What Is XML Schema

1. general description

2. how to use

save the schema file as *.xsd.

xmlns:xsi=http://www.w3.org/2001/XMLSchema-instance xsi:namespaceSchemaLocation="shiporder.xsd"

3. element classification

Content module in schema

empty: no children elements nor text nodes.

simple: only text nodes are accepted.

complex: only subelements are expected.

mixed: both text nodes and subelements can be present

Type module in schema

simple type: simple content and no attribute

complex type: all other cases

4. simple data type

W3C XML Schema provides an extensive set of predefined datatypes.

Data type						description
xs:string						No white space replacement
	xs:normal izedString					No white space collapsing
		xs:token				White space replacement and collapsing.
			xs:language			accept all the language codes standardized by RFC 1766
			xs:NMTOKEN			a single token (a set of characters without spaces) composed of characters allowed in XML name.
			xs:Name			similar to xs:NMTOKEN with the additional restriction that the values must start with a letter or the characters ":" or "-".
				xs:NCName		without any colons (":")
					xs:ID	must not be any duplicate values in a document.
					xs:IDREF	it must match an ID defined in the same document.
					xs:ENTITY	must match an unparsed entity defined in a DTD.
xs:QName						supports the use of namespace-prefixed names.
xs:anyURI						compensate for the differences of format between XML and URIs
xs:NOTATION						It cannot be used directly in a schema, used through user-defined derived datatypes
xs:hexBinary						code binary content as a character string by translating the value of each binary octet into two hexadecimal digits.
xs:base64binary						maps groups of 6 bits into an array of 64 printable characters

Data type description							description
xs:decimal							represents the decimal numbers.
	xs:integer						don't have any fractional digits in its lexical or value spaces.
		xs:nonPositiveInteger					0 and negative integer
			xs:negativeInteger				Negative integer
		xs:nonNegativeInteger					0 and positive integer
			xs:positiveInteger				Positive interger
			xs:unsignedlong				None signed 64 digits integer
				xs:unsignedInt			None signed 32 digits integer
					xs:unsignedShort		None signed 16 digits integer
						xs:unsignedByte	None signed 8 digits integer
		xs:long					64 digits integer
			xs:int				32 digits integer
				xs:byte			8 digits integer
					xs:short		16 digits integer
xs:double
xs:float
xs:boolean							True or false

Data type	description
xs:dateTime	CCYY-MM-DDThh:mm:ss
xs:date	Gregorian calendar date
xs:gYearMonth	Gregorian calendar month
xs:gYear	Gregorian calendar year.
xs:time	represents a point in time that recurs every day, accepts an optional time zone definition.
xs:gDay	Gregorian calendar day ---DD
xs:gMonth	--MM
xs:gMonthDay	Gregorian calendar month --MM-DD
xs:duration	A period of time PnYnMnDTnHnMnS

List type	description
xs:NMTOKENS	whitespace-separated list of xs:NMTOKEN.
xs:IDREFS	whitespace-separated list of xs:IDREF.
xs:ENTITIES	whitespace-separated list of xs:ENTITY.

5. user defined simpletype

derivation by restriction

A derivation by restriction is done using a xs:restriction element and each facet is defined using a specific element embedded in the xs:restriction element. The datatype on which the restriction is applied is called the base datatype, which can be referenced though a <base> attribute or defined in the xs:restriction element.

<xs:simpleType name="myInteger">

<xs:restriction base="xs:integer">

<xs:minInclusive value="-2"/>

<xs:maxExclusive value="5"/>

</xs:restriction>

</xs:simpleType>

xs:pattern: works on the lexical space; all the other facets constrain the value space.

xs:enumeration: allows definition of a list of possible values.

xs:length: defines a fixed length measured in number of characters (general case) or bytes (xs:hexBinary and xs:base64Binary)

xs:maxLength: defines a maximum length measured in number of characters (general case) or bytes (xs:hexBinary and xs:base64Binary)

xs:minLength: defines a minimum length measured in number of characters (general case) or bytes (hexBinary and base64Binary)

xs:whitespace: defines the way to handle whitespaces. The values of an xs:whiteSpace facet are "preserve" (whitespaces are kept unchanged), "replace" (all the instances of any whitespace are replaced with a space), and "collapse" (leading and trailing whitespaces are removed and all the other sequences of contiguous whitespaces are replaced by a single space).

xs:maxExclusive: defines a maximum value that cannot be reached.

xs:maxInclusive: defines a maximum value that can be reached.

xs:minExclusive: defines a minimum value that cannot be reached

xs:minInclusive: defines a minimum value that can be reached

xs:totalDigits: defines the maximum number of decimal digits.

xs:fractionDigits: specifies the maximum number of decimal digits in the fractional part (after the dot).

derivation by list

use a xs:list element, allows a definition by reference to existing types or embeds a type definition, two definition cannot be mixed.

These facets are xs:length, xs:maxLength, xs:minLength, xs:enumeration and xs:whiteSpace.

<xs:simpleType name="integerList">

<xs:list itemType="xs:integer"/>

</xs:simpleType>

<xs:simpleType name="myIntegerList">

<xs:list>

<xs:simpleType>

<xs:restriction base="xs:integer">

<xs:maxInclusive value="100"/>

</xs:restriction>

</xs:simpleType>

</xs:list>

</xs:simpleType>

derivation by union

using a xs:union element, allowing a definition by reference to existing types or by embedding type definition, Both styles can be mixed

The only two facets that can be applied to a union datatype are xs:pattern and xs:enumeration

<xs:simpleType name="integerOrData">

<xs:union memberTypes="xs:integer xs:date"/>

</xs:simpleType>

<xs:simpleType name="myIntegerUnion">

<xs:union>

<xs:simpleType>

<xs:restriction base="xs:integer"/>

</xs:simpleType>

<xs:simpleType>

<xs:restriction base="xs:NMTOKEN">

<xs:enumeration value="undefined"/>

</xs:restriction>

</xs:simpleType>

</xs:union>

</xs:simpleType>

Complex data type is composed of simple type data type.

6. create a schema

<?xml version="1.0" encoding="ISO-8859-1"?>

<shiporder orderid="889923"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:noNamespaceSchemaLocation="shiporder.xsd">

<orderperson>George Bush</orderperson>

<name>John Adams</name>

<address>Oxford Street</address>

<city>London</city>

</shipto>

<item>

<title>Empire Burlesque</title>

<note>Special Edition</note>

</item>

<item>

<title>Hide your heart</title>

</item>

</shiporder>

Schema for simpleType element

<xs:element name=”” type=””/>

<xs:attribute name=”” type=””/>

Schema for complexType element

define complexType directly

<xs:element name="employee">

<xs:complexType>

<xs:sequence>

<xs:element name="firstname" type="xs:string"/>

<xs:element name="lastname" type="xs:string"/>

</xs:sequence>

</xs:complexType>

</xs:element>

ref to complex data type

<xs:element name="employee" type="personinfo"/>

<xs:complexType name="personinfo">

<xs:sequence>

<xs:element name="firstname" type="xs:string"/>

<xs:element name="lastname" type="xs:string"/>

</xs:sequence>

</xs:complexType>

Empty content

<xs:element name=””>

<xs:complexType>

<xs:attribute name=”” type=””/>

</xs:complexType>

</xs:element>

Simple content

<xs:element name=””>

<xs:complexType>

<xs:simpleContent>

<xs:restriction base=””>

<xs:attribute name=”” type=””/>

</xs:restribution>

</xs:simpleContent>

</xs:complexType>

</xs:element>

Complex content

<xs:element name=””>

<xs:complexType>

<xs:sequence>

<xs:element name=”” type=””/>

</xs:sequence>

<xs:attribute name=”” type=””/>

</xs:complexType>

</xs:element>

Mixed content

<xs:element name=””>

<xs:complexType mixed=”true”>

<xs:sequence>

<xs:element name=”” type=””/>

</xs:sequence>

<xs:attribute name=”” type=””/>

</xs:complexType>

</xs:element>

Global definition

<?xml version="1.0" encoding="ISO-8859-1" ?>

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">

<xs:element name="orderperson" type="xs:string"/>

<xs:element name="name" type="xs:string"/>

<xs:element name="address" type="xs:string"/>

<xs:element name="city" type="xs:string"/>

<xs:element name="country" type="xs:string"/>

<xs:element name="title" type="xs:string"/>

<xs:element name="note" type="xs:string"/>

<xs:element name="quantity" type="xs:positiveInteger"/>

<xs:element name="price" type="xs:decimal"/>

<xs:attribute name="orderid" type="xs:string"/>

<xs:element name="shipto">

<xs:complexType>

<xs:sequence>

<xs:element ref="name"/>

<xs:element ref="address"/>

<xs:element ref="city"/>

<xs:element ref="country"/>

</xs:sequence>

</xs:complexType>

</xs:element>

<xs:element name="item">

<xs:complexType>

<xs:sequence>

<xs:element ref="title"/>

<xs:element ref="note" minOccurs="0"/>

<xs:element ref="quantity"/>

<xs:element ref="price"/>

</xs:sequence>

</xs:complexType>

</xs:element>

<xs:element name="shiporder">

<xs:complexType>

<xs:sequence>

<xs:element ref="orderperson"/>

<xs:element ref="shipto"/>

<xs:element ref="item" maxOccurs="unbounded"/>

</xs:sequence>

<xs:attribute ref="orderid" use="required"/>

</xs:complexType>

</xs:element>

</xs:schema>

Local definition

<?xml version="1.0" encoding="ISO-8859-1" ?>

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">

<xs:element name="shiporder">

<xs:complexType>

<xs:sequence>

<xs:element name="orderperson" type="xs:string"/>

<xs:element name="shipto">

<xs:complexType>

<xs:sequence>

<xs:element name="name" type="xs:string"/>

<xs:element name="address" type="xs:string"/>

<xs:element name="city" type="xs:string"/>

<xs:element name="country" type="xs:string"/>

</xs:sequence>

</xs:complexType>

</xs:element>

<xs:element name="item" maxOccurs="unbounded">

<xs:complexType>

<xs:sequence>

<xs:element name="title" type="xs:string"/>

<xs:element name="note" type="xs:string" minOccurs="0"/>

<xs:element name="quantity" type="xs:positiveInteger"/>

<xs:element name="price" type="xs:decimal"/>

</xs:sequence>

</xs:complexType>

</xs:element>

</xs:sequence>

<xs:attribute name="orderid" type="xs:string" use="required"/>

</xs:complexType>

</xs:element>

</xs:schema>

Named type definition.

<?xml version="1.0" encoding="ISO-8859-1" ?>

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">

<xs:simpleType name="stringtype">

<xs:restriction base="xs:string"/>

</xs:simpleType>

<xs:simpleType name="inttype">

<xs:restriction base="xs:positiveInteger"/>

</xs:simpleType>

<xs:simpleType name="dectype">

<xs:restriction base="xs:decimal"/>

</xs:simpleType>

<xs:simpleType name="orderidtype">

<xs:restriction base="xs:string">

<xs:pattern value="[0-9]{6}"/>

</xs:restriction>

</xs:simpleType>

<xs:complexType name="shiptotype">

<xs:sequence>

<xs:element name="name" type="stringtype"/>

<xs:element name="address" type="stringtype"/>

<xs:element name="city" type="stringtype"/>

<xs:element name="country" type="stringtype"/>

</xs:sequence>

</xs:complexType>

<xs:complexType name="itemtype">

<xs:sequence>

<xs:element name="title" type="stringtype"/>

<xs:element name="note" type="stringtype" minOccurs="0"/>

<xs:element name="quantity" type="inttype"/>

<xs:element name="price" type="dectype"/>

</xs:sequence>

</xs:complexType>

<xs:complexType name="shipordertype">

<xs:sequence>

<xs:element name="orderperson" type="stringtype"/>

<xs:element name="shipto" type="shiptotype"/>

<xs:element name="item" maxOccurs="unbounded" type="itemtype"/>

</xs:sequence>

<xs:attribute name="orderid" type="orderidtype" use="required"/>

</xs:complexType>

<xs:element name="shiporder" type="shipordertype"/>

</xs:schema>

7. others

Indicator

Order：

* All

* Choice

* Sequence

Occurrence：

* maxOccurs

* minOccurs

Group：

* Group

* attributeGroup

Element Substitution

<xs:element name="name" type="xs:string"/>

<xs:element name="navn" substitutionGroup="name"/>

<xs:element name="shipto">

<xs:complexType>

<xs:sequence>

<xs:element ref="name"/>

<xs:element ref="address"/>

<xs:element ref="city"/>

<xs: any type=”xs:string”/>

</xs:sequence>

</xs:complexType>

</xs:element>

<xs:element name=”item” type=”xs:string”/>

<name>xxxxx</name>

</shipperto>