</book></bookstore>

//author[../title[contains(string(.),"XML")]]

//title[contains(string(.),"XML")]/parent::node()/child::author

for $x in //book return if(contains(string($x/title),"XML"))then (replace($x/title, "XML", "Extensible Markup Language"))elseupper-case($x/title)

for $x in //book returnif( $x/price >= 35.00)then (replace( string($x/price), string($x/price), 40 cast as xs:string))else$x/price

XPath variable are “read-only” and cannot be modified

for $x in //booklet $y:=$x/pricereturn if( $y >= 35.00)then ($y=40.00)else$x/price

<?xml version="1.0" encoding="UTF-8"?><class name="input">

<description>This class handles input</description><function name="text">

<argument type="string"/><return type="int"/>

</function><function name="number">

<argument type="string"/></function>

</class>

Expression Result

count( //* ) 7

count( //@* ) 6

count( //argument ) 2

count( //class ) 1

count( //function ) 2

count( //description ) 1

count( //return ) 1

count( //text() ) 1

count( //function/return ) 1

count( //function/argument )

2

count( //class/* ) 3

count( //description/* ) 0

//class/description {"This class handles input"}

//@name {"input", "text", "number"}

//@type {"string", "int", "string"}

//return/@type {"int"}

//argument/@type {"string", "string"}

boolean( //function/@name )

true

boolean( //class/@name ) true