Introduction to XML and DTD

1
Unit 1

• Introduction to XML and DTD

2
Section Objectives

• Roots of XML
• XML Document Structure
• Document Type Definition (DTD)

3
Mark-up Languages

• HTML Familiar
• Purely Sequential
• Paragraph Tag ltPgt
• Problem Content Wrapped in Mark-up

3
4
Roots of XML
Roots of XML

• SGML
• HTML
• XML
• Document Type Definitions
• Valid documents

4
5
Roots of XML
5
6
Introducing XML
Example1.xml
Example1.html
6
7
Introducing XML
XML in IE5 browser
7
8
Exercise 1

• Using a simple text editor (ex. notepad.exe),
  modify the structure of the XML document from
  Example1.xml so that the cars have their own
  enclosing ltcargtlt/cargt tags.
• Edit the file Exercise1.xml
• View the result in IE5.
• How do you know if it is well-formed?

8
9
Section Objectives

• Roots of XML
• XML Document Structure
• Document Type Definition (DTD)

10
Structure of XML Document
Root 0
A child has only ONE parent Child 0.1.2 for
example has parent 0.1
10
11
Structure of XML Document
Book
Chapter 1
Section1 for Chapter 1
Chapter 1 Heading
Section 1 Heading
Paragraph 1
11
12
Structure of XML Document
Book
Chapter
Section
Chapter Heading
Paragraph
Section Heading
Entries
Text
Figure
12
13
Sample Book XML

• ltbookgt
• ltchaptergt
• ltchapter.headinggtCONTENT
• lt/chapter.headinggt
• ltsectiongt
• ltsection.headinggtCONTENT
• lt/section.headinggt
• ltparagraphgt
• lttextgtCONTENTlt/textgt
• ltimagegtCONTENTlt/imagegt
• lttextgtCONTENTlt/textgt
• ...
• lt/paragraphgt
• lt/sectiongt
• lt/chaptergt
• lt/bookgt

Example2.xml
13
14
XML Elements

• Opening tag
• Content
• Closing tag
• Empty Element

14
15
XML Attributes

• Element can have 0 or more
• Values must be in quotes
• Associate data with element

15
16
Well Formed XML

• There must be a single root element
• All elements must be properly nested
• Element tags must match (lttaggtlt/taggt)
• Empty element may have a single tag definition
  (lttag/gt)
• Valid names start with alphabetic or a _
  (underscore) followed by any combination of
  letters, digits, hyphens, full stops or colons.
  Colons have a special meaning in allowing a name
  to be made unique through namespaces
• There must be no white space characters (space,
  tab or new line characters)
• The content between tags must not contain
  explicitly the following characters lt gt

16
17
Other XML Elements and References

• CDATA
• Processing Instructions
• Comments

17
18
Other XML Elements and References

• XML Declaration
• Version
• External DTD
• Character encoding

18
19
Other XML Elements and References

• Entities
• Character References
• Elements or Attributes
• White space

19
20
Section Objectives

• Roots of XML
• XML Document Structure
• Document Type Definition (DTD)

21
Introduction to DTD

• Structured Declarations
• Well formed XML prior discussion
• Valid XML current discussion
• Do not conform to XML syntax
• Knowing the DTD allows you to create valid XML
  documents

21
22
Advantages of DTD

• Obeys DTD - it is valid and well formed
• Specification known by developer
• Reliable Communication between applications
• Specify default values

22
23
XML Document Structure
23
24
The Basic Declaration
lt!DOCTYPE root_name . declarations of
elements, attributes and entities . gt
lt!DOCTYPE root_name SYSTEM locationgt
24
25
The Basic Declaration
lt!DOCTYPE rootname lt!ELEMENT rootname
gt lt!ELEMENT gt lt!ELEMENT gt lt!ATTLIST
gt lt!ATTLIST gt lt!ATTLIST gt lt!ENTITY
gt lt!ENTITY gt lt!NOTATION gt lt!NOTATION
gt etc. etc. gt
25
26
Declaring Elements

• Syntax
• Sequence
• Selection

26
27
Declaring Elements

• Optional
• Iteration

27
28
Content Definitions

• Elements
• PCDATA
• EMPTY
• ANY

28
29
Entities and Entity Declarations

• Standard Entities
• General Entities

29
30
Entities and Entity Declarations

• Character Entities
• Escaping Characters
• Parameter Entities

30
31
Notations
ltNOTATION jpg SYSTEM D\Program
Files\Plus!\Microsoft Internet\iexplore.exegt
31
32
Defining Attributes
lt!ATTLIST element_name attribute_name
attribute type default values/requirements gt
ltbook price "12.45" currency "GBP"gtlt/bookgt
32
33
Attribute Requirements

• REQUIRED
• FIXED
• IMPLIED

33
34
Attribute Types

• CDATA
• Enumerated Types
• ID and IDREF

34
35
Attribute Types

• NMTOKEN
• lt!ATTLIST book date_in NMTOKEN IMPLIEDgt
•  
• ltbook date_in "12-09-1999"gtlt/bookgt
• lt!ATTLIST book owners NMTOKENS REQUIREDgt
•  
• ltbook owners "Shakespeare Bacon"gtlt/bookgt

35
36
Attribute Types

• ENTITY
• lt!ENTITY fig5.jpg SYSTEM "E\XML Course\fig
  5.0.jpg" NDATA jpggt
• ltfigure image "fig5.jpg"/gt
• lt!ELEMENT figure EMPTYgt
• lt!ATTLIST figure image ENTITY REQUIREDgt
• lt!ENTITY fig5.jpg SYSTEM "E\XML Course\fig
  5.0.jpg" NDATA jpggt

36
37
Attribute Types

• NOTATION
• lt!NOTATION jpg SYSTEM "D\Program
  Files\Plus!\MicrosoftInternet\iexplore.exe"gt

37
38
Normalisation and White Space

• Quotes Stripped
• Entities Replaced
• xmlspace

38