Introduction to TopLink Object-XML Mapping  By Blaise Doughan
Object-XML Impedance Mismatch  XML is a common format for the
exchange of data. XML is human readable and it is portable
making it the perfect format for exchanging data between
applications running on different platforms (i.e. Web Services).
However, for many applications objects are the preferred
programmatic representation not XML. XML has become pervasive in
the modern software world, so to work at the object-level, the
data needs to be converted to object form. Analogous to the
better-known object-relational impedance mismatch, a similar
mismatch also exists with objects and XML.  Why not just use
DOM, SAX, or StAX?  These APIs only provide low-level access to
XML data and for many applications; a higher level of object
abstraction is required. Even though DOM provides an in memory
tree structure that can be navigated these are not the domain
objects that developers are used to dealing with.   In this
example, a small schema fragment is exam