With WebObjects 5, all database access goes through the JDBC Adaptor. JDBC is widely supported by database vendors, but not every data source behaves exactly the same way. As a result, the adaptor uses a helper class, a subclass of JDBCPlugIn, to customize the JDBC adaptor for a particular database or driver.
The JDBC Adaptor for WebObjects 5 ships with built-in support for Oracle 8i and OpenBase. Other data sources may require additional support from custom plugins. This technical note, as well as an example, can be found on Apple's Developer Web site (http://developer.apple.com/technotes/tn/tn2027.html).