XML Lab Session

1
XML Lab Session

• Creating an XML document

2
Objective

• How to write an XML document?
• What are the important parts of an XML program?
• What is root element?
• What are empty elements?
• DTD
• XML Schema
• Practice 1-5

3
Example

• lt?xml version "1.0"?gt ltMy.pagegt ltheadgt lttitlegt
  My home page lt/titlegt ltheader source
  "imagehead.gif "/gt lt/headgt ltbodygt ltmain.titlegt
  Welcome to my home page lt/main.titlegt ltrule/gt ltt
  extgt ltparagt           SORRY! This page is still
  under construction. Visit this site
  soon. lt/paragt lt/textgt lt/bodygt ltfooter source
  imagefoot.gif "/gtlt/My.pagegt

4
Elements  i.e., from lttitlegt to lt/titlegt

• In XML, an element normally consists of 3 things
  
• a start tag.
• content (either text or other elements ).
• an end tag.
• Ex lttitlegt My home page lt/titlegt 

5
Empty Elements i.e., lt rule/ gt  

• Empty elements are a special case in XML. 
• XML requires you to be much more explicit when
  dealing with empty elements.
• To do so, there is a special empty tag close
  delimiter, /gt , as in the following
                              ltempty-element /gt
• You can also use an end tag instead of the
  special empty tag close delimiter. The element
  declaration                      lt graphic
  source " image.gif "/gt    is therefore
  interchangeable with                     lt
  graphic source " image.gif "gt.............lt/
  graphicgt
•  

6
Attributes i.e., ltheader source"imagehead.gif"/
gt 

• Element tags can include one or more optional or
  mandatory attributes.
• Attributes can only be specified in the element
  start tag.
• The syntax for specifying an attribute is  
• ltattribute.type.name  attribute.name
  "attribute.value" gt
• lt fruit taste "sharp" gt

7
Important!

• XML deals with multiple declaration of attributes
  in a unique manner. If an element appears once
  with one set of attributes and then appears again
  with a different set of attributes, the two sets
  of attributes are merged. 
• The first declaration of an attribute for a
  particular element is the only one that counts,
  and any other declarations are ignored.

8
Practice 1

• Using Notepad or other text editor create a XML
  document describing
• The book Harry Potter and the half-blood
  prince, author J.K. Rowling, illustrator Mary
  Grandpre, year 2006, Paperback 652 pages,
  Publisher Scholastic Paperbacks
  Language English

9
Practice 2

• Using Notepad or other text editor create a XML
  document describing an invoice. For example,
  include invoiceNumber, seller, customer, date,
  item0-itemN with quantity, type, price for each
  item

10
Practice 3

• Using Notepad or other text editor create a XML
  document describing an ebay page of an item, in
  ex. a laptop, a phone, a music player, etc.

11
DTD Review

• A DTD describes a model of the structure of the
  content of an XML document. 
• This model says what elements must be present,
  which ones are optional what their attributes
  are, and how they can be structured with relation
  to each other. 
• While HTML has only one DTD, XML allows you to
  create your own DTD's for your applications. This
  gives you complete control over the process of
  checking the content and structure of the XML
  documents created for that application. This
  checking process is called validation.

12
Simple XML DTD
  lt !DOCTYPE  DTDname options gt
13
Practice 4

• Re-do Practice 2 using DTD
• For reference, see Lecture12_XML_Structure_Present
  ation.ppt

14
Schema Review

• Schemas define the document's structure, i.e.,
• which elements are children of others. 
• the order the child elements can appear. 
• and the number of child elements. 
• Schemas specify if an element is empty or if it
  can include text. 
• Schemas can also specify default values for
  attributes. 
• Schemas are more powerful and flexible than DTDs
  and use XML syntax. 
• Schemas supports scope enabled definitions.
• Schema standards are defined by the World Wide
  Web Consortium(W3C). The W3C site provides
  comprehensive reference of XML schemas. 

15
Simple XML XML Schema
16
Practice 5

• Re-do Practice 3 using DTD
• For reference, see Lecture12_XML_Structure_Present
  ation.ppt

17
Thank You

• Source http//www.expertrating.com/courseware/XML
  Course/XML-Write-Xml-Document-3.asp