Validating the XML File

• Validation with DTD-s : the SGML inheritance. But:
  • namespaces are an unknown concept for DTDs!
  • only a few datatypes, but we would like to stipulate that
    • image dimensions must be positive integers, source should be valid URI
    • phone numbers should follow some pattern (eg, should begin with a '+')
    • etc
• XML Schemas are a better alternative
  • Schemas are in XML
    • no special syntax, special editor, validation is possible,...
  • Include a type system
    • over 30 predefined types, possibilities to extend and restrict