"anyType" Built-in Datatype Values and Representations

XSD Tutorials - Herong's Tutorial Examples

∟"anyType" Built-in Datatype Values and Representations

This section provides a tutorial example to show built-in datatype 'anyType' valid values and representations. Everything, including XML structure, is a valid 'anyType' lexical representation.

To fully understand built-in datatypes defined in XSD 1.1, we need to spend time to read the specification and writing test XSD documents and XML documents for each datatype. Let's start with the first special built-in datatype "anyType" in this section.

"anyType" is a built-in datatype designed to be a wildcard datatype to represent any simple or complex values with these rules:

The value space of "anyType" is all possible simple values (strings of characters) and all possible complex values (XML structures).
The lexical space of "anyType" is the same as the value space.
An "anyType" lexical representation is parsed to an "anyType" value by taking the representation as is. This means that everything is valid in an "anyType" element.
"anyType" is a complex type, it can only be used to declare XML elements. It is not allowed for declaring XML attributes.

To verify these rules, I wrote this simple XSD document:

<?xml version="1.1"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
<!-- anyType_datatype_test.xsd
 - Copyright (c) 2002-2013 HerongYang.com. All Rights Reserved.
-->
<xs:element name="AnyType_Datatype_Test">
  <xs:complexType>
    <xs:sequence>
      <xs:element name="AnyType" type="xs:anyType"
        maxOccurs="unbounded"/>
    </xs:sequence>
  </xs:complexType>
</xs:element>
</xs:schema>

With <AnyType> element is declared as "anyType", anything can be placed inside the element. Here is an XML document with some examples:

<?xml version="1.1"?>
<AnyType_Datatype_Test>
<!-- anyType_datatype_test.xml
 - Copyright (c) 2002-2013 HerongYang.com. All Rights Reserved.
-->
<!-- Everything is valid in "AnyType" elements -->
  <AnyType>   Everything is valid! </AnyType>
  <AnyType>   1971-05-16T00:00:01  </AnyType>
  <AnyType>   &#x5934;             </AnyType>
  <AnyType>   Hello <b>Herong</b>! </AnyType>
  <AnyType>   Hello <b size="9">Herong</b>! </AnyType>
  <AnyType>
     <AnyType>   Hello <b size="9">Herong</b>! </AnyType>
  </AnyType>
</AnyType_Datatype_Test>

If you want validate this XML document, you can try it the Java XSD validation tool I wrote earlier in this book. You will get no errors:

herong> javac XsdSchemaValidator.java

herong> java XsdSchemaValidator
^^^anytype_datatype_test.xsd anytype_datatype_test.xml

Passed.

To show you that "anyType" is not allowed for declaring XML attributes, I wrote this invalid XSD document:

<?xml version="1.1"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
<!-- anyType_datatype_invalid_test.xsd
 - Copyright (c) 2002-2013 HerongYang.com. All Rights Reserved.
-->
<xs:element name="AnyType_Datatype_Test">
  <xs:complexType>
    <xs:sequence>
      <xs:element name="AnyType" type="xs:anyType"
        maxOccurs="unbounded"/>

      <xs:element name="Attribute_Test" maxOccurs="unbounded">
        <xs:complexType>
          <!-- "anyType" is a complex type.
               It can not be used for attributes -->
          <xs:attribute name="AnyType" type="xs:anyType"/>
        </xs:complexType>
      </xs:element>

    </xs:sequence>
  </xs:complexType>
</xs:element>
</xs:schema>

If you validate the same example XML document with this XSD document, you will see this error:

herong> java XsdSchemaValidator
^^^ anyType_datatype_invalid_test.xsd anytype_datatype_test.xml

org.xml.sax.SAXParseException; systemId:
   anyType_datatype_invalid_test.xsd;
   lineNumber: 16; columnNumber: 59; src-resolve:
   Cannot resolve the name 'xs:anyType' to a(n)
   'simpleType definition' component.

java.lang.NullPointerException