This package contains a very simple example of a pluggable datatype library.
The datatype library is implemented by the class
com.thaiopensource.datatype.sample.BalancedString.  The
bulk of the implementation is inherited from the abstract class
com.thaiopensource.datatype.sample.SimpleDatatypeLibrary,
which provides default implementations for the methods in the
interfaces which a datatype library must implement.  A class that
derives from SimpleDatatypeLibrary has only to implement
a boolean isValid(String literal) method.  The datatype
library has the URI
http://www.thaiopensource.com/relaxng/datatypes/sample,
and contains exactly one datatype, which is called
balancedString.  This datatype allows any string in which
parentheses are properly balanced (nested). To use this sample
datatype library, simply include datatype-sample.jar in
your CLASSPATH.  You will then be able to validate against schemas
using this additional datatype.  The file datatype-sample.rng is a simple RELAX
NG schema using this datatype; valid.xml is an
instance that is valid with respect to this schema; invalid.xml is an instance that is not valid
with respect to this schema.