Most large-scale service delivery settings involve complex collections of interdependent services. The services of interest, in this context, could be web services or business services – much of the discussion below applies in either case. Consider the services that would be offered by an airport (the focus in this example being on business services), such as passenger check-in, baggage handling, passenger security screening, customs, cargo handling, food courts, lounges, aircraft refelling, aircraft maintenance and air traffic control (to name just a few). There are several aspects of service delivery settings such as these that make it necessary to define specialized machinery to support the design and redesign of service collections. First, the number, scale and complexity of the services on offer are large. Second, most of these services are interdependent (both in terms of design and execution).