Port listening, cron jobs and loading rails environment

As part of a web application that I am writing I need to have something
listening for any packets that are received on a particular port and
then process the packets using some of my Rails models, hence I start
the script via the ./script/runner command.
This script always needs to be running, if it exits for any reason, I
need it to start up again very quickly. Hence, I was considering
writing a simple script that gets called every minute via a cron job.
This script will check to see if anything is currently listening on the
particular port, and if not, call the script/runner command to start the
listener script again.
Does this seem like a reasonable way of making sure my listener script
is always running or is there another/better way?

monit is right up to your needs