Generate list of active running jobs inside a protocol?

Is it possible to get a list of actively running jobs from within a PP protocol?  I'd like to be able to ensure that a given protocol can't be run concurrently.  I.e. if user 1 runs "massive backup protocol that takes an hour to run" and user 2 launches the same protocol 10 minutes later, I want to be able to show a message telling user 2 that the protocol is already running.​