Purposeful performance variability in software product lines: a comparison of two case studies

Within software product lines, customers may have different quality needs. To produce products with purposefully different quality attributes, several challenges must be addressed. First, one must be able to distinguish product quality attributes to the customers in a meaningful way. Second, one must create the desired quality attribute differences during product-line architecture design and derivation. To study how performance is varied purposefully in software product lines, we conducted a comparison and re-analysis of two industrial case studies in the telecommunication and mobile game domains. The results show that performance variants must be communicated to the customer in a way that links to customer value and her role. When performance or its adaptation are crucial for the customer, performance differences must be explicitly "designed in" with software or hardware means. Due to the emergent nature of performance, it is important to test performance and manage how other variability affects performance.