XML Schema XML Schema Vinod Kumar Kayartaya
XML Schema Vinod Kumar Kayartaya. What is XML Schema? XML Schema is an XML based alternative to DTD An XML schema describes the structure of an XML.
Jan 16, 2016
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XML SchemaXML Schema
Vinod Kumar Kayartaya
What is XML Schema?What is XML Schema?
XML Schema is an XML based alternative to DTD
An XML schema describes the structure of an XML document
The purpose of an XML Schema is to define the legal building blocks of an XML document, just like a DTD
XML Schemas support data types, which DTDs do not
The XML Schema language is also referred to as XML Schema Definition (XSD)
XML documents can have a reference to a DTD or an XML Schema
What Does XML Schema Define?What Does XML Schema Define?
An XML Schema:– defines elements that can appear in a document – defines attributes that can appear in a document – defines which elements are child elements – defines the sequence in which the child elements
can appear – defines the number of child elements – defines whether an element is empty or can
include text – defines data types for elements and attributes – defines default values for elements and
attributes
XML Schema SpecificationXML Schema Specification
XML Schema specification consists of two parts:– Structures– Datatypes
http://www.w3.org/TR/xmlschema-0/ (Primer)
http://www.w3.org/TR/xmlschema-1/ (Structures)
http://www.w3.org/TR/xmlschema-2/ (Datatypes)
XML TermsXML Terms
Instance Document – an XML document that is valid according to a particular schema
Schema – the XML document that has structural rules defined for an XML document
Instance Document (.xml file)
Schema (.xsd file)
Schema Validator
Building Blocks of SchemaBuilding Blocks of Schema
Element declarations – Complex type definitions – Simple type definitions
Attribute declarations
Schema ElementsSchema Elements
Simple Elements:– they do not contain other elements<xs:element name="name" type="type"/>
Complex Elements– they contain other elements<xs:element name="name">
<xs:complexType> . . element content . </xs:complexType> </xs:element>
Schema – Example 1Schema – Example 1<!ELEMENT note (to, from,
heading, body)> <!ELEMENT to (#PCDATA)> <!ELEMENT from (#PCDATA)> <!ELEMENT heading (#PCDATA)> <!ELEMENT body (#PCDATA)>
<!ELEMENT note (to, from, heading, body)>
<!ELEMENT to (#PCDATA)> <!ELEMENT from (#PCDATA)> <!ELEMENT heading (#PCDATA)> <!ELEMENT body (#PCDATA)>
<?xml version="1.0"?> <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"><xsd:element name="note"> <xsd:complexType> <xsd:sequence> <xsd:element name="to" type="xsd:string"/> <xsd:element name="from" type="xsd:string"/> <xsd:element name="heading" type="xsd:string"/> <xsd:element name="body" type="xsd:string"/> </xsd:sequence> </xsd:complexType> </xsd:element></xsd:schema>
<?xml version="1.0"?> <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"><xsd:element name="note"> <xsd:complexType> <xsd:sequence> <xsd:element name="to" type="xsd:string"/> <xsd:element name="from" type="xsd:string"/> <xsd:element name="heading" type="xsd:string"/> <xsd:element name="body" type="xsd:string"/> </xsd:sequence> </xsd:complexType> </xsd:element></xsd:schema>
<?xml version="1.0"?> <note> <to>Mary</to> <from>John</from> <heading>Reminder</heading> <body>Don't forget me this
weekend!</body> </note> www.w3schools.com
<?xml version="1.0"?> <note> <to>Mary</to> <from>John</from> <heading>Reminder</heading> <body>Don't forget me this
weekend!</body> </note> www.w3schools.com
The NamespacesThe Namespaces
XML Schema Namespace– The elements and datatypes that are used
to construct schemas (schema, element, complexType, sequence, string, etc.) come from the http://www.w3.org/2001/XMLSchema namespacehttp://www.w3.org/2001/XMLSchema
elementcomplexType
schema
sequence
string
integer
boolean
The Namespaces…The Namespaces…
Reference to the schema in the instance document
<?xml version="1.0"?><note xmlns:xsi=
"http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation= "note.xsd">
<to>Mary</to> <from>John</from> <heading>Reminder</heading> <body>Don't forget me this weekend!</body> </note>
Reference to the schema in the instance document
<?xml version="1.0"?><note xmlns:xsi=
"http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation= "note.xsd">
<to>Mary</to> <from>John</from> <heading>Reminder</heading> <body>Don't forget me this weekend!</body> </note>
The Namespaces…The Namespaces…
XML Schema-instance Namespace
http://www.w3.org/2001/XMLSchema-instance
schemaLocationtype
noNamespaceSchemaLocation
nil
The Levels of ValidationThe Levels of Validation
note.xml note.xsd XMLSchema.xsd(schema-for-schemas)
Validate that note.xmlconforms to the rules describedin note.xsd
Validate that note.xsd is a valid schema document, i.e., it conformsto the rules described in theschema-for-schemas
Common XML Schema Data TypesCommon XML Schema Data Types
XML Schema has a lot of built-in data types. Some of them:– xs:string – xs:decimal – xs:integer – xs:boolean – xs:date – xs:time
Schema – Example 2Schema – Example 2
<!ELEMENT BookStore (Book)+>
<!ELEMENT Book (Title, Author, Date, ISBN, Publisher)>
<!ELEMENT Title (#PCDATA)>
<!ELEMENT Author (#PCDATA)>
<!ELEMENT Date (#PCDATA)>
<!ELEMENT ISBN (#PCDATA)>
<!ELEMENT Publisher (#PCDATA)>
<!ELEMENT BookStore (Book)+>
<!ELEMENT Book (Title, Author, Date, ISBN, Publisher)>
<!ELEMENT Title (#PCDATA)>
<!ELEMENT Author (#PCDATA)>
<!ELEMENT Date (#PCDATA)>
<!ELEMENT ISBN (#PCDATA)>
<!ELEMENT Publisher (#PCDATA)>
Schema – Example 2…Schema – Example 2…<?xml version="1.0"?><xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <xsd:element name="BookStore"> <xsd:complexType> <xsd:sequence> <xsd:element ref="Book" minOccurs="1" maxOccurs="unbounded"/> </xsd:sequence> </xsd:complexType> </xsd:element> <xsd:element name="Book"> <xsd:complexType> <xsd:sequence> <xsd:element ref="Title" minOccurs="1" maxOccurs="1"/> <xsd:element ref="Author" minOccurs="1" maxOccurs="1"/> <xsd:element ref="Date" minOccurs="1" maxOccurs="1"/> <xsd:element ref="ISBN" minOccurs="1" maxOccurs="1"/> <xsd:element ref="Publisher" minOccurs="1" maxOccurs="1"/> </xsd:sequence> </xsd:complexType> </xsd:element> <xsd:element name="Title" type="xsd:string"/> <xsd:element name="Author" type="xsd:string"/> <xsd:element name="Date" type="xsd:string"/> <xsd:element name="ISBN" type="xsd:string"/> <xsd:element name="Publisher" type="xsd:string"/></xsd:schema>
<?xml version="1.0"?><xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <xsd:element name="BookStore"> <xsd:complexType> <xsd:sequence> <xsd:element ref="Book" minOccurs="1" maxOccurs="unbounded"/> </xsd:sequence> </xsd:complexType> </xsd:element> <xsd:element name="Book"> <xsd:complexType> <xsd:sequence> <xsd:element ref="Title" minOccurs="1" maxOccurs="1"/> <xsd:element ref="Author" minOccurs="1" maxOccurs="1"/> <xsd:element ref="Date" minOccurs="1" maxOccurs="1"/> <xsd:element ref="ISBN" minOccurs="1" maxOccurs="1"/> <xsd:element ref="Publisher" minOccurs="1" maxOccurs="1"/> </xsd:sequence> </xsd:complexType> </xsd:element> <xsd:element name="Title" type="xsd:string"/> <xsd:element name="Author" type="xsd:string"/> <xsd:element name="Date" type="xsd:string"/> <xsd:element name="ISBN" type="xsd:string"/> <xsd:element name="Publisher" type="xsd:string"/></xsd:schema>
Reusing declarations with the
ref attribute
Schema – Example 2…Schema – Example 2…
<?xml version="1.0"?><xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema“><xsd:element name="BookStore"> <xsd:complexType> <xsd:sequence> <xsd:element name="Book" maxOccurs="unbounded"> <xsd:complexType> <xsd:sequence> <xsd:element name="Title" type="xsd:string"/> <xsd:element name="Author" type="xsd:string"/> <xsd:element name="Date" type="xsd:string"/> <xsd:element name="ISBN" type="xsd:string"/> <xsd:element name="Publisher" type="xsd:string"/> </xsd:sequence> </xsd:complexType> </xsd:element> </xsd:sequence> </xsd:complexType></xsd:element></xsd:schema>
<?xml version="1.0"?><xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema“><xsd:element name="BookStore"> <xsd:complexType> <xsd:sequence> <xsd:element name="Book" maxOccurs="unbounded"> <xsd:complexType> <xsd:sequence> <xsd:element name="Title" type="xsd:string"/> <xsd:element name="Author" type="xsd:string"/> <xsd:element name="Date" type="xsd:string"/> <xsd:element name="ISBN" type="xsd:string"/> <xsd:element name="Publisher" type="xsd:string"/> </xsd:sequence> </xsd:complexType> </xsd:element> </xsd:sequence> </xsd:complexType></xsd:element></xsd:schema>
Inline Element Declarations
Anonymous type
Occurrence Constraints on Occurrence Constraints on ElementsElements The attributes minOccurs and maxOccurs can
be used to indicate the number of times an element can appear
The default value for both the attributes minOccurs and maxOccurs is 1. If both the attributes are omitted, the element should appear exactly once.
Default and Fixed Values for Simple Default and Fixed Values for Simple Elements Elements
Elements can have either a default value OR a fixed value set
A default value is automatically assigned to the element when no other value is specified
A fixed value is also automatically assigned to the element when no other value is specified
But, unlike default values, if you specify another value than the fixed value, the document is considered invalid
<xs:element name="color" type="xs:string" default="red"/>
<xs:element name="color" type="xs:string" fixed="red"/>
<xs:element name="color" type="xs:string" default="red"/>
<xs:element name="color" type="xs:string" fixed="red"/>
Complex TypesComplex Types
Complex Types – Named TypesComplex Types – Named Types
The complex type definitions create new complex types, which can be reused in the element declarations
New complex types are defined using the complexType element
ComplexType definition typically contains a set of – element declarations, – element references, and – attributes declarations
Example –Complex (Named) Type Example –Complex (Named) Type DefinitionDefinition
Instance Document
<?xml version="1.0"?>
<note>
<to>Mary</to>
<from>John</from>
<heading>Reminder</heading>
<body>Don't forget me this weekend!</body>
</note>
Instance Document
<?xml version="1.0"?>
<note>
<to>Mary</to>
<from>John</from>
<heading>Reminder</heading>
<body>Don't forget me this weekend!</body>
</note>
Example –Complex (Named) Type Example –Complex (Named) Type Definition…Definition…
<?xml version="1.0"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="note" type="noteType"/>
<xs:complexType name="noteType">
<xs:sequence>
<xs:element name="to" type="xs:string"/>
<xs:element name="from" type="xs:string"/>
<xs:element name="heading" type="xs:string"/>
<xs:element name="body" type="xs:string"/>
</xs:sequence>
</xs:complexType>
</xs:schema>
<?xml version="1.0"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="note" type="noteType"/>
<xs:complexType name="noteType">
<xs:sequence>
<xs:element name="to" type="xs:string"/>
<xs:element name="from" type="xs:string"/>
<xs:element name="heading" type="xs:string"/>
<xs:element name="body" type="xs:string"/>
</xs:sequence>
</xs:complexType>
</xs:schema>
Simple TypesSimple Types
Simple TypesSimple Types
Simple types could be – Built-in simple types (xs:string, xs:int, etc.)– Those derived from simple types or
existing derived ones• Deriving can be done by restricting the values
that the new type can take on, as a subset of the values of the existing simple type
• Restricting the range of values for the new simple type can be done with the xsd:restriction element
• Facets constrain the values
Derived Simple TypesDerived Simple Types
A new simple type salaryType derived from the integer type:
<xsd:element name="salary" type="salaryType"/>
<xsd:simpleType name="salaryType">
<xsd:restriction base="xsd:integer">
<xsd:minInclusive value="5000"/>
<xsd:maxInclusive value="10000"/>
</xsd:restriction>
</xsd:simpleType>
<xsd:element name="salary" type="salaryType"/>
<xsd:simpleType name="salaryType">
<xsd:restriction base="xsd:integer">
<xsd:minInclusive value="5000"/>
<xsd:maxInclusive value="10000"/>
</xsd:restriction>
</xsd:simpleType>
Derived Simple Types…Derived Simple Types…
A new simple type bookType derived using the enumeration facet
<xs:element name="book" type="bookType"/><xs:simpleType name="bookType"> <xs:restriction base="xs:string"> <xs:enumeration value="Technical"/> <xs:enumeration value="Managerial"/> <xs:enumeration value="Fiction"/> </xs:restriction> </xs:simpleType>
<xs:element name="book" type="bookType"/><xs:simpleType name="bookType"> <xs:restriction base="xs:string"> <xs:enumeration value="Technical"/> <xs:enumeration value="Managerial"/> <xs:enumeration value="Fiction"/> </xs:restriction> </xs:simpleType>
The type "carType" can be
used by other elements because it is not a part of
the "car" element
The type "carType" can be
used by other elements because it is not a part of
the "car" element
An Anonymous Simple Type An Anonymous Simple Type
This simple type cannot be reused as it is part of the element declaration
<xs:element name="book"> <xs:simpleType> <xs:restriction base="xs:string"> <xs:enumeration value="Technical"/> <xs:enumeration value="Managerial"/> <xs:enumeration value="Fiction"/> </xs:restriction> </xs:simpleType></xs:element>
<xs:element name="book"> <xs:simpleType> <xs:restriction base="xs:string"> <xs:enumeration value="Technical"/> <xs:enumeration value="Managerial"/> <xs:enumeration value="Fiction"/> </xs:restriction> </xs:simpleType></xs:element>
Summary – Declaring ElementsSummary – Declaring Elements
A simple type(e.g., xs:string)or the name ofa complexType(e.g., noteType)
<xs:element name="name" minOccurs="int" maxOccurs="int"> <xs:complexType> … </xs:complexType></xs:element>
<xs:element name="name" minOccurs="int" maxOccurs="int"> <xs:complexType> … </xs:complexType></xs:element>
<xs:element name="name" type="type" minOccurs="int" maxOccurs="int"/>
<xs:element name="name" type="type" minOccurs="int" maxOccurs="int"/>
A nonnegative integer
A nonnegative integer or the value “unbounded”
Summary – Declaring Elements…Summary – Declaring Elements…
<xs:element name="name" minOccurs="int" maxOccurs="int"> <xs:simpleType> … </xs:simpleType></xs:element>
<xs:element name="name" minOccurs="int" maxOccurs="int"> <xs:simpleType> … </xs:simpleType></xs:element>
Summary – Defining Reusable Summary – Defining Reusable TypesTypes
<xs:complexType name="name"> <xs:sequence> … </xs:sequence></xs:complexType>
<xs:complexType name="name"> <xs:sequence> … </xs:sequence></xs:complexType>
<xs:simpleType name="name"> <xs:restriction> … </xs:restriction></xs:simpleType>
<xs:simpleType name="name"> <xs:restriction> … </xs:restriction></xs:simpleType>
Schema AttributesSchema Attributes
An element that has an attribute should always be declared as complex type
The attribute declaration must reference simple types always
<?xml version="1.0"?>
<book category="technical"
xmlns:xsi=
"http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation= "book.xsd">
<title>XML Schemas</title>
<ISBN>200-ABCD</ISBN>
<price currency="USD">12.5</price>
</book>
<?xml version="1.0"?>
<book category="technical"
xmlns:xsi=
"http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation= "book.xsd">
<title>XML Schemas</title>
<ISBN>200-ABCD</ISBN>
<price currency="USD">12.5</price>
</book>
Book.xml
Schema Attributes…Schema Attributes…<?xml version="1.0"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="book" type="bookType"/>
<xs:complexType name="bookType">
<xs:sequence>
<xs:element name="title" type="xs:string"/>
<xs:element name="ISBN" type="ISBNType"/>
<xs:element name="price" type="priceType"/>
</xs:sequence>
<xs:attribute name="category" type="xs:string"/>
</xs:complexType>
<xs:simpleType name="ISBNType">
<xs:restriction base="xs:string">
<xs:pattern value="\d{3}-[A-Z]{4}"/>
</xs:restriction>
</xs:simpleType>
<xs:complexType name="priceType">
<xs:simpleContent>
<xs:extension base="xs:decimal">
<xs:attribute name="currency" type="xs:string"/>
</xs:extension>
</xs:simpleContent>
</xs:complexType>
</xs:schema>
<?xml version="1.0"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="book" type="bookType"/>
<xs:complexType name="bookType">
<xs:sequence>
<xs:element name="title" type="xs:string"/>
<xs:element name="ISBN" type="ISBNType"/>
<xs:element name="price" type="priceType"/>
</xs:sequence>
<xs:attribute name="category" type="xs:string"/>
</xs:complexType>
<xs:simpleType name="ISBNType">
<xs:restriction base="xs:string">
<xs:pattern value="\d{3}-[A-Z]{4}"/>
</xs:restriction>
</xs:simpleType>
<xs:complexType name="priceType">
<xs:simpleContent>
<xs:extension base="xs:decimal">
<xs:attribute name="currency" type="xs:string"/>
</xs:extension>
</xs:simpleContent>
</xs:complexType>
</xs:schema>
Book.xsd
Attribute DefaultsAttribute Defaults
Attributes can have either a default value OR a fixed value specified
<xs:attribute name="currency" type="xs:string" default="INR"/>
<xs:attribute name="currency" type="xs:string" default="INR"/>
<xs:attribute name="currency" type="xs:string" fixed="INR"/>
<xs:attribute name="currency" type="xs:string" fixed="INR"/>
Attribute OccurrenceAttribute Occurrence
Attribute occurrence (once or none) is indicated by use attribute
Values for use attribute:– required, optional, prohibited– Default value is optional
<xs:attribute name="currency" type="xs:string" use="optional"/>
<xs:attribute name="currency" type="xs:string" use="optional"/>
<xs:attribute name="currency" type="xs:string" use="required"/>
<xs:attribute name="currency" type="xs:string" use="required"/>
Complex Types – More Complex Types – More Element Content ModelsElement Content Models
Complex Elements – More Complex Elements – More ExamplesExamples Element Contents
– Elements containing only a simple type value (text)
– Elements containing other elements– Elements containing other elements and
attributes– Empty elements (with or without
attributes)– Elements containing simple type value
(text) and attributes
Empty ElementsEmpty Elements
The existence of an attribute makes an element complex type, though it may not contain any content at all
<phone ftype="home" number="238654"/><phone ftype="home" number="238654"/>
<xs:element name="phone"><xs:complexType> <xs:attribute name="ftype" type="xs:string"/> <xs:attribute name="number" type="xs:string"/>
</xs:complexType></xs:element>
<xs:element name="phone"><xs:complexType> <xs:attribute name="ftype" type="xs:string"/> <xs:attribute name="number" type="xs:string"/>
</xs:complexType></xs:element>
Element with Text and Attribute Element with Text and Attribute
<xs:element name="phone"> <xs:complexType> <xs:simpleContent>
<xs:extension base="xs:string"> <xs:attribute name="ftype" type="xs:string"/> </xs:extension> </xs:simpleContent> </xs:complexType> </xs:element>
<xs:element name="phone"> <xs:complexType> <xs:simpleContent>
<xs:extension base="xs:string"> <xs:attribute name="ftype" type="xs:string"/> </xs:extension> </xs:simpleContent> </xs:complexType> </xs:element>
<phone ftype="home">347563256</phone> <phone ftype="home">347563256</phone>
Using anyTypeUsing anyType
anyType allows for no constraints on the content at all
If you do not specify any type in the declaration, it defaults to anyType
<xs:element name="elem1" type="xs:anyType"/> <xs:element name="elem1" type="xs:anyType"/>
<xs:element name="elem1"/> <xs:element name="elem1"/>
Element Occurrence – Order Element Occurrence – Order IndicatorsIndicators You can use the following indicators to
mention how the elements should occur within a complex element/type– All
• Indicates that the child elements can appear in any order, but each can occur at most once (minOccurs=0, maxOccurs=1)
– Choice• Indicates either of the child elements only can
occur
– Sequence• Indicates that the child elements should occur
only in the order specified
Element Occurrence Indicator - AllElement Occurrence Indicator - All
<?xml version="1.0"?>
<PersonInfo
xmlns:xsi= "http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation= "personinfo-all.xsd">
<person>
<name>Ram</name>
<title>Executive</title>
<dept>Sales</dept>
<email>[email protected]</email>
<phone>8723453194</phone>
</person>
<person>
<name>Sham</name>
<title>Manager</title>
<dept>Sales</dept>
<phone>8723453195</phone>
<email>[email protected]</email>
</person>
</PersonInfo>
<?xml version="1.0"?>
<PersonInfo
xmlns:xsi= "http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation= "personinfo-all.xsd">
<person>
<name>Ram</name>
<title>Executive</title>
<dept>Sales</dept>
<email>[email protected]</email>
<phone>8723453194</phone>
</person>
<person>
<name>Sham</name>
<title>Manager</title>
<dept>Sales</dept>
<phone>8723453195</phone>
<email>[email protected]</email>
</person>
</PersonInfo>
Element Occurrence Indicator – Element Occurrence Indicator – All…All…
<?xml version="1.0"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="PersonInfo">
<xs:complexType>
<xs:sequence>
<xs:element name="person" maxOccurs="unbounded">
<xs:complexType>
<xs:all>
<xs:element name="name" type="xs:string"/>
<xs:element name="title" type="xs:string"/>
<xs:element name="dept" type="xs:string"/>
<xs:element name="email" type="xs:string"/>
<xs:element name="phone" type="xs:string"/>
</xs:all>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element></xs:schema>
<?xml version="1.0"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="PersonInfo">
<xs:complexType>
<xs:sequence>
<xs:element name="person" maxOccurs="unbounded">
<xs:complexType>
<xs:all>
<xs:element name="name" type="xs:string"/>
<xs:element name="title" type="xs:string"/>
<xs:element name="dept" type="xs:string"/>
<xs:element name="email" type="xs:string"/>
<xs:element name="phone" type="xs:string"/>
</xs:all>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element></xs:schema>
Element Occurrence Indicator – Element Occurrence Indicator – ChoiceChoice
<?xml version="1.0"?>
<employees
xmlns:xsi= "http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation= "employee-choice.xsd">
<employee>
<name>Ram</name>
<title>Executive</title>
<salary>20000</salary>
</employee>
<employee>
<name>Sham</name>
<title>Manager</title>
<salary>30000</salary>
</employee>
</employees>
<?xml version="1.0"?>
<employees
xmlns:xsi= "http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation= "employee-choice.xsd">
<employee>
<name>Ram</name>
<title>Executive</title>
<salary>20000</salary>
</employee>
<employee>
<name>Sham</name>
<title>Manager</title>
<salary>30000</salary>
</employee>
</employees>
Element Occurrence Indicator – Choice…Element Occurrence Indicator – Choice…
<?xml version="1.0"?>
<employees
xmlns:xsi= "http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation= "employee-choice.xsd">
<contract>
<name>Anil</name>
<rate>500</rate>
<valid-till>2005-06-30</valid-till>
</contract>
<contract>
<name>Sunil</name>
<rate>500</rate>
<valid-till>2005-07-30</valid-till>
</contract>
</employees>
<?xml version="1.0"?>
<employees
xmlns:xsi= "http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation= "employee-choice.xsd">
<contract>
<name>Anil</name>
<rate>500</rate>
<valid-till>2005-06-30</valid-till>
</contract>
<contract>
<name>Sunil</name>
<rate>500</rate>
<valid-till>2005-07-30</valid-till>
</contract>
</employees>
Element Occurrence Indicator – Choice…Element Occurrence Indicator – Choice…
<?xml version="1.0"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="employees">
<xs:complexType>
<xs:choice>
<xs:element name="employee" type="regularType" maxOccurs="unbounded"/>
<xs:element name="contract" type="contractType" maxOccurs="unbounded"/>
</xs:choice>
</xs:complexType>
</xs:element>
<xs:complexType name="regularType">
<xs:sequence>
<xs:element name="name" type="xs:string"/>
<xs:element name="title" type="xs:string"/>
<xs:element name="salary" type="xs:integer"/>
</xs:sequence>
</xs:complexType>
<xs:complexType name="contractType">
<xs:sequence>
<xs:element name="name" type="xs:string"/>
<xs:element name="rate" type="xs:integer"/>
<xs:element name="valid-till" type="xs:date"/>
</xs:sequence>
</xs:complexType>
</xs:schema>
<?xml version="1.0"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="employees">
<xs:complexType>
<xs:choice>
<xs:element name="employee" type="regularType" maxOccurs="unbounded"/>
<xs:element name="contract" type="contractType" maxOccurs="unbounded"/>
</xs:choice>
</xs:complexType>
</xs:element>
<xs:complexType name="regularType">
<xs:sequence>
<xs:element name="name" type="xs:string"/>
<xs:element name="title" type="xs:string"/>
<xs:element name="salary" type="xs:integer"/>
</xs:sequence>
</xs:complexType>
<xs:complexType name="contractType">
<xs:sequence>
<xs:element name="name" type="xs:string"/>
<xs:element name="rate" type="xs:integer"/>
<xs:element name="valid-till" type="xs:date"/>
</xs:sequence>
</xs:complexType>
</xs:schema>
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