[libvirt] detection of events in kvm

[rash]

Hello,
      I am student and doing a project in virtualization.My project requires
detection of events in kvm like start of a virtual machine,shutoff of a
virtual machine.
      So I want to know if there is any way by which I can detect these
events.As in I want to write a code which will detect these events and then
handle them.I am using ubuntu 13.04.
      I would be glad if anyone can help me.

Thanks