The document discusses XML and related technologies: 1. XML is used to mark up data with user-defined tags and describes the structure of data. It is more flexible than HTML which uses predefined tags. 2. XML documents must follow basic rules like being well-formed with matching tags and properly nested elements. 3. XML can be validated using DTDs or XML Schema which define constraints and data types for elements.

1. XML
Farag Zakaria
ITI-JAVA 30
FCI-CU 2007
Farag_cs2005@yahoo.com

2. Agenda
 Introduction
 XML vs. HTML
 XML basic rules
 XML overall structure & building blocks
 XML document validation
 XML related technologies.
 XML parsing (JAXP)
 JAXB

3. Introduction
 XML stands for eXtensible Markup Language.
 XML document describes the structure of data.
 XML has no mechanism to specify the format for
presenting data to the user.(you specify your
own tags and structure).
 XML document resides in its own file with an
“.xml” extension.
 XML derived from SGML(Standard Generalized
Markup Language).

4. XML vs. HTML
HTML
XML
Used to mark up data Mark up text (displayed to users)
(processed by computer)
Describes content(meaning) Describes both
only structure(<p>,<h2>, …) and
appearance(<br>,<font>,…)
Define your own tags Uses fixed, unchangeable set of
tags
Well formed Not

5. XML basic rules
 XML is case sensitive
 All start tags must have end tags.
 Elements must be properly nested.
 XML declaration is the first statement.
 Every document must contain a root element.
 Attribute values must have quotation marks.
<?xml version=“1.0”?>
 Certain characters are reserved for parsing ( as
<,>,&,’,”)
 Documents that follow these basic rules are well-
formed xml documents

6. XML overall structure & building
blocks
 Document may start with one or more processing
instructions(PI) or directives
- <?xml version=“1.0”?>
- PI provides application-specific document
information
 After PI there must be one root element containing all
rest xml.
 XML building blocks
1. Element <book name="Core JAVA"></book>
2. Tags <book name="Core JAVA"> </book>
3. Attributes <book name="Core JAVA"></book>
4. Entities (special characters)
<today>Sunny &amp; hot</today>
5. Character data
<today>Sunny &amp; hot</today>
6. Empty element has no body <book name=“Core JAVA”
/>

7. XML document
<?xml version="1.0" encoding="UTF-8"?> PI
<library> Root Element
<book name="Core JAVA"> Element
<author>Cornel</author> Sub Element
<chapters>12</chapters>
<price>40$</price>
</book>
<book name="Core JSF"> Element
<author>Cornel</author>
<chapters>8</chapters>
<price>35$</price>
</book>
</library>

8. XML document tree

9. XML document validation
 DTD (Document Type Definition)
- Defines the structure constraints for XML
documents.
- Documents that conform to DTD are Valid
documents.
 XML Schema
- Same as DTD, more powerful because it
includes facilities
to specify the data type of elements and it is
based on
XML.
- Documents that conform to Schema are
Schema valid

10. XML document validation(DTD)
 Can be categorized as
1. Internal subsets
Elements declarations inside the document.
<!DOCTYPE --DTD-Instructions-- >
2. External subsets
Elements declarations are outside the
document in file
with .dtd extension
<!DOCTYPE allbooks SYSTEM "book.dtd" >
3. External subsets in Internet
<!DOCTYPE allbooks public “URL/book.dtd" >

11. XML document validation(DTD)
(cont.)
 DTD file
<!ELEMENT book ( name , author ) >
<!ELEMENT name ( #PCDATA )>
<!ELEMENT author ( #PCDATA )>
<!ATTLIST book sellto CDATA #REQUIRED>
 XML file
<!DOCTYPE allbooks SYSTEM "book.dtd" >
<allbooks>
<book sellto=“Egypt”>
<name>Core JAVA</name>
<author>Cornell</author>
</book>
</allbooks>

12. DTD limitations
 Not written in XML syntax, DTD has its own
syntax. So it is hard to learn.
 Certain number of element repetitions can’t be
achieved.
 XML document can reference only 1 DTD.
 Do not support namespaces.
 No constraints on character data.
- PCDATA, CDATA allows any permutations of
characters.
- But if we need to limit element value to int 
Not in DTD
<chapters>8</chapters>  required

13. XML doc. validation(XML
Schema)
 Provide more powerful and flexible schema
language than DTD.
 It has 44 enhanced data types.
 You can create your own data types (Complex
Data types).
 Written in xml.

14. XML Schema Data types
 Simple type
1. Don’t have sub-element.
2. Don’t have attribute
Ex. <element name="price" type="integer" />
 Complex type(your own data type)
either have one of the following or all of them.
1. sub-element.
2. attributes.

15. Example (Schema)
<complexType name="book">
<sequence>
<element name="name" type="string" />
<element name="chapters" type="integer" />
<element name="price" type="integer" />
</sequence>
<attribute name="shipto" type="string" use="required"/>
</complexType>
<complexType name="library">
<sequence>
<element name="book" type="tns:book" minOccurs="1"
maxOccurs="2"/>
</sequence>
</complexType>
<element name="library" type="tns:library"></element>

16. Example(XML Document)
<tns:library
xmlns:tns="http://www.example.org/bookschema"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-
instance"
xsi:schemaLocation="bookschema.xsd ">
<tns:book shipto="Egypt">
<tns:name>Core Java</tns:name>
<tns:chapters>12</tns:chapters>
<tns:price>35</tns:price>
</tns:book>
</tns:library>

17. XML related technologies
 XPath
 XSLT (eXtensible Stylesheet Language
Transformations)
Used to translate from one form of XML to
another.
 XPointer
identify the particular point in or part of an XML
document that an XLink links to.
 XQuery

18. XML related technologies(XPath)
 XPath is a W3C Standard.
 Expression language for locating particular parts of
XML documents.
 XPath is a major element in XSLT
 XQuery and XPointer are both built on XPath
expressions.
 XML documents are viewed as a tree of nodes.
1. The root element node.
2. Element nodes.
3. Text nodes.
4. Attribute nodes.
5. Comment nodes.
6. Processing Instruction nodes.
7. Namespace nodes.

19. XPath (cont.)
 XPath expression evaluates to one of four types
1. Node set
collection of nodes returned from location path
expressions
2. Boolean
3. Number
4. String
 Location path expressions
- Form is Axis:: nodetest [predicate]
- Each location step composed of
1. Axis  defines a Node-Set relative to the
current node
2. Node test  Consists of the Node name OR
Node type
3. Predicate  optional and used to filter the node-
set.

20. Ancester-or-self axis

21. Parent axis

22. Child axis

23. Ancestor axis

24. Descendant axis

25. Following

26. Following-sibling

27. Preceding

28. Preceding-sibling

29. XPath (cont.) Node test
 Consists of the Node name OR Node type
Ex. Ex: “Element, attribute --- etc”
 Node test by type
1. node()  selects all nodes regardless of
their type.
2. text()  selects all text nodes.
3. comment()  selects all comment nodes.
4. processing-instruction()  Selects all
processing-
instruction nodes

30. XPath (cont.) Node test
<tns:book shipto="Egypt">
<tns:name>Core Java</tns:name>
<tns:chapters>12</tns:chapters>
<tns:price>35</tns:price>
</tns:book>
 If you are at the root element book
Child::*  selects 3 elements name, chapters,
price
 If you are at chapters element
child::text()  selects 3 elements
1. text node containing text before 12
2. text node with the value 12
3. text node containing text after 12

31. XPath (cont.) predicates
 Used to filter the node-set.
 Used to find a specific node or a node that
contains a specific value.
 They are always embedded in square brackets.
 Predicate types.
1. Numeric predicates.
2. Boolean predicates.
3. String predicates.
4. Node-set predicates.

32. XPath (cont.) predicates
 Numeric predicates
(+,-,*, div, mod) and the following functions
ceiling(), floor(), round(), sum()
/book/name[1]  selects the name of the first book.
 Boolean predicates
all of us know Boolean operators
/book[price < 40]  selects all books whose price is less
than 40
 String predicates  Strings in XPath is made up of
Unicode characters.
Work with = and != operators
starts-with(str1, str2), contains(str1,str2), string-length(str),
substring(str, offset, length), concat(str1, str2,…..)
 The previous predicates cannot be used in match pattern
of xsl:template

33. XPath (cont.) predicates
 Node-set predicates.
last()  the last position of the current node in
the node-set
position()  position of the current node in the
node-set.
count()  number of nodes in node-set

34. XPath Abbreviated location path
Abbreviation Expanded Form
@Name Attribute::Name
// /descendant-or-self::Node()/
. self::node()
.. parent::node()
* Matches any element
@* Matches any attribute element
Node() Matches any node of any kind

35. XML related technologies(XSLT)
 W3C standard for XML transformation
 Made of two parts.
1. XSL Transformation (XSLT).
2. XSL Formatting Objects (XSL-FO).
 Transforms XML document into
1. Another XML Document (XHTML or WML).
2. HTML document.
3. Text

36. XML related technologies(XSLT)

37. XML related technologies(XSLT)
 template
 value-of
 apply-templates
 for-each
 if
 when, choose, otherwise
 sort
 filtering

38. XML related technologies(XSLT)
 template
It is a container for a set of rules to apply actions
against the source tree to produce a result tree
 General form
<xsl:template match = “node name”
[name = “template name”] >
<!– action -->
</xsl:template>
 match uses XPath expression to match elements

39. XML related technologies(XSLT)
 value-of
Used inside template element to extract value
from the source tree and insert it in the result
tree.
 General form
<xsl:value-of select=“node-Name”/>

40. XML related technologies(XSLT)
 apply-templates
Executes templates based on the current context
and passes control over to the other template.
 The apply-template has a select attribute, which
tells the XSLT processor which nodes to apply
templates to.
 If there is no select attribute  the XSLT
processor collects all the children of the current
node and applies template to them.

41. XML related technologies(XSLT)
 call-template
call template by name as function calling.
 Used as following
<xsl:template name=“templateName”>
<!– template actions insert here -->
</xsl:template>
Syntax:
<xsl:call-template name=“templateName” >
 Ex.

42. XML related technologies(XSLT)
 if conditional processing
Perform conditional processing such as if
statement in java
<xsl:if test=“XPath expression">
some output if the expression is true
</xsl:if>
 Ex.

43. XML related technologies(XSLT)
 Iteration
iteration through node set using element for-each
<xsl:for-each select=“XPath-expression">
action insert here
</xsl:for-each>
 Ex.

44. XML related technologies(XSLT)
 Sorting
<xsl:for-each select=“XPath-expression">
<xsl:sort select=“Node or attribute“
order=“”/>
</xsl:for-each>
value of attribute order can be
ascending A-Z “default”
descending Z-A
 Ex.

45. XML related technologies(XSLT)
 Choose
- perform conditional processing
- has child elements when and otherwise
Ex.
<xsl:choose>
<xsl:when test="expression">
... some output ...
</xsl:when>
<xsl:when test="expression">
... some output ...
</xsl:when>
-----------------------
<xsl:otherwise>
... some output ....
</xsl:otherwise>
</xsl:choose>

46. XML related technologies(XSLT)
 Creating Elements and Attributes
 Creating Elements
- Dynamic way
<xsl:element name = "{Element-Name}“>
element body
</xsl:element>
- Static way
<Element-Name MyAttribute=“MyValue”>
element body
</Element-Name>
 Creating attributes
<xsl:attribute name = "{Attribute-Name}“>
Attribute Value “string”
</xsl:attribute>

47. JAXP