The signal-bearing medium of claim 20 wherein retrieving data further comprises retrieving multiple distinct service variables specified in the service level agreement; wherein determining what value the at least one service variable will assume further comprises determining what value each distinct service variable will assume during the service delivery event; and wherein retrieving a service delivery model in dependence on the value that the at least one service variable will assume further comprises retrieving a service delivery model in dependence on the value each service variable will assume during the service delivery event.