XML Training Course

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XML Training Course

• Module 4 XML Validation with XML Schemas

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What to expect this Session

• Shortcomings of DTDs
• What is an XML Schema?
• Discussion of Namespaces
• Defining Simple Elements
• Defining Attributes
• Defining Complex Elements

3
DTDs Shortcoming

• They can only validate structure of a document.
• They can not enforce any type of rules for a
  particular element.
• To enforce rules use and XML Schema

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XML Schema

• Define the structure of an XML Document
• Constrain the content of the document
• Built using predefined XML elements and
  attributes
• Also called and XSD, XML Schema Definition

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Namespaces

• A way to package XML elements together for reuse.
• Provides a way to avoid element name conflicts
• ltPropertyDestroyed xmlnsCDshttp//www.foo.com/c
  ds.xml
• xmlnsArthttp//www.
  oof.com/art.xmlgt
• ltItem id23gt
• ltobjectgtMusic CDlt/objectgt
• ltCDsArtistgtNewsboyslt/CDsArtistgt
• ltCDsTitlegtThrivelt/CDsTitlegt
• lt/objectgt
• lt/Itemgt
• ltItem id24gt
• ltobjectgtPaintinglt/objectgt
• ltArtArtistgtPablo Picassolt/ArtArtistgt
• ltArtTitlegtDon Quixotelt/ArtTitlegt
• lt/objectgt
• lt/Itemgt
• lt/ProperyDestroyedgt

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Sample XSD

• lt?xml version"1.0"?gt
• ltxsschema xmlnsxs"http//www.w3.org/2001/XMLSch
  ema" targetNamespace"http//www.acs.cc.al.us"
• xmlns"http//www.acs.cc.al.us"
  elementFormDefault"qualified"gt
• ltxselement nameMemo"gt
• ltxscomplexTypegt
• ltxssequencegt
• ltxselement nameTO" type"xsstring"/gt
• ltxselement nameCC" type"xsstring"/gt
• ltxselement nameFROM" type"xsstring"/gt
• ltxselement nameRE" type"xsstring"/gt
• ltxselement nameBODY" type"xsstring"/gt
• lt/xssequencegt
• lt/xscomplexTypegt
• lt/xselementgt
• lt/xsschemagt

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ltschemagt

• The ltschemagt element is the root element of every
  XML Schema
• The ltschemagt element may contain some attributes.
• ltxsschema xmlnsxs"http//www.w3.org/2001/XMLSch
  ema" targetNamespace"http//www.acs.cc.al.us"
• xmlns"http//www.acs.cc.al.us"
  elementFormDefault"qualified"gt

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XSD - Simple Elements

• XML Schemas define the elements of your XML
  files.
• A simple element is an XML element that can
  contain only text. It cannot contain any other
  elements or attributes

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How to define a Simple Element

• Syntax
• ltxselement name"xxx" type"yyy"/gt
• Examples

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Common Data Types

• xsstring
• xsdecimal
• xsinteger
• xsboolean
• xsdate
• xstime

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Default and Fixed Values

• Simple elements can have a default value OR a
  fixed value set
• Default The value automatically assigned to the
  element when no other value is specified
• ltxselement name"color" type"xsstring"
  default"red"/gt
• Fixed A value automatically assigned to an
  element. No other value may be specified.
• ltxselement name"color" type"xsstring"
  fixed"red"/gt

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XSD Attributes

• All attributes are declared as simple types.
• Only complex elements can have attributes!

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How to define an Attribute

• Synatax
• ltxsattribute name"xxx" type"yyy"/gt
• Example

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Default and Fixed Values

• Attributes, like simple elements, can have a
  default value OR have a fixed value.
• Default The value automatically assigned to the
  attribute when no other value is specified
• ltxsattribute namelang" type"xsstring"
  defaultEN"/gt
• Fixed A value automatically assigned to an
  attribute. No other value may be specified.
• ltxsattribute namelang" type"xsstring"
  fixedEN"/gt

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Optional and Required Attributes

• All attributes are optional by default
• To explicitly specify that the attribute is
  optional, use the "use" attribute
• ltxsattribute name"lang" type"xsstring"
  use"optional"/gt
• To make an attribute required
• ltxsattribute name"lang" type"xsstring"
  use"required"/gt

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XSD Restrictions and Facets

• Restrictions are used to control acceptable
  values for XML elements or attributes.
• Restrictions on XML elements are called facets.

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Restrictions on Values

• ltxselement name"age"gt
• ltxssimpleTypegt
• ltxsrestriction base"xsinteger"gt
  ltxsminInclusive value"0"/gt
• ltxsmaxInclusive value"100"/gt
  lt/xsrestrictiongt
• lt/xssimpleTypegt
• lt/xselementgt

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Restrictions on a set of Values

• ltxselement name"car"gt
• ltxssimpleTypegt
• ltxsrestriction base"xsstring"gt
• ltxsenumeration valueFord"/gt
  ltxsenumeration valueDodge"/gt
  ltxsenumeration valueSaturn"/gt
  lt/xsrestrictiongt
• lt/xssimpleTypegt
• lt/xselementgt

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Restrictions on a series of values

• ltxselement name"letter"gt
• ltxssimpleTypegt
• ltxsrestriction base"xsstring"gt
• ltxspattern value"a-z"/gt
• lt/xsrestrictiongt
• lt/xssimpleTypegt
• lt/xselementgt

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Restrictions on a series of values

• ltxselement name"initials"gt
• ltxssimpleTypegt
• ltxsrestriction base"xsstring"gt
• ltxspattern value"A-ZA-ZA-Z"/gt
• lt/xsrestrictiongt
• lt/xssimpleTypegt
• lt/xselementgt

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Restrictions on a series of values

• ltxselement name"initials"gt
• ltxssimpleTypegt
• ltxsrestriction base"xsstring"gt
• ltxspattern value"a-zA-Za-zA-Za-zA-Z"/gt
• lt/xsrestrictiongt
• lt/xssimpleTypegt
• lt/xselementgt

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Restrictions on a series of values

• ltxselement name"choice"gt
• ltxssimpleTypegt
• ltxsrestriction base"xsstring"gt
• ltxspattern value"xyz"/gt
• lt/xsrestrictiongt
• lt/xssimpleTypegt
• lt/xselementgt

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Restrictions on a series of values

• ltxselement name"prodid"gt
• ltxssimpleTypegt
• ltxsrestriction base"xsinteger"gt
• ltxspattern value"0-90-90-90-90-9"/gt
  
• lt/xsrestrictiongt
• lt/xssimpleTypegt
• lt/xselementgt

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Other uses for the Pattern Constraint

• ltxselement name"gender"gt
• ltxssimpleTypegt
• ltxsrestriction base"xsstring"gt
• ltxspattern value"malefemale"/gt
• lt/xsrestrictiongt
• lt/xssimpleTypegt
• lt/xselementgt

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Restrictions on White Space

• ltxselement name"address"gt
• ltxssimpleTypegt
• ltxsrestriction base"xsstring"gt
• ltxswhiteSpace value"preserve"/gt
• lt/xsrestrictiongt
• lt/xssimpleTypegt
• lt/xselementgt

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Restrictions on White Space

• ltxselement name"address"gt
• ltxssimpleTypegt
• ltxsrestriction base"xsstring"gt
• ltxswhiteSpace value"replace"/gt
• lt/xsrestrictiongt
• lt/xssimpleTypegt
• lt/xselementgt

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Restrictions on White Space

• ltxselement name"address"gt
• ltxssimpleTypegt
• ltxsrestriction base"xsstring"gt
• ltxswhiteSpace value"collapse"/gt
• lt/xsrestrictiongt
• lt/xssimpleTypegt
• lt/xselementgt

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Restrictions on Length

• ltxselement name"password"gt
• ltxssimpleTypegt
• ltxsrestriction base"xsstring"gt
• ltxslength value"8"/gt
• lt/xsrestrictiongt
• lt/xssimpleTypegt
• lt/xselementgt

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Restrictions on Length

• ltxselement name"password"gt
• ltxssimpleTypegt
• ltxsrestriction base"xsstring"gt
• ltxsminLength value"5"/gt
• ltxsmaxLength value"8"/gt
• lt/xsrestrictiongt
• lt/xssimpleTypegt
• lt/xselementgt

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DataType Restriction options
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XSD - Complex Elements

• A complex element contains other elements and/or
  attributes.
• Four kinds of Complex Elements
• Empty elements
• Elements that contain only other elements
• Elements that contain only text
• Elements that contain both other elements and
  text
• Each of these element may contain attributes as
  well.

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Complex Element Examples

• Empty Element
• ltproduct pid"1345"/gt
• Element contains only other elements
• ltemployeegt
• ltfirstnamegtJohnlt/firstnamegt
• ltlastnamegtSmithlt/lastnamegt
• lt/employeegt

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Complex Element Examples

• Element that contains only text
• ltfood type"dessert"gtIce creamlt/foodgt
• Element that is MIXED, that is, contains both
  elements and text
• ltdescriptiongt It happened on
• ltdate lang"norwegian"gt03.03.99lt/dategt ....
  lt/descriptiongt

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How to define a Complex ElementMethod 1

• Complex Element that contains only other
  elements
• ltemployeegt
• ltfirstnamegtJohnlt/firstnamegt
• ltlastnamegtSmithlt/lastnamegt
• lt/employeegt
• XML Schema
• ltxselement name"employee"gt
• ltxscomplexTypegt
• ltxssequencegt
• ltxselement name"firstname"
  type"xsstring"/gt
• ltxselement name"lastname"
  type"xsstring"/gt
• lt/xssequencegt
• lt/xscomplexTypegt
• lt/xselementgt

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How to define a Complex ElementMethod 2

• ltxselement name"employee" type"personinfo"/gt
• ltxscomplexType name"personinfo"gt
• ltxssequencegt
• ltxselement name"firstname"
  type"xsstring"/gt
• ltxselement name"lastname" type"xsstring"/gt
• lt/xssequencegt
• lt/xscomplexTypegt

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How to define a Complex ElementMethod 2

• ltxselement name"employee" type"personinfo"/gt
• ltxselement name"student" type"personinfo"/gt
• ltxselement name"member" type"personinfo"/gt
• ltxscomplexType name"personinfo"gt
• ltxssequencegt
• ltxselement name"firstname" type"xsstring"/gt
• ltxselement name"lastname" type"xsstring"/gt
• lt/xssequencegt
• lt/xscomplexTypegt

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Define an EMPTY Complex Element

• An empty complex element can contain attributes
  but it cannot have any content between the
  opening and closing tags.
• ltproduct prodid"1345" /gt

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Define an EMPTY Complex Element

• ltxselement name"product"gt
• ltxscomplexTypegt
• ltxscomplexContentgt
• ltxsrestriction base"xsinteger"gt
• ltxsattribute name"prodid
  type"xspositiveInteger"/gt
• lt/xsrestrictiongt
• lt/xscomplexContentgt
• lt/xscomplexTypegt
• lt/xselementgt

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Define a TEXT-ONLY Complex Element

• A complex text element that contains both
  attributes and text, but not other elements.
• This type contains only simple content (text and
  attributes), therefore we add a simpleContent
  element around the content. When using simple
  content, you must define an extension OR a
  restriction within the simpleContent element,
  like this

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Extension Syntax

• ltxselement name"somename"gt
• ltxscomplexTypegt
• ltxssimpleContentgt
• ltxsextension base"basetype"gt
• ....
• ....
• lt/xsextensiongt
• lt/xssimpleContentgt
• lt/xscomplexTypegt
• lt/xselementgt

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Extension Example

• Element
• ltshoesize country"france"gt35lt/shoesizegt
• Schema Definition
• ltxselement name"shoesize"gt
• ltxscomplexTypegt
• ltxssimpleContentgt
• ltxsextension base"xsinteger"gt
• ltxsattribute name"country" type"xsstring"
  /gt
• lt/xsextensiongt
• lt/xssimpleContentgt
• lt/xscomplexTypegt
• lt/xselementgt

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Define a MIXED Complex Element

• A mixed complex type element can contain
  attributes, elements, and text.
• ltlettergt
• Dear Mr.ltnamegtJohn Smithlt/namegt. Your order
  ltorderidgt1032lt/orderidgt will be shipped on
  ltshipdategt2001-07-13lt/shipdategt.
• lt/lettergt

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Define a MIXED Complex Element

• ltxselement name"letter"gt
• ltxscomplexType mixed"true"gt
• ltxssequencegt
• ltxselement name"name" type"xsstring"/gt
• ltxselement name"orderid" type"xspositiveInt
  eger"/gt
• ltxselement name"shipdate" type"xsdate"/gt
• lt/xssequencegt
• lt/xscomplexTypegt
• lt/xselementgt

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Review this Session

• Shortcomings of DTDs
• What is an XML Schema?
• Discussion of Namespaces
• Defining Simple Elements
• Defining Attributes
• Defining Complex Elements

45
Build an XML Schema