S

XMLDTD and XML

SchemaDiscussion Sessions 1A and 1B

Session 2

XMLeXtensible Markup Language

<?xml version="1.0" encoding="UTF-8"?><wonders><!-- Wonders of the ancient world --> <wonder> <name>Colossus of Rhodes</name> <location>Greece</location> <height units="feet">107</height> </wonder> <wonder> <name>Great Pyramid of Giza</name> <location>Egypt</location> <height units="meters">147</height> </wonder></wonders>

DTDDocument Type Definition

<?xml version="1.0" encoding="UTF-8"?><!ELEMENT Bookstore ( Book* ) >

<!ELEMENT Book ( Title, Author+, Remark? ) ><!ATTLIST Book ISBN CDATA #REQUIRED Price CDATA #REQUIRED Edition CDATA #IMPLIED >

<!ELEMENT Title ( #PCDATA ) ><!ELEMENT Author ( #PCDATA | ( FirstName, LastName ) ) ><!ELEMENT FirstName ( #PCDATA ) ><!ELEMENT LastName ( #PCDATA ) ><!ELEMENT Remark ( #PCDATA ) >

Meaning of *, +, and ?

#PCDATA and CDATA

Order of elements and attributes

#REQUIRED and #IMPLIED

DTDDocument Type Definition

What about an empty element?

Can we define an unsorted list of elements?

An element with anything?

Attributes with choices?

Why to use attribute IDs?

IDREF(S)?

<!ELEMENT Image EMPTY >

<!ELEMENT Author ( #PCDATA | FullName | NickName )* >

<!ELEMENT Remark ANY >

<!ATTLIST Book Language ( EN | ES ) #REQUIRED >

<!ATTLIST Book ISBN ID #REQUIRED >

<!ATTLIST BookCollection ISBNRefs IDREFS #REQUIRED >

DTDDocument Type Definition

Pros Compact structure Can be defined

inline Wide support

among parsers

Cons Are not written in

XML Don’t support

Namespaces Don’t have data –

typing Have limited

capacity for counters

XML Schema

Types of elements

Simple type

Complex type

Text only

Elements onlyElements and

textText only

Empty

+

Att

ribute

s

XML SchemaSimple Type

<location>Egypt</location>

Different ways to define this element:

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

<xs:element name="location" type="stringType" />...<xs:simpleType name="stringType"> <xs:restriction base="xs:string"> <xs:maxLength value="256" /> </xs:restriction></xs:simpleType>

XML SchemaComplex Type

Complex type

Text + Attributes

Elements + AttributesAttributes onlyText + Elements + Attributes

Simple content

Complex content

XML SchemaComplex Type: Simple Content

<xs:element name="yearBuilt"> <xs:complexType> <!-- An anonymous type --> <xs:simpleContent> <xs:extension base="xs:positiveInteger"> <!-- Inheritance --> <xs:attribute name="era"> <xs:simpleType> <xs:restriction base="xs:string"> <!-- Regular expression --> <xs:pattern value="(BC)|(AD)” /> </xs:restriction> </xs:simpleType> </xs:attribute> </xs:extension> </xs:simpleContent> </xs:complexType></xs:element>

<yearBuilt era="BC">100</yearBuilt>

Just to generate this simple line!

XML SchemaComplex Type: Complex Content 1

<xs:element name="ancient_wonders"> <xs:complexType> <xs:complexContent> <xs:restriction base="xs:anyType”> <xs:sequence> <xs:element name="wonder" type="wonderType" minOccurs="2" maxOccurs="unbounded"/> </xs:restriction> </xs:complexContent> </xs:sequence> </xs:complexType></xs:element>

What does this segment of code do?

XML SchemaComplex Type: Complex Content 2

<xs:element name="image"> <xs:complexType> <xs:attribute name="source" default="ancient.jpg" type="xs:string"/> </xs:complexType></xs:element>

An empty element that contains only attributes

XML SchemaComplex Type: Complex Content 3

<xs:element name="story" minOccurs="0"> <xs:complexType mixed="true"> <xs:sequence> <xs:element name="para" minOccurs="0" maxOccurs="unbounded"> <xs:complexType /> <!-- Completely empty element --> </xs:element> </xs:sequence> <xs:attribute name="language" use="optional" type="xs:string" /> </xs:complexType></xs:element>

A mixed element that combines children elements, text, and attributes