This document discusses the differences between well-formed XML and valid XML. It defines well-formed XML as following all XML syntax rules, while valid XML also conforms to constraints defined in a DTD or XML schema. It provides examples of a well-formed XML document describing a t-shirt and a valid XML document for a contact list defined by a DTD. The document clarifies that not all well-formed XML is valid and that valid XML is also well-formed. It contrasts their treatment of advanced features and constraint support.

1. Prepared by
Dr.M.Kaliappan.,M.E.,Ph.D
Associate Professor
Dept. of Computer Science and Engineering
Ramco Institute of Technology
Rajapalayam, Tamilnadu, India
Email: kaliappan@ritrjpm.ac.in
Well-formed XML and valid XML
documents

2. Recap
Date: 08.07.2019
XML
XML delimiters characters:<?xml version=”1.0”?>
The XML document structure consists of
The XML declaration
The Document Type Declaration
The element data
The attribute data
The character data or XML content

3. Well-formed XML
• An XML document is well formed if it follows
all the preceding syntax rules of XML.
• On the other hand, if it includes inappropriate
markup that cannot be processed by XML
parsers, the document cannot be considered
well formed.

4. A well formed XML document for describe a T-shirt
<?xml version=”1.0”?>
<Tshirt>
<model> Zippy Tee </model>
<brand> Lee </brand>
<price currency= ”USD” >14.99</price>
<fabric content= ”60%” >cotton</fabric>
<fabric content= ”40%” >polyester</fabric>
<options>
<colorOptions>
<color>red</color>
<color>white</color>
</colorOptions>
<sizeOptions>
<size>Medium</size>
<size>Large</size>
</sizeOptions>
</options>
<description>
This is a sports giant brand
</description>
</Tshirt>
XML Declaration
Root element
Child element
Attribute
value

5. Valid XML documents
• A well-formed XML document is considered
valid only if it contains a proper Document
Type declaration and if the document obeys
the constraints of that declaration .
• The constraints of the declaration will be
expressed as a DTD or an XML Schema

6. Ex: Valid XML document : contactlist.xml
<?xml version=”1.0”?>
<!DOCTYPE contactlist SYSTEM “contactlist.dtd”>
<contactlist>
<fullname>Bobby Soninlaw</fullname>
<address>
<addressline1>101 South Street</addressline1>
<addressline2>Apartment #2</addressline2>
</address>
<phone>(405) 555-1234</phone>
<email>bs@mail.com</email>
</contactlist>
<!ELEMENT contactlist (fullname, address, phone, email) >
<!ELEMENT fullname (#PCDATA)>
<!ELEMENT address (addressline1, addressline2)>
<!ELEMENT addressline1 (#PCDATA)>
<!ELEMENT addressline2 (#PCDATA)>
<!ELEMENT phone (#PCDATA)>
<!ELEMENT email (#PCDATA)>
contactlist.dtd

7. Is this a “valid" XML document?contactlist.xml
<?xml version=”1.0”?>
<!DOCTYPE contactlist SYSTEM “contactlist.dtd”>
<contactlist>
<firstname>Bobby </firstname>
<fullname>Bobby Soninlaw</fullname>
<address>
<addressline1>101 South Street</addressline1>
<addressline2>Apartment #2</addressline2>
</address>
<phone>(405) 555-1234</phone>
<pincode>626125</pincode>
<email>bs@mail.com</email>
</contactlist>
<!ELEMENT contactlist (fullname, address, phone, email) >
<!ELEMENT fullname (#PCDATA)>
<!ELEMENT address (addressline1, addressline2)>
<!ELEMENT addressline1 (#PCDATA)>
<!ELEMENT addressline2 (#PCDATA)>
<!ELEMENT phone (#PCDATA)>
<!ELEMENT email (#PCDATA)>
contactlist.dtd

8. Well-Formed Document Valid XML Document
Well-formed documents follow all the
syntax rules of XML.
An XML document that conforms to
DTD or an XML Schema is said to be
valid XML document.
Not all well-formed XML documents
are valid XML document.
A valid XML document is also well-
formed.
Well-formed XML documents are
designed for use without any
constraints
Valid XML documents explicitly require
constraint mechanisms
It does not support advanced feature It support advanced features such as
linking mechanisms, value and range
bounding, and data typing
Difference between well-formed and valid" XML document

9. Class poll
1. Is this a "well formed" XML document?
<?xml version="1.0"?>
<message>
<to>Tove</to>
<from>Jani</from>
<heading>Reminder</heading>
<body>Don't forget me this weekend!</body>

10. 2. Well formed XML document means
A. it contains a root element
B. it contain an element
C. it contains one or more elements
D. must contain one or more elements and root
element must contain all other elements

11. 2. Valid XML document means (most appropriate)
A. the document has root element
B. the document contains at least one or more root
element
C. the XML document has DTD associated with it & it
complies with that DTD
D. Each element must nest inside any enclosing
element property

12. 3. XML preserves white spaces
–True
–false

13. 4. What does DTD stand for?
– Direct Type Definition
– Dynamic Type Definition
– Document Type Definition

14. 5. How XML describe data
– XML uses a DTD to describe data
– XML uses a description node to describe data
– XML uses XSL to describe data

15. Exercise
• Create a valid xml document for students profile