Model-Based System Architecture

Chapter 15Product Lines & Variants

Many systems exist in different configurations: A product line, a customized product, or different designs for trade studies. Typically, a single variant of a system affects only a few parts of the system. It is a slight derivation from the initial system. However, it is not possible to quantify the number or level of detail that varies to be still a variant of a system and not a complete new system.

A car as well as an aircraft could be a variant of a transportation system. However, in most cases, it makes no sense in practice to handle a car and an aircraft as variants of the same system and to manage all the appropriate relationships in a single system model. The common parts of a transportation system are too abstract. Unfortunately, you can't measure abstraction and we cannot give an objective metric. You must decide if the abstraction levels of the common parts and the abstraction level of the variant parts are close enough to be valuable to be part of the same model. The benefit must be larger than the effort to manage a complex model.

The description of variants is a sophisticated task. It is already challenging to create a good description of a single system. Each variation adds another dimension to a multidimensional system model. For instance, the engine could be a variation of a car system with three possible variants: diesel, electric, or hybrid engine. Next variation could be the chassis: small, deluxe, or cabriolet. Now you can ...