1 / 21

XML Schema

XML Schema. Chao-Hsien Chu, Ph.D. School of Information Sciences and Technology The Pennsylvania State University. XML Declar. Schema Declar. ElementType AttributeType. Purposes of DTD. What elements should be presented? How many of each element were required?

evan
Download Presentation

XML Schema

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 Schema Chao-Hsien Chu, Ph.D. School of Information Sciences and Technology The Pennsylvania State University XML Declar. Schema Declar. ElementType AttributeType

  2. Purposes of DTD • What elements should be presented? • How many of each element were required? • What kind of element content was permitted? • In what order the elements should appear? DTD is the modeling language for XML, which define the structure of a XML document. An DTD file provides the following information:

  3. Components of XML Systems XML Document (Contents) Well-Formed (Syntax) XML Application XML Parser (Processor) XML DTD (Rule) Validate (Structure)

  4. What is XML Schema • DTD is the original modeling language for XML. It has the following deficiencies: - DTD did not follow the regular XML syntax, thus it requires a special parser to validate. - DTD did not support much of data types. - DTD is weak in extensibility. • Schema is the new modeling language for XML,which closely follows XML syntax.

  5. Problems with DTD If the DTD statement for element Quantity is: <!ELEMENT Quantity (#PCDATA)> Then which of the followings syntaxes are valid? <Quantity>5</Quantity> _________ <Quantity>hello</Quantity> _________ <Quantity>5.5</quantity> _________

  6. Facts About XML Schema • Schema documents use XML syntax and are therefore XML documents. • Schemas are XML documents that conform to DTDs, which define the structure of a XML document. • Many organizations and individuals are creating DTDs and schemas for a broad range of categories (e.g., financial transactions, medical prescriptions, etc.). These collections called repositories which are often available free for download from the web.

  7. Why Schema is Better? • XML Schema has Support for Data Types • XML Schemas use XML Syntax • XML Schemas Secure Data Communication • XML Schemas are Extensible • Well-Formed is not Enough

  8. XML Example (1) <?xml version="1.0" encoding="ISO-8859-1"?> <!– Root Element --> <shiporder orderid="889923" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="shiporder.xsd"> <orderperson>John Smith</orderperson> <shipto> <name>Ola Nordmann</name> <address>Langgt 23</address> <city>4000 Stavanger</city> <country>Norway</country> </shipto>

  9. XML Example (2) <item> <title>Empire Burlesque</title> <note>Special Edition</note> <quantity>1</quantity> <price>10.90</price> </item> <item> <title>Hide your heart</title> <quantity>1</quantity> <price>9.90</price> </item> </shiporder>

  10. Components of Schema • XML Declaration • Comments • Schema Declaration • ElementType Declarations • AttributeType Declarations

  11. Example of DTD File (1) <!ELEMENTshiporder (orderperson, shipto, item+)> <!ATTLIST orderid CDATA #REQUIRED> <!ELEMENT orderperson (#PCDATA)> <!ELEMENT shipto (name, address, city, country)> <!ELEMENT name (#PCDATA)> <!ELEMENT address (#PCDATA)> <!ELEMENT city (#PCDATA)> <!ELEMENT country (#PCDATA)> Attribute List Declarations Element Type Declarations

  12. Example of DTD File (1) <!ELEMENT item (title, note?, quantity, price)> <!ELEMENT title (#PCDATA)> <!ELEMENT note (#PCDATA)> <!ELEMENT quantity (#PCDATA)> <!ELEMENT price (#PCDATA)> Element Type Declarations

  13. XML Schema (1) <?xml version="1.0" encoding="ISO-8859-1" ?> <!– Root Element --> <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>

  14. XML Schema (2) <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>

  15. XML Declaration • Is used to provide information regarding processing such as processor (name and version), of the processor Syntax: • <?processor instruction = “value of instruction” ?> Examples: • <?xmlversion = “1.0” ?> • <?xml version="1.0" encoding="Big5" ?> • <?xml version = "1.0" standalone = "no"?>

  16. Comments • A place to write a note for reminding, simple documentation, or commenting out codes for debugging, etc., which will not be seen by the end users. <!-- This is a comment area --> • You can use any character inside the comment area except “--” itself • There is no limitation on the length of the comment area.

  17. Selected XML Schema Data Types • boolean. 0 (false) or 1 (true). • char. A single character. • string. A series of characters. • float. A real number. • int. A whole number. • date. A date formatted as YYYY-MM-DD. • time. A time formatted as HH-MM-SS. • id. Text that uniquely identifies an element or attribute. • idref. A reference to an id. • enumeration. A series of values from which only one may be chosen.

  18. Date and Time Data Types • Name Description • Date Defines a date value • dateTime Defines a date and time value • Duration Defines a time interval • gDay Defines a part of a date - the day (DD) • gMonth Defines a part of a date - the month (MM) • gMonthDay Defines a part of a date - the month and day (MM-DD) • gYear Defines a part of a date - the year (CCYY) • gYearMonth Defines a part of a date - the year and month (CCYY-MM) • Time Defines a time value

  19. Numeric Data Types • Name Description • Byte A signed 8-bit integer • DecimalA decimal value • Int A signed 32-bit integer • Integer An integer value • Long A signed 64-bit integer • negativeInteger An integer containing only negative values ( .., -2, -1.) • nonNegativeInteger An integer containing only non-negative values (0, 1, 2, ..) • nonPositiveInteger An integer containing only non-positive values (.., -2, -1, 0) • positiveIntegerAn integer containing only positive values (1, 2, ..) • Short A signed 16-bit integer • unsignedLong An unsigned 64-bit integer • unsignedInt An unsigned 32-bit integer • unsignedShort An unsigned 16-bit integer • unsignedByte An unsigned 8-bit integer

  20. Advantages of XML Schema • Consistency. It follows XML syntax. • Extensibility. It includes data type and namespaces. • Exchangeability/manipulability. • Rigid specification. • Ease of use. Can use with XML API such as DOM and SAX.

  21. Thank You? Any Question?

More Related