We have a critical standalone java component in our application which needs to be up and running 24/7.We are looking for ways to monitor this component.Basically to check if it is alive all the time.
In case it goes down(considering all the worst possible scenarios),the administrator needs to be alerted.
tail -f on a logfile (if error or something -> sendmail or telnet)
a process which makes a ps -aef | grep java
for our web applications in the net we have "internal" (runs on the machine and works as described above) and external monitoring, this is another company which just calls a website and checks for content.