XML Schema

1
XML Schema

• CS 491/591
• Web Services

2
Design Objectives - Schema

• DTD equivalent XML based
• Data Typing
• Namespace integration
• Extensibility inheritance,complx UDF
• Programmatic access
• Stronger Content Model

3
Namespaces

• Requirement/necessity
• Declaring Namespaces
• QName
• Applying Namespaces to Elements and Attributes
• - Scoping
• - Defaulting
• - Uniqueness of Attributes

4
Element Types

• Complex Types element attribute
• Simple Types only content
• Complex Type Definition xsd,element
  declarations, attribute,pre def cmplx type,ref
• Occurrence Constraints Elements
• minOccurs
• - maxOccurs(unbounded)
• - default
• - fixed

5
Occur Constraints

• Occurrence Constraints Attributes
• - only once
• - useoptionalrequiredprohibited
• - default
• - fixed
• Invalid Combo Of Occur Constraints
• - default and fixed ME
• - Attributes - default useoptional only valid

6
Constraint Rules

• Default - Default attribute values apply when
  attributes are missing, and default element
  values apply when elements are empty.
• minOccurs,maxOccurs,and use cannot appear in
  global declarations
• Global Elements/Attributes
• Defined under schema
• No occur constraints
• No ref attribute. Refer using type attrib

7
Simple Types

• Built in and Derived
• Facets length,minLength,maxLength,enumeration,pa
  ttern,whitespace,maxInclusive,maxExclusive,minIncl
  usive,minExclusive,totalDigits,fractionDigits
• Another Classification
• - Atomic
• - List
• - Union
• Anonymous Type Definition - Saves naming and
  referring

8
Element Content

• Element
• Mixed
• Empty
• Simple(char data)

9
Constraining Content

• Choice
• Group
• Sequence
• All
• - Any order
• applicable to top level content of an element

10
Namespace

• targetNameSpace
• Qualified and unqualified names