How to specify a daemon shutdown command with upstart?

How to specify a daemon shutdown command with upstart?

In an upstart configuration how do I define what command should be used to
shutdown a server. Lets say I have daemon that has two seperate processes.
startup.sh - to start the server
shutdown.sh - to shut down the server
Suppose I have an upstart file that looks like this.
description "Some Example Service"
author "Me"
start on runlevel [2345]
stop on runlevel [016]
respawn
exec satrtup.sh
How do I tell upstart that it should called shutdown.sh when shutting down
the server? How does upstart normally expect to shut down a daemon?