Systems-of-Systems and Use Cases: An Insulin Pump System Example (9 min video with captions)

I tend think use cases are great before they force you to think about your system boundary. That said, I've been in plenty of meetings where everybody is agreeing on the use case, but participants actually have completely different perceptions of the system context. Like the statement "controlling the speed has nothing to do with my system, it's done by this other system" is an interesting one when talking about Cruise Control. Clearly if your system is a vehicle then the system will be controlling the speed. If your system is a sub-set of the vehicle, then it will depend on which bit you own.

In this video I walk through an example of an insulin pump system, or more precisely, two systems that relate to an insulin management system to show how each level can have use cases, but that the use cases differ in the level of abstraction. The key is that the concept of abstraction allows us to deal with complexity at the system-of-system level by focusing on essential detail only. It's also abstraction that enables us to keep things valid and current as the detail is fleshed out. My view is that one should create different use cases at each level and give ownership to the teams. Like when a sky-diver jumps out of an airplane, the first thing they look for is not the gate in the field. The same thing applies with models. This video illustrates using an Insulin Pump Management System to illustrate the value of abstraction. It shows shows an example of how to use Rhapsody's Allocation Wizard to allocate system functions to parts of a system.