try {
// Load the JDO database configuration file from the specified
// input source. If the database was already configured, ignore
// this file (allowing multiple loadings).
if ( resolver == null )
unm.setEntityResolver( new DTDResolver() );
else
unm.setEntityResolver( new DTDResolver( resolver ) );
database = (Database) unm.unmarshal( source );
if ( _databases.get( database.getName() ) != null )
return;
// Complain if no database engine was specified, otherwise get