checking the status of my service

Hi. I am writing a service as well as a monitor program that I can use to
start and stop the service plus monitor it's performance. I am wondering if
there is a way that I can have an event in my monitor app get fired whenever
the service's state changes. Right now, in my montior app, I have a timer
that goes off every second and checks the status of the service. This doesn't
seem like the right way to do it. Please help if you can.