1. XML Technologies X-Schema

2. What is X-Schema? (1) • XML-based alternative to DTD • Describes the structure of an XML document • Also referred to as XML Schema Definition (XSD)

3. What is X-Schema? (2) • defines elements that can appear in a document • defines attributes that can appear in a document • defines which elements are child elements • defines the order of child elements • 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 and fixed values for elements and attributes

4. X-Schema vrs DTD • XML Schemas are extensible to future additions • XML Schemas are richer and more powerful than DTDs • XML Schemas are written in XML • XML Schemas support data types • XML Schemas support namespaces

5. X-Schema makes it easy to • describe allowable document content • validate the correctness of data • work with data from a database • define restrictions on data • define data formats • convert data between different data types

6. Why is it better to use an XML based schema? • We know the language • Can be edited with XML editors • Can be parsed with XML parsers • Can be manipulated with XML DOM • Can be transformed with XSLT

7. Benefits of X-Schemas • Ensure secure data communication • 3/11/2004 is the 3rd of November or the 11th of March? • Can reuse schemas • Use one or many in the same document • Create own data types

8. How to use X-Schema <?xml version="1.0"?> <note xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="note.xsd"> <to>Tove</to> <from>Jani</from> <heading>Reminder</heading> <body>Don't forget me this weekend!</body> </note>

9. The actual schema <?xml version="1.0"?> <xs:schema> <xs:element name="note"> <xs:complexType> <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:element> </xs:schema>

10. <schema> element • Root element of any schema • May contain attributes • xmlns:xs="http://www.w3.org/2001/XMLSchema" • Indicate the XSchema namespace • targetNamespace="http://www.um.edu.mt" • Indicate that the elements defined (to, from, etc) come from the above namespace • xmlns="http://www.um.edu.mt" • Sets the default namespace • elementFormDefault="qualified“ • Qualified = all elements can be validated • Unqualified = only root element can be validated with the namespace

11. Elements • A simple element contains only text • But it can have different types or restrictions (facets) • <xs:element name="xxx" type="yyy"/> • <xs:element name=“age" type=“xs:integer"/>

12. Element Built-In Types • xs:string • xs:decimal • xs:integer • xs:boolean • xs:date • xs:time

13. Default and Fixed types <xs:element name="color" type="xs:string" default="red"/> <xs:element name="color" type="xs:string" fixed="red"/>

14. Attributes • Simple elements cannot have attributes • Only complex elements have attributes • An attribute is declared as a simple type <xs:attribute name="xxx" type="yyy"/>

15. Default, Fixed and Optional attributes <xs:attribute name="lang" type="xs:string" default="EN"/> <xs:attribute name="lang" type="xs:string" fixed="EN"/> <xs:attribute name="lang" type="xs:string" use="required"/> * Optional by default (unless specified)

16. Restrictions (Facets) - Range <xs:element name="age"> <xs:simpleType> <xs:restriction base="xs:integer"> <xs:minInclusive value="0"/> <xs:maxInclusive value="120"/> </xs:restriction> </xs:simpleType> </xs:element>

17. Restrictions (Facets) – Set 1 <xs:element name="car"> <xs:simpleType> <xs:restriction base="xs:string"> <xs:enumeration value="Audi"/> <xs:enumeration value="Golf"/> <xs:enumeration value="BMW"/> </xs:restriction> </xs:simpleType> </xs:element>

18. Restrictions (Facets) – Set 2 <xs:element name="car" type="cType"/> <xs:simpleType name="cType"> <xs:restriction base="xs:string"> <xs:enumeration value="Audi"/> <xs:enumeration value="Golf"/> <xs:enumeration value="BMW"/> </xs:restriction> </xs:simpleType>

19. Restrictions (Facets) - Pattern <xs:element name="letter"> <xs:simpleType> <xs:restriction base="xs:string"> <xs:pattern value="[a-z]"/> </xs:restriction> </xs:simpleType> </xs:element>

20. Restrictions (Facets) - Patterns Regular expressions example [A-Z] any letter uppercase [A-Z][A-Z] two letters uppercase [a-zA-Z] any letter any case [xyz] x or y or z [0-9] any number one digit ([A-Z])+ one or more ([A-Z])* zero or more male|female either or [a-zA-Z]{8} exactly 8 characters

21. Restricting white space (1) <xs:element name="address"> <xs:simpleType> <xs:restriction base="xs:string"> <xs:whiteSpace value="preserve"/> </xs:restriction> </xs:simpleType> </xs:element>

22. Restricting white space (2) • Value can be • Preserve • Do not remove white space • Replace • Replace line feeds, tabs, spaces, and carriage returns with spaces • Collapse • Same as replace but collapse multiple spaces into one

23. Restrictions (Facets) - Length <xs:element name="password"> <xs:simpleType> <xs:restriction base="xs:string"> <xs:minLength value="5"/> <xs:maxLength value="8"/> </xs:restriction> </xs:simpleType> </xs:element>

24. Summarising Restrictions

25. Complex Elements • empty elements • elements that contain only other elements • elements that contain only text • elements that contain both other elements and text

26. Complex Empty Elements <xs:element name="product"> <xs:complexType> <xs:attribute name="prodid" type="xs:positiveInteger"/> </xs:complexType> </xs:element> Ex <product prodid="1345" />

27. Complex Elements Only • Contains only other elements <xs:element name="person"> <xs:complexType> <xs:sequence> <xs:element name="firstname" type="xs:string"/> <xs:element name="lastname" type="xs:string"/> </xs:sequence> </xs:complexType> </xs:element>

28. Complex Elements Only Ex <person> <firstname>John</firstname> <lastname>Smith</lastname> </person>

29. Complex TextOnly Element <xs:element name="shoesize"> <xs:complexType> <xs:simpleContent> <xs:extension base="xs:integer"> <xs:attribute name="country" type="xs:string" /> </xs:extension> </xs:simpleContent> </xs:complexType> </xs:element> Eg <shoesize country="france">35</shoesize>

30. Complex Mixed Content <xs:element name="letter"> <xs:complexType mixed="true"> <xs:sequence> <xs:element name="name" type="xs:string"/> <xs:element name="orderid" type="xs:positiveInteger"/> <xs:element name="shipdate" type="xs:date"/> </xs:sequence> </xs:complexType> </xs:element>

31. 7 Indicators • Order indicators: • All • All must occur but in any order • Choice • Either or can occur • Sequence • Must appear in a specified sequence • Occurrence indicators: • maxOccurs • minOccurs • Group indicators: Group elements or attributes together and allow for reuse • Group name • attributeGroup name

32. All, Choice, Sequence indicator <xs:element name="person"> <xs:complexType> <xs:all> <xs:element name="firstname" type="xs:string"/> <xs:element name="lastname" type="xs:string"/> </xs:all> </xs:complexType> </xs:element>

33. Occurrence indicator <xs:element name="person"> <xs:complexType> <xs:sequence> <xs:element name="child_name" type="xs:string" maxOccurs="10" minOccurs="0"/> </xs:sequence> </xs:complexType> </xs:element>

34. <any> and <anyAttribute> <xs:element name="person"> <xs:complexType> <xs:sequence> <xs:element name="child_name" type="xs:string" maxOccurs="10" minOccurs="0"/> <xs:any minOccurs="0"/> </xs:sequence> <xs:anyAttribute/> </xs:complexType> </xs:element> *allows for any element or attribute but it has to be defined just the same in another XSchema

35. Substitutions <xs:element name="name" type="xs:string"/> <xs:element name=“isem" substitutionGroup="name"/> Allows for … <customer> <isem>John</isem> </customer>

36. String Datatype

37. Date Datatype

38. Numeric Datatype

39. Example

40. Exercise • Define an XML Vocabulary for a Toaster Markup Language (TML) using XSchema • It must support features such as: • Print message on toast • Display on LCD • Time stamp

41. Questions?