XML-DBMS
XML-DBMS is middleware for transferring data between XML documents and relational databases. It maps the XML document to the database according to an object-relational mapping in which element types are generally viewed as classes and attributes and PCDATA as properties of those classes. An XML-based mapping language allows the user to specify customize this mapping.
XML-DBMS is available both as a set of Java packages and as a PERL module (courtesy of Nick Semenov (nsemenov@yahoo.com)). XML-DBMS, along with its source code, is freely available for use in both commercial and non-commercial settings. It is not copyrighted and has absolutely no warranty. Use it as you will.