By focusing on the final solutions, the approaches ignore the fact that environments cannot stop their current activities and start with something new. In the figure, the effort typically required for delivering systems in a product line is illustrated. Three effort lines for three approaches are shown. The traditional product line approach needs only a minimal effort for delivering a particular instance. Product Line Infrastructure A product line approach that aims at minimizing the changes to an organization must be customizable, especially with respect to the used types of generic assets.
Generic assets are part of the product line infrastructure.
In this thesis, a technique for modeling variabilities is developed that modifies the assets already used for modeling single systems in an organization by extending their meta models. An investigation of the published product line approaches shows that a product line infrastructure contains, besides generic assets, a decision model that captures the domain knowledge needed to systematically employ a product line infrastructure. In this thesis, a technique for modeling decisions is developed that complements the technique for modeling variability. The incremental introduction of product line engineering using these techniques is validated in an experiment in which two groups of software developers are involved. The first group gets the specifications of three variants of a component, which are required for three members of a product line.