J2EE Applications Servers are independent from the database layer. As they are made thinking about a 3-tier application architecture where the presentation (Web/SWING/WAP/Corba/etc), businness logic (the appserver with your app), and data (DB2/Oracle/etc) are separated, independend and interchangeable. Of course, as DB2 comes from IBM, WebSphere can be a natural candidate, but it doesn't matter at all.