To implement the application you obviously need Java and AspectJ. In addition, I chose to use the following open source software:
Tomcat JSP/Servlet engine
MySQL relational database
Ant build utility
There is no particular reason for any of the selections beside easy availability; anyone with enough patience can obtain, install, and configure them. Furthermore, any other servlet engine combined with a relational database that has a JDBC driver will do just fine, and a build tool is a matter of personal or organizational preference, anyway. Appendix C, "Auxiliary Tools," contains more details about these tools including version numbers, licensing, and configuration information.