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uptu web technology unit 2 Xml2

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Abhishek Kesharwani

This document provides an introduction to XML Schema, including: - XML Schema defines the structure and legal elements of an XML document, similar to a DTD. - XML Schema supports data types, which makes validating data easier. - XML Schemas are written in XML syntax, allowing them to be edited, parsed, and manipulated using XML tools. - XML Schemas help secure data communication by ensuring mutual understanding of data formats. - XML Schemas are extensible and can reference other schemas. - Examples are provided of a simple XML document and its corresponding XML Schema.

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Web Technology (NCS-504) Prepared By Mr.Abhishek Kesharwani Assistant Professor,UCER Naini,Allahabad
XML Schema
Introduction to XML Schema XML Schema is an XML-based alternative to DTD. An XML schema describes the structure of an XML document. The XML Schema language is also referred to as XML Schema Definition (XSD). 3
Purpose of an XML Schema The purpose of an XML Schema is to define the legal building blocks of an XML document, just like a DTD. 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
XML Schemas Support Data Types One of the greatest strength of XML Schemas is the support for data types. With support for data types: It is easier to describe allowable document content It is easier to validate the correctness of data It is easier to work with data from a database It is easier to define data facets (restrictions on data) It is easier to define data patterns (data formats) It is easier to convert data between different data types 5
XML Schemas use XML Syntax Another great strength about XML Schemas is that they are written in XML.Some benefits of that XML Schemas are written in XML: You don't have to learn a new language You can use your XML editor to edit your Schema files You can use your XML parser to parse your Schema files You can manipulate your Schema with the XML DOM You can transform your Schema with XSLT 6
XML Schemas Secure Data Communication With XML Schemas, the sender can describe the data in a way that the receiver will understand. A date like: "03-11-2004" will, in some countries, be interpreted as 3.November and in other countries as 11.March. However, an XML element with a data type like this: <date type="date">2004-03-11</date> ensures a mutual understanding of the content, because the XML data type "date" requires the format "YYYY-MM-DD". 7
XML Schemas are Extensible XML Schemas are extensible, because they are written in XML. With an extensible Schema definition you can: Reuse your Schema in other Schemas Create your own data types derived from the standard types Reference multiple schemas in the same document 8
A Simple XML Document <?xml version="1.0"?> <note> <to>Tove</to> <from>Jani</from> <heading>Reminder</heading> <body>Don't forget me this weekend!</body> </note> 9
An XML Schema <?xml version="1.0"?> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"targetNam espace="http://www.w3schools.com"xmlns="http://www.w3 schools.com" elementFormDefault="qualified"> <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>10
</xs:complexType> </xs:element> </xs:schema> The <schema> Element The <schema> element is the root element of every XML Schema <?xml version="1.0"?> <xs:schema>......</xs:schema> 11
xmlns:xs="http://www.w3.org/2001/XMLSchema" indicates that the elements and data types used in the schema come from the "http://www.w3.org/2001/XMLSchema" namespace. It also specifies that the elements and data types that come from the "http://www.w3.org/2001/XMLSchema" namespace should be prefixed with xs: 12
targetNamespace="http://www.w3schools.com" indicates that the elements defined by this schema (note, to, from, heading, body.) come from the "http://www.w3schools.com" namespace. This fragment: xmlns="http://www.w3schools.com" indicates that the default namespace is "http://www.w3schools.com". 13
XML Schemas define the elements of your XML files. A simple element is an XML element that contains only text. It cannot contain any other elements or attributes. Simple elements cannot have attributes. If an element has attributes, it is considered to be of a complex type. But the attribute itself is always declared as a simple type <xs:attribute name="xxx" type="yyy"/> where xxx is the name of the attribute and yyy specifies the data type of the attribute. 14
XML Schema has a lot of built-in data types. The most common types are: xs:string xs:decimal xs:integer xs:boolean xs:date xs:time 15

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uptu web technology unit 2 Xml2

  • 1. Web Technology (NCS-504) Prepared By Mr.Abhishek Kesharwani Assistant Professor,UCER Naini,Allahabad
  • 3. Introduction to XML Schema XML Schema is an XML-based alternative to DTD. An XML schema describes the structure of an XML document. The XML Schema language is also referred to as XML Schema Definition (XSD). 3
  • 4. Purpose of an XML Schema The purpose of an XML Schema is to define the legal building blocks of an XML document, just like a DTD. 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
  • 5. XML Schemas Support Data Types One of the greatest strength of XML Schemas is the support for data types. With support for data types: It is easier to describe allowable document content It is easier to validate the correctness of data It is easier to work with data from a database It is easier to define data facets (restrictions on data) It is easier to define data patterns (data formats) It is easier to convert data between different data types 5
  • 6. XML Schemas use XML Syntax Another great strength about XML Schemas is that they are written in XML.Some benefits of that XML Schemas are written in XML: You don't have to learn a new language You can use your XML editor to edit your Schema files You can use your XML parser to parse your Schema files You can manipulate your Schema with the XML DOM You can transform your Schema with XSLT 6
  • 7. XML Schemas Secure Data Communication With XML Schemas, the sender can describe the data in a way that the receiver will understand. A date like: "03-11-2004" will, in some countries, be interpreted as 3.November and in other countries as 11.March. However, an XML element with a data type like this: <date type="date">2004-03-11</date> ensures a mutual understanding of the content, because the XML data type "date" requires the format "YYYY-MM-DD". 7
  • 8. XML Schemas are Extensible XML Schemas are extensible, because they are written in XML. With an extensible Schema definition you can: Reuse your Schema in other Schemas Create your own data types derived from the standard types Reference multiple schemas in the same document 8
  • 9. A Simple XML Document <?xml version="1.0"?> <note> <to>Tove</to> <from>Jani</from> <heading>Reminder</heading> <body>Don't forget me this weekend!</body> </note> 9
  • 10. An XML Schema <?xml version="1.0"?> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"targetNam espace="http://www.w3schools.com"xmlns="http://www.w3 schools.com" elementFormDefault="qualified"> <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>10
  • 11. </xs:complexType> </xs:element> </xs:schema> The <schema> Element The <schema> element is the root element of every XML Schema <?xml version="1.0"?> <xs:schema>......</xs:schema> 11
  • 12. xmlns:xs="http://www.w3.org/2001/XMLSchema" indicates that the elements and data types used in the schema come from the "http://www.w3.org/2001/XMLSchema" namespace. It also specifies that the elements and data types that come from the "http://www.w3.org/2001/XMLSchema" namespace should be prefixed with xs: 12
  • 13. targetNamespace="http://www.w3schools.com" indicates that the elements defined by this schema (note, to, from, heading, body.) come from the "http://www.w3schools.com" namespace. This fragment: xmlns="http://www.w3schools.com" indicates that the default namespace is "http://www.w3schools.com". 13
  • 14. XML Schemas define the elements of your XML files. A simple element is an XML element that contains only text. It cannot contain any other elements or attributes. Simple elements cannot have attributes. If an element has attributes, it is considered to be of a complex type. But the attribute itself is always declared as a simple type <xs:attribute name="xxx" type="yyy"/> where xxx is the name of the attribute and yyy specifies the data type of the attribute. 14
  • 15. XML Schema has a lot of built-in data types. The most common types are: xs:string xs:decimal xs:integer xs:boolean xs:date xs:time 15