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Transforming XML Part I Document Navigation with XPath John Arnett, MSc Standards Modeller Information and Statistics Division NHSScotland Tel: 0131 551.

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Presentation on theme: "Transforming XML Part I Document Navigation with XPath John Arnett, MSc Standards Modeller Information and Statistics Division NHSScotland Tel: 0131 551."— Presentation transcript:

1 Transforming XML Part I Document Navigation with XPath John Arnett, MSc Standards Modeller Information and Statistics Division NHSScotland Tel: (x2073)

2 Contents Document Processing Nodes and Trees XPath: Locating Nodes Summary Find Out More

3 Document Processing The XSL Family –XPath (XML Path Language) –XSLT (Extensible Stylesheet Language Transformations) –XSL aka XSL-FO (Extensible Stylesheet Language Formatting Objects)

4 Document Processing XPath –Used to locate specific parts of an XML source document efficiently and effectively –XPath v1.0 W3C Recommendation

5 Document Processing XSLT –Used to transform XML documents to another XML or non-XML form – esp. HTML –XSLT v1.0 W3C Recommendation v2.0 W3C Working Draft –Uses XPath for locating document content

6 Document Processing XSL(-FO) –Used to format XML documents into fixed sized folios for publication –XSL v1.0 W3C Recommendation –Uses XSLT for document transformation

7 Document Processing Transformation and formatting –XPath used to locate nodes for input –XSLT used to transform input and generate result tree –XSL-FO used to format output document

8 Document Processing Adapted from XSLT Basics slide presentation by Paul Spencer, alphaXML Source Tree Style sheet FormatTransform Result Tree Formatted Output Stylesheet Processor

9 Trees and Nodes XML document is viewed as a source tree containing different node types –root –element –text –attribute –namespace –processing instruction –comment

10 Trees and Nodes XML Appointment example John Smith Alison Young 14:30:00

11 Trees and Nodes XPath view of Appointment source tree

12 XPath: Locating Nodes XPath expressions (location paths) –Used to navigate source tree and locate nodes for input –Comprised of one or more location steps axis + node test + (optional) predicate –May contain functions, e.g. position(), count(node-set), last()

13 XPath: Locating Nodes Axes –Specify node locations relative to the current (context) node = self –May traverse tree forwards or backwards

14 XPath: Locating Nodes Axes for forward traversal –child –attribute –descendant-or-self –descendant –following –following-sibling –namespace

15 XPath: Locating Nodes Axes for reverse traversal –parent –ancestor –ancestor-or-self –preceding –preceding-sibling

16 XPath: Locating Nodes Node Tests –Refine node set selection * = select all nodes of same type node() = select all nodes of any type Select all nodes of type text(), comment() or processing- instruction() Select all nodes with specified name

17 XPath: Locating Nodes Select Clinician element node child::Appointment/child::Clinician or Appointment/Clinician

18 XPath: Locating Nodes Select upi attribute node child::Patient/attribute::upi or

19 XPath: Locating Nodes Select all descendant text nodes /descendant-or-self::node()/child::text() or //text()

20 XPath: Locating Nodes Select parent of StartTime element parent::node() or..

21 XPath: Locating Nodes Using wildcards child::* or *

22 XPath: Locating Nodes Abbreviating location steps –child:: and text() can usually be omitted child::Appointment/child::Clinician/child ::text() = Appointment/Clinician –attribute:: –self()::node =. –parent::node() =..

23 XPath: Locating Nodes Abbreviating Location Paths /descendant-or-self::node()/ = // /descendant-or-self::node()/child::text() = //text()

24 In Summary… XML document processing: –XPath - node location –XSLT - transformation –XSL-(FO) - document formatting XPath used to navigate source tree Transformation performed by applying style sheet to source document

25 Find Out More The Extensible Stylesheet Language Family (XSL) –www.w3.org/Style/XSL/www.w3.org/Style/XSL/ W3C XML Path Language v1.0 Specification –www.w3.org/TR/xpathwww.w3.org/TR/xpath TopXML XSLT & XPath Tutorial –www.vbxml.com/xsl/tutorials/intro/d efault.aspwww.vbxml.com/xsl/tutorials/intro/d efault.asp


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