The basic database functionality is provided by the ADODB library (http://adodb.sourceforge.net); atop the ADODB library is an additional layer of abstraction provided by the Data Access Objects (DAOs). These make use of a few base classes in the classes/db directory that are extended to provide specific functionality.
DAORegistry.inc.php: This implements a central registry of Data Access Objects; when a DAO is desired, it is fetched through the DAO registry.DBConnection.inc.php: All database connections are established via this class.DAO.inc.php: This provides a base class for all DAOs to extend. It provides functions for accessing the database via the DBConnection class.In addition, there are several classes that assist with XML parsing and loading into the database:
XMLDAO.inc.php: Provides operations for retrieving and modifying objects from an XML data sourceDBDataXMLParser.inc.php: Parses an XML schema into SQL statements