Expressing feature-based variability in structural models

Software product line engineering aims at reducing development time, effort, cost, and complexity by tak-ing advantage of the commonality within a portfolio of similar products. The effectiveness of a software prod-uct line approach directly depends on how well feature variability within the portfolio is implemented and ma-naged throughout the development lifecycle, from early analysis through maintenance and evolution. This pa-per presents a tool-supported approach that improves variability management and tracing by providing means to express feature-based variability on model level. Features are separated in models and automati-cally composed. The approach supports both positive variability, i.e. adding optional parts to a model, as well as negative variability, i.e. removing parts from a model. Tools are provided that implement the pre-sented concepts. The approach is illustrated with a case study of a home automation system.