What is the difference between xsd and xsi?
What exactly is the difference between XML Schema Document and XML Schema Instance ?
- Both are XML namespace prefixes, abbreviations for an XML namespace.
- Both are, as are all namespace prefixes, arbitrarily named; other namespace prefix abbreviations
could equally well be used. However, both prefixes are conventional and therefore
recommended. (An also-conventional alternative to
xs) prefix referring to the Schema Namespace (
http://www.w3.org/2001/XMLSchema) is used in XML Schemas (XSDs) for the elements, attributes, and types of the W3C XML Schema Recommendation itself. (This is possible because XML Schema is itself XML.)
xsiprefix referring to the The Schema Instance Namespace
http://www.w3.org/2001/XMLSchema-instanceis used in XML document instances for several special attributes defined by the XML Schema Recommendation:
xsi:typeallows an XML instance to associate element type information directly rather than through an XSD. See How to restrict the value of an XML element using xsi:type in XSD?
xsi:nilallows an empty element to be considered to be valid when the XSD might not otherwise have allowed it.
xsi:noNamespaceSchemaLocationprovide hints to the XML processor as to how to associate an XSD with an XML document. Use
xsi:schemaLocationwhen there is a namespace; use
xsi:noNamespaceSchemaLocationwhen there is no namespace.