1. More XML XML schema, XPATH, XSLT
CS 431 –
Carl Lagoze – Cornell University

2. Distributed, interlinked
A little context
RDF
Semantic
Relationships
DAML+OIL
Concept
Building
Semantic Web
Traditional Library
Central control
Uniform expertise
Traditional Web
Distributed, interlinked
Viewable Documents
Xpath
Data
Decomposition
XSLT
Transformation
Schema
Type Definition
Namespaces
Concept
Integration
DTD
Tag Sets
XML
Markup Syntax
URIs
Name Convention
HTTP
Access Method

3. Language for addressing parts of an XML document
XPath
Language for addressing parts of an XML document
XSLT
Xpointer
Tree model similar to DOM
W3C Recommendation (1999)

4. Location Steps – selection from context node
Xpath Concepts
Context Node
current node in XML document that is basis of path evaluation
Default to root
Location Steps – selection from context node
Axis – sub-tree(s) selection from context node
Node Test – select specific elements or node type(s)
Predicates – predicate for filtering after axis and node tests

5. Axis
child: all children of context
descendent: all children, grandchildren, …
parent:
ancestor

6. Node Test
Element name: e.g. “Book”
Wildcard: *
Type(): where type is “node”, “text”, etc.

7. Boolean and comparative operators Types
Predicate
Boolean and comparative operators
Types
Numbers
Strings
node-sets
Functions
Examples
boolean starts-with(string, string)
number count(node-set)

8. Combining all into a location set specification
Syntax: axis::node-test[predicate]
Examples:
child::Book[position() <= 3] – first three <Book> child elements of context
child::Book/attribute::color – “color” attributes of <Book> child elements of context

9. “.” (self), “..” (parent), “//” (descendent-or-self)
Abbreviations
Child axis is default
child::Book  Book
Attribute axis
Book[position() =
“.” (self), “..” (parent), “//” (descendent-or-self)
position() = n  n
Example

10. XML Transformations (XSLT)
Origins: separate rendering from data
Roots in CSS
W3C Recommendation
Generalized notion of transformation for:
Multiple renderings
Structural transformation between different languages
Dynamic documents
XSLT – rule-based (declarative) language for transformations

11. XSLT Capabilities
Generate constant text
Filter out content
Change tree ordering
Duplicate nodes
Sort nodes
Any computational task (XSLT is “turing complete”)

12. Output doc (xml, html, etc)
XSLT Processing Model
parse
XSLT
serialize
Input XML doc
Parsed tree
Xformed tree
Output doc (xml, html, etc)

13. XSLT “engine” XSLT Engine (SAXON) XML input Output Document
(xml, html, …)
XSLT
“program”

14. Stylesheet Document or Program
XML document rooted in <stylesheet> element
Body is set of templates
Xpath expression specifies elements in source tree
Body of template specifies contribution of source elements to result tree
Not sequential execution

15. Template Form Elements from xsl namespace are transform instructions
Match attribute value is xpath expression
Non-xsl namespace elements are literals.

16. A simple example XSLT file XML base file
XML base file

17. XSLT Recursive Programming Style
Document driven, template matching
Conflict resolution rules
Mode setting
<xsl:apply-templates mode=“this”>
<xsl:template match=“foo” mode=“this”>
<xsl:template match=“foo” mode=“that”>
Context setting
<xsl:apply-templates select=“//bar”>

18. XSLT Procedural Programming
Sequential programming style
Basics
for-each – loop through a set of elements
call-template – like a standard procedure call

19. For-each programming example
XSLT file
XML base file

20. Call-template programming example
XML base file
XSLT file

21. Result Tree Creation
Literals – any element not in xsl namespace
<xsl:text> - content directly to output
<xsl:value-of> - expression processing
<xsl:copy> and <xsl:copyof> - Copy current node or selected nodes into result tree
<xsl:element> - instantiate an element
<xsl:attribute> - instantiate an attribute

22. Various other programming constructs
Conditionals
Variables (declaration and use)
Some type conversion
Sorting

23. Resources XSLT – WROX Press W3C XSLT Page TopXML XSL Tutorial
ISBN
W3C XSLT Page
TopXML XSL Tutorial

24. XML Schema Define…
elements
attributes
Nesting structure (parent/child rela.)
Sibling sequence
Sibling cardinality
Presence or absence of text values
Element and attribute data types
Element and attribute default values

25. Simple vs. Complex Values
Element with complex value contains other elements (has children)
Element with simple value does not have children (e.g. text).

26. Restriction on type of content Syntax
Simple Value Types
Restriction on type of content
Syntax
<xs:element name=“xxx” type=“yyy”/>
Examples
<xs:element name=“lastname” type=“xs:string”/>
<xs:element name=“age” type=“xs:number”/>
<xs:element name=“age” type=“xs:date”/>

27. Facets
Restrictions on values within type context
Examples

28. Memo Instance Document
Simple Example
Memo Schema
Memo Instance Document

29. Type extension/restriction

30. Type Reuse

31. Type Reuse Example Base Type Definition Type Use Instance Document
Type Use
Instance Document

32. DTD & XML Schema Equivalence
DTD Example
Equivalent Schema
Instance Document