Summary

In this chapter you saw Tomcat’s proprietary system of valves that you can use to intercept requests. The various types of valve can block access to a resource, log details of the intercepted request, and log details of Web application access. You can also use valves to implement single sign-on, where a user can log into every Web application running on a server.

You also saw Tomcat’s session managers, which can ensure that user sessions are persisted across server restarts and crashes and can give Tomcat the ability to move inert sessions out of memory, thus boosting performance. You can configure the location of these sessions, with the choice being between files or JDBC data sources.

You also saw how you extend this mechanism with Tomcat’s clustering mechanism. This allows you to provide a more robust service to your users.