DB2 Express-C comes with XML and Web Services support already backed. There is a free e-book from the experts in all things DB2 that supposedly helps you get the most out of these functions. The author of the section on automatic maintenance and utility throttling, Roger Sanders has written enough books on DB2 to fill a small library. If you ever decide to prepare yourself for a DB2 certification, you will most likely be using one of Roger’s books.
Robert Catterall contributed the chapter on SOA performance. Robert has been working with DB2 since the dinosaurs roamed the earth (or just about).
XML performance chapter is written by Nelson King. Nelson has nine books to his credit and is a prolific blogger.
This promises to be a good read.