04-XML Schema - Compatibility Modesclab.konkuk.ac.kr/attachments/lecture/4/04-XML_Schema.pdf · 2019-09-23 · Namespace in XML Schema qTarget Namespace ØUsing XML Schema, we can

Instructor: Prof. Young-guk HaDept. of Computer Science & Engineering

웹 기술 및 응용

XML Schema

2019년 2학기

2웹기술응용설계

Outline

q History

q Comparison with DTD

q Syntax

Ø Definitions and declaration

Ø Simple types

Ø Namespace

Ø Complex types

Ø Content models

Ø Secondary components


Birth of XML Schema

q XML-Data: Jan 1998

Ø Basic concepts of XML Schema

Ø For W3C internal discussion only

q XDR (XML-Data Reduced): Jul 1998

Ø Refines and subsets XML-Data down to manageable size

q Other Schema Languages

Ø DCD for XML (Document Content Description)

Ø DDML (Document Definition Markup Language)

Ø SOX (Schema for Object-oriented XML)

q XML Schema (W3C Recommendation)

Ø May 2001: XML Schema 1.0

Ø Oct. 2004: XML Schema 1.0 2nd Edition

Ø Apr. 2012: XML Schema 1.1

v XML Schema is also called XML Schema Definition Language (XSD)

v W3C XSD Recommendation- Part 0: Primer- Part 1: Structures- Part 2: Data types


Outline

q History


q Syntax


Ø Simple types

Ø Namespace

Ø Complex types

Ø Content models



DTD vs. XML Schema


Outline

q History


q Syntax


o Building blocks

o Element & attribute declaration

Ø Simple types

Ø Namespace

Ø Complex types

Ø Content models



Building Blocks

q Schema declaration

Ø Root of the document

Ø Namespace declarations

q Declarations

Ø Elements

Ø Attributes

q Type definitions

Ø Simple typesfor elements and attributes

Ø Complex typesfor elements


q Element declaration

Declarations

<product><name>Bolt-001</name><amount>1000</amount>

</product>

<product><name>Bolt-002</name>

</product>

<product><name>Bolt-003</name><amount>1000</amount><amount>2000</amount><amount>3000</amount>

</product>

Example) XML document with element amount

à DTD

decimal

• type := simpleType | complexType• Cardinality constraints

- minOccurs := 0, 1, 2, …- maxOccurs := 0 ~ unbounded


q Cardinality constraints

Declarations (cont’d)

XML Schema DTD

minOccurece = 1maxOccurence = 1 e

minOccurece = 0maxOccurence = 1 e?

minOccurece = 1maxOccurence = unbounded e+

minOccurece = 0maxOccurence = unbounded e*

minOccurece = nmaxOccurence = m N/A


q Attribute declaration

Declarations (cont’d)

à DTD#REQUIRED >

<quantity partNum=“Bolt-001” unit=“ea” value=“1000”/>

<quantity unit=“ea” value=“2000” partNum=“Bolt-002”/>

<quantity unit=“ea” value=“3000”/> à invalid

Example) XML document with attribute partNum

• type := simpleType• use := required |

optional |prohibited


Outline

q History


q SyntaxØ Definitions and declaration

Ø Simple types

o Built-in, user-derived types

o List, union types

o Facets

Ø Namespace

Ø Complex types

Ø Content models



XML Schema Datatype Hierarchy

DTD 호환성

user-defined simple types

user-defined simple types derived by list, union or restriction


Simple Types

q Built-in typesØ Derived from anySimpleType

o Primitive types

• Types in their own right

• Atomic: not defined in terms of other data-types

o Derived types

• List or restriction of existing primitive types

q User-defined types

Ø Defined by the author of the schema and particular to the schema

o List, union or restriction is allowed for user-defined simple types

o Extension is NOT allowed for simple typesv Note that complex types can be derived by either extension or restriction


Simple Types: Primitive Types

double


Simple Types: Derived Types

-128~127


Simple Types: User-Defined Types

q Derived by restriction

Ø Users can derive a simple type by restriction of another

simple base type

o Extension is NOT allowed

o I.e., expansion of range or addition of attributes is not

allowed

E.g.) Defining myInteger of range 1000~9999


Facets (1/2)

q lengthØ Determines the length of data type

o For string, it means the number of characters it contains

o For binary data such as base64Binary, it means the number of octets

q minLength

Ø Sets the minimum length of the data type

Ø Less than or equal to maxLength

q maxLengthØ Sets the maximum length of the data type

q patternØ Specifies a regular expression which the element content should match

q enumeration

Ø Contains a set of values that element should choose


Facets (2/2)

q whiteSpaceØ Controls how the processor should treat whitespace chars

o preserve (default), replace, or collapse

q maxInclusive, maxExclusiveØ Sets an upper bound for values using the data type

q minInclusive, minExclusiveØ Sets a lower bound for values using the data type

v minInclusive ≤ value ≤ maxInclusivev minExclusive < value < maxExclusive

q precision, scaleØ precision determines the maximum number of digits the data

type may have (including comma ‘.’)

Ø scale sets the maximum number of digits appearing in the

fractional part of a decimal based data type


Facets Examples

/> à 10 chars long, e.g., “123-456-78”

e.g., 1234.5 , 3425.1, 9182.5, …

e.g., one of “10”, “20”, or “part Code”

à e.g., “123-AB”, “327-XY”, “617-ST”, …

scale value=“1”/> precision value=“6”/>


Simple Types: List types

q List types

Ø Derived from existing primitive types, NOT another list or

complex type

Ø Built-in: NMTOKENS, IDREFS, ENTITIES

Ø Using whitespace as a delimiter

E.g.) User-defined list type

<element name=“listOfInteger” type=“listOfIntegerType”>

XML Schema of listOfIntegerType XML Document


Simple Types: Union types

q Union types

Ø Enables an element or attribute value to be one or more

instances of one type drawn from the union of multiple

primitive and list types

E.g.) <element name=“zips” type=“zipUnion”>

XML Schema of zipUnion type XML Document


Outline

q History


q Syntax


Ø Simple types

Ø Namespace

Ø Complex types

Ø Content models



Namespace

q XML NamespaceØ W3C Recommendation

o First edition on Jan. 1999

o Currently, v1.0 3rd Ed. (Dec. 2009) and v1.1 2nd Ed. (Aug. 2006)

Ø Resolves name conflict between elements or attributes in XML documents

o Qualified names of elements or attributes are required to be globally uniqueand persistent

o Namespace can be used in XML docs and XSD docs as well

Ø Identified by URI (URL or URN, commonly URL)o However, URI is quite long, so a short prefix is used instead

o In case of using URL, it needs NOT to point to actual documents or locations

Ø Default namespaceo Unprefixed elements or attributes are associated with the default namespace of

themselves or parent element’s (block scope)* URL: Uniform Resource Locator (e.g., http://www.w3.org/2001/XMLSchema)* URN: Uniform Resource Name (e.g., urn:isbn:0451450523)* URI: Uniform Resource Identifier (= URL + URN)


Namespace (cont’d)

ü 세 개의 <title> element가

서로 다른 의미로 사용되고 있음(또한 같은 scope 내에 동음이의element가 사용될 수도 있음)

ü 또한 타 Markup 언어의 <title> element와도 구별할 필요가 있음(예: XHTML의 <title>)

ü 각각의 <title> element가

parser에 의해 식별되지 않는다면well-formed이지만 valid하지 않은XML 문서로 해석될 가능성이 있음


q Namespace declaration

q Default namespace declaration

q Target namespace declaration (used in XSD docs only)


<element_name xmlns:edi=“http://ecommerce.org/schema”>

Prefix Namespace URI

<element_name xmlns=“http://ecommerce.org/schema”>

E.g.) <schema xmlns=“http://www.w3.org/2001/XMLSchema” ...>

<schema targetNamespace=“http://ecommerce.org/schema”>

* No prefix is defined for default namespace



q 네임스페이스 사용 예

Ø Namespace prefix = edi

Ø Namespace URI = “http://ecommerce.org/schema”

<edi:x xmlns:edi=“http://ecommerce.org/schema”><edi:price edi:units=“Euro”>32.18</edi:/price>

</edi:x>

q 디폴트 네임스페이스를 사용하는 경우

<x xmlns=“http://ecommerce.org/schema”><price unit=“Euro”>32.18</price>

</x>



q Well-known namespaces

Ø xsd=“http://www.w3.org/2001/XMLSchema”

Ø xsi=“http://www.w3.org/2001/XMLSchema-instance”

Ø xhtml=“http://www.w3.org/1999/xhtml”

Ø xsl=“http://www.w3.org/1999/XSL/Transform”

Ø wsdl=“http://www.w3.org/ns/wsdl”

Ø soapenv=“http://www.w3.org/2003/05/soap-envelope”

Ø soaprpc=“http://www.w3.org/2003/05/soap-rpc”

Ø xmldsig=“http://www.w3.org/2000/09/xmldsig”

Ø xmlenc=“http://www.w3.org/2001/04/xmlenc”

Ø …



q 네임스페이스의 적용 범위

Ø XML 문서는 하나 이상의 네임스페이스를 가질 수 있음

Ø 네임스페이스는 네임스페이스가 선언된 element와 그 element의 내

부에 nested된 모든 element 및 attribute들에 적용됨 (block scope)


Namespace in XML Schema

q Target NamespaceØ Using XML Schema, we can

create new elements and

attributes, and keep them in a

specific namespace

Ø This specific namespace is

target namespace where the

newly created elements and

attributes will reside

Ø During validation, an XML

parser verifies whether the

elements and attributes used

in the document exist in the

declared target namespace/


<schema xmlns="http://www.w3.org/2001/XMLSchema"xmlns:po="http://www.example.com/PO"targetNamespace="http://www.example.com/PO">

<complexType name="USAddress"><sequence>

<element name="name" type="string"/><element name="street" type="string"/>

</sequence></complexType><complexType name="PurchaseOrderType">

<sequence><element name="shipTo" type="po:USAddress"/><element name="billTo" type="po:USAddress"/>

</sequence></complexType>

...<element name="purchaseOrder" type="po:PurchaseOrderType"/>

</schema>

Namespace in XML Schema (cont’d)


<purchaseOrder xmlns=“http://www.example.com/PO” ... >

<shipTo><name>Micheal</name><street>Main street</street>

</shipTo>

<billTo><name>Tom</name><street>Fremont street</street>

</billTo>

...

</purchaseOrder>


q Valid XML document example

à targetNamespace of the schema document


q Including schema definitions from another external documents


<schema xmlns="http://www.w3.org/2001/XMLSchema"xmlns:po="http://www.example.com/PO"targetNamespace="http://www.example.com/PO"… >

<include schemaLocation=“http://www.example.com/PO2.xsd”><element name="purchaseOrder" type="po:PurchaseOrderType"/>

…</schema>

<schema xmlns="http://www.w3.org/2001/XMLSchema"targetNamespace="http://www.example.com/PO"… >

<complexType name="PurchaseOrderType">…

</complexType></schema>

http://www.example.com/PO1.xsd

http://www.example.com/PO2.xsd

* 반드시 동일한target namespace


Outline

q History



Ø Simple types

Ø Namespace

Ø Complex types

o Extension, restriction

o Adding attribute

o Global & local element

Ø Content models



Complex Types

q Features of complex types

Ø Carrying attributes and elements

o I.e., contains other types (simple or complex)

Ø Can be derived by both restriction and extension

o Cf., only restriction allowed for simple types

Ø Various and flexible content models

o Any, empty, element-only, mixed

o Model groups: sequence, all, choice

o Cardinality constraints: minOccurs, maxOccurs

o Combinations of the above


Complex Types: Complex Type Definition

<schema xmlns="http://www.w3.org/2001/XMLSchema"xmlns:po="http://www.example.com/PO"targetNamespace="http://www.example.com/PO">

<element name="purchaseOrder" type="po:PurchaseOrderType"/>

<complexType name="PurchaseOrderType">

<sequence><element name="shipTo" type="po:USAddress"/><element name="billTo" type="po:USAddress"/><element ref="po:comment"

minOccurs="0“ maxOccurs=“10”/>

</sequence><attribute name="orderDate" type="date"/>

</complexType>

<complexType name="USAddress"><sequence>

<element name="name" type="string"/><element name="street" type="string"/>

</sequence></complexType>… …

Attributes

Elements(simple or

complex types)

Specificcardinality

Model group(can be nested)


Complex Types: Attribute Declaration

q Only simple types can be used for attribute types

Ø Examples

<attribute name=“orderDate”/>

<attribute name=“orderDate” type=“date”/>

<attribute name=“orderDate” type=“date”

use=“required” fixed=“2003-09-19”/>

<attribute name=“orderDate” type=“date”

use=“optional” default=“2003-09-19”/>

<attribute name=“orderDate” type=“date”use=“prohibited”/>

* prohibited: usually used to restrict the base element


Complex Types: Extension & Restriction (1)

q Deriving types by extension

Ø Base type ⊆ Derived type

Ø Extension from a complex type

o Adding new elements or attributes to a base type

Ø Extension from a simple type

o Adding new attributes to a base type

o Expanding range, length, …

q Deriving types by restriction

Ø Base type ⊇ Derived type

Ø Restriction from a complex type

o Limited cardinality of element, use of attributes, …

o Prohibiting attributes(e.g., use=“prohibited”)

Ø Restriction from a simple type

o Limiting range, length, …

[ Derivation of Complex Types ]

<complexType>

<complexContent> <simpleContent>

<restriction> <extension> <restriction> <extension>


Complex Types: Extension & Restriction (2)

[ Extension from a simple typeby adding an attribute ]

[ Extension and restriction from a complex type ]

Additionalelements

à Limited cardinality


Complex Types: Scope of Elements

q Global elements

Ø Direct children of the

“schema” element

Ø Can be referenced using

attribute “ref”

q Local elements

Ø Child elements of another

element

Ø Local elements with the

same name can be

declared in different

scopes Global Element Local Element


Outline

q History



Ø Simple types

Ø Namespace

Ø Complex types

Ø Content modelso Any, empty, mixed

o Sequence, choice, all

o minOccurs, maxOccurs



Basic Content Models

q Any typeØ Default content model when you declare an element in XML

Schemao <element name=“anything”/>

== <element name=“anything” type=“anyType”/>

Ø Can contain any contents (completely unconstrained)o E.g., string, integer, elements, …, or mixture of them

q Empty contentØ Can carry attributes, but prevent any content appearing as text or

child elementso <element name=“empty” xsi:nil=“true”/>

v xmlns:xsi=“http://www.w3.org/2001/XMLSchema-instance”

q Mixed content and element onlyØ Mixture of text contents and elements

o <xsd:element name="letterBody"><xsd:complexType mixed="true"> ...

v Default: mixed=“false” (element-only)


Mixed Content Model

[ XML Schema ]

[ Valid XML Document ]


Model Groups

q sequence group

Ø Only allows the specified order in an instance

q choice group

Ø Allows only one of its children to appear in an instance

q all group

Ø Unordered subset of individual elements

o Children may appear in any order

o Children may appear once or not (no more than once)

o Children must all be individual elements (no groups)

o Children are restricted to contain local elements or refs to top-level elements declarations only

Ø Must appear

o as the sole child

o at the top of content model


Cardinality Constraints

q minOccursØ Value: nonnegative integer (Default = 1)

q maxOccursØ Value: nonnegative integer or “unbounded” (Default = 1)

q Examples<element name=“e1” /> ==<element name=“e1” minOccurs=“1” maxOccurs=“1”/>

à DTD: <!ELEMENT e0 (e1)>

<element name=“e1” minOccurs=“0” maxOccurs=“1”/>à DTD: <!ELEMENT e0 (e1?)>

<element name=“e1” minOccurs=“0” maxOccurs=“unbounded”/>à DTD: <!ELEMENT e0 (e1*)>

<element name=“e1” minOccurs=“1” maxOccurs=“unbounded”/>à DTD: <!ELEMENT e0 (e1+)>

<element name=“e1” minOccurs=“3” maxOccurs=“10”/>

à can not be described with DTD


Content Model Example: Sequence & Choice

<xsd:complexType name="PurchaseOrderType">

<xsd:sequence>

<xsd:choice>

<xsd:sequence>

<xsd:element name="shipTo" type="USAddress"/>

<xsd:element name="billTo" type="USAddress"/>

</xsd:sequence>

<xsd:element name="singleUSAddress" type="USAddress"/>

</xsd:choice>

<xsd:element ref="comment" minOccurs="0"/>

<xsd:element name="items" type="Items"/>

</xsd:sequence>

<xsd:attribute name="orderDate" type="xsd:date"/>

</xsd:complexType>


Content Model Example: Sequence & Choice

<PurchaseOrder orderDate=“2012-03-29”>

<shipTo> ... </shipTo><billTo> ... </billTo><comment> ... </comment><items> ... </items>

</PurchaseOrder>


<singleUSAddress> ... </singleUSAddress><comment> ... </comment><items> ... </items>

</PurchaseOrder>


<singleUSAddress> ... </singleUSAddress><items> ... </items>

</PurchaseOrder>

[ Valid XML documents ]


Content Model Example: All

<xsd:complexType name="PurchaseOrderType"><xsd:all><xsd:element name="shipTo" type="USAddress"/><xsd:element name="billTo" type="USAddress"/><xsd:element ref="comment" minOccurs="0"/><xsd:element name="items" type="Items"/>

</xsd:all><xsd:attribute name="orderDate" type="xsd:date"/>

</xsd:complexType>

<xsd:complexType name="PurchaseOrderType"><xsd:sequence><xsd:all><xsd:element name="shipTo" type="USAddress"/><xsd:element name="billTo" type="USAddress"/><xsd:element name="items" type="Items"/>

</xsd:all><xsd:sequence><xsd:element ref="comment" minOccurs="0" maxOccurs="unbounded"/>

</xsd:sequence></xsd:sequence><xsd:attribute name="orderDate" type="xsd:date"/>

</xsd:complexType>

*** Illegal: used in a sequence group ***


Outline

q History



Ø Simple types

Ø Namespace

Ø Complex types

Ø Content models

Ø Secondary componentso Attribute groups

o Annotation

o Redefinition

o Abstract element

o Null element


Attribute Groups & Annotation

q Attribute groups

Ø Improves readability of

schemas and facilitates

updating schemas

Ø Must appear at the end of

complex type definitions

q Annotation

Ø Annotating schemas for

benefit of human readers

and applications as well

Ø Use “xml:lang” attribute to

indicate the language of the

information

<attributeGroup name="myAttrGroup"><attribute . . . />. . .

</attributeGroup>

<complexType name="myelement">. . .

<attributeGroup ref="myAttrGroup"/></complexType>

<annotation><documentation xml:lang=“en”>

… Some documentation …</documentation>

</annotation>


Redefinition

q To provide some support for evolution or versioningof XML schema files

Ø The redefine mechanism enables you to redefine simple

and complex types, groups, and attribute groups that are

obtained from external schema files (i.e., restriction or

extension from the original version)

o Cf., the include mechanism enables you to use externally

created schema components “as-is” (i.e., without any

modification)

Ø Redefinition requires the external components to be in the

same target namespace as the redefined schema


Redefinition Example

… targetNamespace="http://mycom.com/IPO" …

<complexType name="personName"><sequence>

<element name="title" minOccurs="0"/><element name="forename" minOccurs="0“ maxOccurs="unbounded"/>


… targetNamespace="http://mycom.com/IPO” xmlns:p="http://mycom.com/IPO" …

<redefine schemaLocation=“v1.xsd"><complexType name="personName">

<complexContent><extension base=“p:personName">

<sequence><element name="generation" minOccurs="0"/>

</sequence></extension>

</complexContent></complexType>

</redefine>

<element name="author" type="personName"/>

v1.xsd :

v2.xsd :


Substitution Groups

q Substitution groups allow elements to be substituted for other elements

Ø Head element

o a particular named element to be substituted

o E.g., ipo:comment

Ø Substitutableelements

o E.g., shipComment, customerComment

v Both types of elements must be declared as

global elements

<element name="ipo:comment" type="string"/><element name="shipComment" type="string"

substitutionGroup="ipo:comment"/><element name="customerComment" type="string"

substitutionGroup="ipo:comment"/>

<element name="item" minOccurs="0" maxOccurs="unbounded"><complexType>

<sequence><element name="productName" type="string"/><element ref="ipo:comment" maxOccurs=“unbounded"/><element name="shipDate" type="date" minOccurs="0"/>


</element>

<item partNum="833-AA"><productName>Lapis necklace</productName><ipo:comment>Order #1</ipo:comment><ipo:shipComment>Use gold wrap</ipo:shipComment><ipo:customerComment>Want ASAP!</ipo:customerComment><shipDate>1999-12-05</shipDate>

</item>


Abstract Elements and Abstract Types

q Abstract elements can NOT

be used in an instance

document

Ø To make a substitutable

element MUST appear in

the instance document

o From the previous example

<element name=“ipo:comment" type="string” abstract="true"/>

q Abstract type elements

Ø Must be used with a

specific derived type in

instance documents

o E.g., <transport> element

<complexType name="Vehicle" abstract="true"/>

<complexType name="Car"> <complexContent>

<extension base="ns:Vehicle"/></complexContent>

</complexType>

<complexType name="Plane"> <complexContent>

<extension base="ns:Vehicle"/></complexContent>

</complexType>

<element name="transport" type="ns:Vehicle"/>

<transport/> à Schema invalid

<transport xsi:type="ns:Car"/> à Schema valid

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


Null Element

q An element that can has a null value as its content

Ø Meaning of null value

o Unknown

o Not applicable

o The element may be absent

Ø XML has no actual null value that appears as element

contento E.g.) <shipDate>null</shipDate> à “null” string value

q Using attribute “xsi:nil”Ø In the schema: nillable=“true”Ø In the document: xsi:nil=“true”

/>


References

q XML Schema 1.0 (2nd Ed) Part 0: Primer

Ø http://www.w3.org/TR/xmlschema-0/

q XML Schema 1.0 (2nd Ed) Part 1: Structures


q XML Schema 1.0 (2nd Ed) Part 2: Data types


q Namespaces 1.0 (3rd Ed) in XML

Ø http://www.w3.org/TR/xml-names/

http://www.w3.org/TR/xmlschema-0/



http://www.w3.org/TR/xml-names/

04-XML Schema - Compatibility Modesclab.konkuk.ac.kr/attachments/lecture/4/04-XML_Schema.pdf · 2019-09-23 · Namespace in XML Schema qTarget Namespace ØUsing XML Schema, we can

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