1) The J2EE Architect's Handbook ==>
http://www.theserverside.com/news/1369773/Free-Book-The-J2EE-Architects-Handbook
2) J2EE Best Practices: Java Design Patterns, Automation, and Performance ==>
http://eu.wiley.com/WileyCDA/WileyTitle/productCd-0471228850.html
3) Software Architecture in Practice ==>
http://www.amazon.com/Software-Architecture-Practice-Len-Bass/dp/0201199300
4) J2EE Performance Testing by Peter Zadrozny, Philip Aston, and Ted Osborne (Paperback - July 11, 2003)
5) Pro Java EE 5 Performance Management and Optimization by Steven Haines (Hardcover - May 11, 2006)
6) Java Performance Tuning (2nd Edition) by Jack Shirazi (Paperback - Jan. 2003)
7) Java Enterprise Best Practices by Robert Eckstein, J. Steven Perry, and O'Reilly Authors (Paperback - Dec. 2002)
8) Building Scalable and High-Performance Java Web Applications Using J2EE Technology by Greg Barish (Paperback - Dec. 27, 2001)
Marco