Defining custom EL functions

I've been working on porting my sandbox webapp to Spring WebMVC, and in the process I've been learning more about JSP as well. This work led me to ask a question at StackOverflow, a favorite site of mine for a while for finding solutions to problems, though I've only recently begun participating.
In the question I asked about the best way to sort a single List in different ways in JSP, and I didn't get any answers that I really liked, so I kept looking and found an answer that I was able to use to suit my needs. You can see my solution at StackOverflow, but I'll reproduce it here as well.

Forwarding traffic from Apache2 to Tomcat on Ubuntu

I have several Java webapps running under Tomcat that I wanted to be accessible through Apache2 running on port 80 on my home server. It turns out that it's pretty easy to do, though I didn't find an example anywhere that included all the steps I needed to take to get it working. Most of what I need to know was at this blog post.

First of all, here are the exact versions I'm running. I wouldn't be surprised if there are newer major versions; I need to upgrade the server.

• Apache2: 2.2.11
• Tomcat: 6.0.18

We're going to proxy traffic back and forth between Apache2 and Tomcat using Apache JServ Protocol. Apache ships with support through the module proxy_ajp, and Tomcat has a built-in connector.