Quantifying the variability mismatch between problem and solution space

Abstract

A software product line allows to derive individual software products based on a configuration. As the number of configurations is an indicator for the general complexity of a software product line, automatic #SAT analyses have been proposed to provide this information. However, the number of configurations does not need to match the number of derivable products. Due to this mismatch, using the number of configurations to reason about the software complexity (i.e., the number of derivable products) of a software product line can lead to wrong assumptions during implementation and testing. How to compute the actual number of derivable products, however, is unknown. In this paper, we mitigate this problem and present a concept to derive a solution-space feature model which allows to reuse existing #SAT analyses for computing the number of derivable products of a software product line. We apply our concept to a total of 119 subsystems of three industrial software product lines. The results show that the derivation scales for real world software product lines and confirm the mismatch between the number of configurations and the number of products.