[Zope] how do I manage a graceful shutdown?

I want to do a graceful shutdown with a Product I'm writing. That is, I want to guarantee that some log files include a final message, maybe send an email to a site admin ... those sorts of things. Is there a "hook" that I can include in my product to make sure my shutdown stuff is called whenever Zope is shutting down or restarting? thanks! tim lynch tlynch@nal.usda.gov