How to kill/restart a HTTP::Daemon perl script properly.

I've written a small HTTP server using the HTTP::Daemon module and am
wanting to also generate a systemd service (please no flames :) for it. 
I know that it, my script, forks multiple children and I see in the
sample code that I used as a template, it keeps the pids in a hash.  I
suspect I can trap the signal that "systemctl stop xxx" throws and
iterate through that hash to kill them off one by one.  I know that
killing the original process ID with HUP doesn't terminate the children
so before I waste a whole lot of time I thought I'd ask someone who
knows more about the "proper" way to do it.

I did see something about SIG but I didn't quite understand what it was
doing.  I did try to kill the original process with TERM since it was
mentioned, but that didn't work either.

Thanks for any info.

Jim.