1 / 41

XML Technologies

XML Technologies. X-Schema. 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). What is X-Schema? (2). defines elements that can appear in a document defines attributes that can appear in a document

wesley-bates
Download Presentation

XML Technologies

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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?

More Related