I still don't see the problem. And I am not sure if I understand what you mean, by you not wanting the client to know about the sybase operation? Do you mean you don't want the client to realize they are using a database, or you are afraid of the client looking in the code of the class files and finding the information on how to get into the database illegally?
Both are easily solved and probably easier than getting into JNI operations.
As far as using a DLL, definatly look into
JNI [ September 09, 2002: Message edited by: Gregg Bolinger ]