Systematic quality trade-off support in the software product-line configuration process

Software product line engineering is a compelling methodology that accomplishes systematic reuse in families of systems by relying on two key principles: (i) the decomposition of complex systems into composable and reusable building blocks (often logical units called features), and (ii) on-demand construction of products and product variants by composing these building blocks. However, unless the stakeholder responsible for product configuration has detailed knowledge of the technical ins and outs of the software product line (e.g., the architectural impact of a specific feature, or potential feature interactions), he is in many cases flying in the dark. Although many initial approaches and techniques have been proposed that take into account quality considerations and involve trade-off decisions during product configuration, no systematic support exists. In this paper, we present a reference architecture for product configuration tooling, providing support for (i) up-front generation of variants, and (ii) quality analysis of these variants. This allows pro-actively assessing and predicting architectural quality properties for each product variant and in turn, product configuration tools can take into account architectural considerations. In addition, we provide an in-depth discussion of techniques and tactics for dealing with the problem of variant explosion, and as such to maintain practical feasibility of such approaches. We validated and implemented our reference architecture in the context of a real-world industrial application, a product-line for the firmware of an automotive sensor. Our prototype, based on FeatureIDE, is open for extension and readily available.