Java EE (Java Enterprise Edition) General Discussion

Hello everyone.

What would be the best way or a good way to monitor topcat, so i could see when and where any errors are originating from, say if 10 people an hour are getting a certain http error code then I can work out why and enable me to see how much load tomcat is under and how it's performing?

I found Lambaprobe but it dosent seem to have been updated in 3 years and im not sure about it supporting tomcat 6.

To paraphrase, how do you know when it's time (or nearly time) to upgrade your Tomcat set up (vertical, horizontal, whatever)

Thanks for any (much needed) advice...