XML Schema
An XML Schema describes the structure of an XML document, just like a DTD.
An XML document with correct syntax is called "Well Formed".
An XML document validated against an XML Schema is both "Well Formed" and "Valid".
XML Schema
XML Schema is an XML-based alternative to DTD:
>
The Schema above is interpreted like this:
- <xs:element defines the element called "note"
- <xs:complexType> the "note" element is a complex type
- <xs:sequence> the complex type is a sequence of elements
- <xs:element the element "to" is of type string (text)
- <xs:element the element "from" is of type string
- <xs:element the element "heading" is of type string
- <xs:element the element "body" is of type string
XML Schemas are More Powerful than DTD
- XML Schemas are written in XML
- XML Schemas are extensible to additions
- XML Schemas support data types
- XML Schemas support namespaces
Why Use an XML Schema?
With XML Schema, your XML files can carry a description of its own format.
With XML Schema, independent groups of people can agree on a standard for interchanging data.
With XML Schema, you can verify data.
XML Schemas Support Data Types
One of the greatest strength of XML Schemas is the support for data types:
- It is easier to describe document content
- It is easier to define restrictions on data
- It is easier to validate the correctness of data
- Schemas with the XML DOM
- You can transform your Schemas with XSLT
If you want to study XML Schema, please read our XML Schema Tutorial.