Java GSS-API is used for securely exchanging messages between communicating applications. The Java GSS-API contains the Java bindings for the Generic Security Services Application Program Interface (GSS-API) defined in RFC 2853. GSS-API offers application programmers uniform access to security services atop a variety of underlying security mechanisms, including Kerberos.
For a general overview of JGSS, see Oracle's documentation of JGSS. The documents at this Web site contain links to many other Web-based information sources.