XML schemas define the structure and format of XML documents. They validate that an XML document complies with the specified structure and elements. Key components of an XML schema include element definitions, attribute definitions, annotations, and type definitions. Schemas use XML syntax to declare elements, attributes, and other components, unlike DTD syntax.

1. Schema Structure
by: Vijay Kumar Verma (VJY)

2. Objective
Schema
Component of Schema

3. What is Xml Schema?
α “A structured framework or plan”.
α XML Schema was originally proposed by
Microsoft, but became an official W3C
recommendation in May 2001.
α “XML Schemas,” we usually mean the W3C
XML Schema Language.
α Also known as “XML Schema Definition”
language, or XSD.

4. What is Xml Schema? (continue)
α An XML schema language is a formalization of
the constraints, expressed as rules or a model
of structure, that apply to a class of XML
documents. It validate the XML document.
α XML Schema documents (ie: XSD) are used to
define and validate the content and structure
of XML data.

5. Why XMLSchema?
Information
Structure
Format
Traditional Document:
Everything is clumped
together
Information
Structure
Format
“Fashionable” Document: A document
is broken into discrete parts, which can
be treated separately

6. XMLSchema Syntax
α XML schema use xml syntax for there
declaration of schema, unlike DTD syntax
<!ELEMENT first (#PCDATA)>
α Same in XSD is defined using
<element name="first" type="string"/>

7. Schema Components
Schema Elements
Element Definition
Attribute Definition
Annotations
Type Definition

8. SCHEMA ELEMENTS
α <schema> is the root element.
α It contain namespace to add the xml
schema vocabularies.
α Syntax
<schema targetNamespace=”URI”
attributeFormDefault=“qualified or unqualified”
elementFormDefault=“qualified or unqualified”
version=”version number”>
α Example:
<xs:schema xmlns:xs=”http://www.w3.org/2001/XMLSchema”>

9. ELEMENT DEFINITION
α Basic building block of our XML files.
α Syntax for Schema Element:
<xs:element name=“element-name”
type=“data-type”
default|fixed=“value” />
α Example
<xs:element name=“name” type=“xs:string”/>
<xs:element name=“Colour” type=“xs:string” default=“red” />
α Global Declaration
α Local Declarattion

10. EXAMPLE
<?xml version=“1.0”?>
<schema xmlns=“http://www.w3.org/2001/XMLSchema”
xmlns:target=“http://www.example.com/name”
targetNamespace=“http://www.example.com/name”
elementFormDefault=“qualified”>
<element name=“name”>
<complexType>
<sequence>
<element name=“first” type=“string”/>
<element name=“middle” type=“string”/>
<element name=“last” type=“string”/>
</sequence>
<attribute name=“title” type=“string”/>
</complexType>
</element>
</schema>

11. ATTRIBUTE DEFINITATION
α Simple element have not attribute, if
yes, are considered as complex type.
α Syntax for attribute definition:
<xs:attribute name=“attribute-name”
type=“data-type”
default|fixed=“value”
use=“optional|required”/>
α Example
Xml file <lastname lang="EN">Smith</lastname>
In Schma <xs:attribute name="lang" type="xs:string" />

12. ANNOTATIONS
α An annotation is information for human
and/or mechanical consumers. The
interpretation of such information is not
defined in this specification.
α These are metadata.
α Annotation Syntax:
<xs:annotation>
<xs:documentation>…</xs:documentation>
<xs:appinfo>…</xs:appinfo>
</xs:annotation>
α Here appinfo for mechine and
documentation for user.

13. ANNOTATION EXAMPLE
<annotation>
<appinfo source=”name-sample.xml”/>
<documentation xml:lang=”en”>
The name vocabulary was created
for an example of a DTD. We have
recycled it into an XML Schema.
</documentation>
</annotation>

14. TYPE DEFINITION
α XML schema have Many built-in Data types
α Facility to create User define data types.
α All type declaration classified in
 Simple Type
 Complex Type

15. SIMPLE TYPE
<xs:element name=“price”>
<xs:simpleType>
<xs:restriction base=“xs:string”>
<xs:pattern
value=”$[0-9]{1,4}.[0-9]{2}”/>
</xs:restriction>
</xs:simpleType>
</xs:element>

16. COMPLEX TYPE
<xs:element name=”bookInfo”>
<xs:complexType>
<xs:sequence>
<xs:element ref=”title”/>
<xs:element ref=”author”/>
<xs:element ref=”publisher”/>
<xs:element ref=”isbn”/>
</xs:sequence>
</xs:complexType>
</xs:element>