I was wondering if someone could recommend a real time monitoring tool for j2ee apps (availability, performance, response time, etc). Preferably something free / open source.
I'm also interested about experiences in some type of home-grown solution - i.e. apply some sort of design (pattern??) that permits plugin something that could inform of performance/availability problems.. perhaps something modular that can be changed or even turned off if found not to be necessary. Of course, with minimal impact on the real functionality.
Faaarrr from free, we use Wily Introscope to great advantage. Mercury has a very similar tool and a vendor we work with has OEMd a third.
Their architecture is to modify byte code as the classes are loaded and add instrumentation. It's like AOP on the fly. The instrumented classes send metrics to a server that stores them, and the dashboard or console is a client server app that displays the metrics.
If you hear of any low cost tools that do the same thing, let us know!
A good question is never answered. It is not a bolt to be tightened into place but a seed to be planted and to bear more seed toward the hope of greening the landscape of the idea. John Ciardi
I am the creator of JAMon (Java Application Monitor) which is free and open source. It allows you to monitor page hits via a servlet filter. You simply add a few lines to web.xml. It can also monitor jdbc/sql/exceptions and interfaces and everything is visible via a web page. It also works in standard non web java apps (jdk 1.4 or higher).