MySQL Cookbook, 2nd Edition

Using MySQL for Session-Backing Store with Tomcat

Problem

You want to use session storage for Java-based scripts.

Solution

Tomcat handles session management for you. By default, it uses temporary files for backing store, but you can configure it to use MySQL instead by supplying the appropriate JDBC parameters in Tomcat’s server.xml configuration file.

Discussion

The Perl, Ruby, and PHP session mechanisms described earlier in this chapter require applications to indicate explicitly that they want to use MySQL-based session storage. For Perl and Ruby, a script must state that it wants to use the appropriate session module. For PHP, the session manager is built into the language, but each application that wants to use a MySQL storage module must register it.

For Java applications that run under Tomcat, a different framework applies. Tomcat itself manages sessions, so if you want to store session information in MySQL, you do so by reconfiguring Tomcat, not your applications. In other words, web-based Java programs are relieved of some of the messy session-related details that must be handled at the application level in other languages. For example, session IDs are handled by the Tomcat server rather than at the application level. If cookies are enabled, Tomcat uses them. Otherwise, it uses URL rewriting to encode the session ID in the URL. Application developers need not care which method is used because the ID is available to them the same way regardless of how it’s transmitted.

To illustrate ...