Contextual Goal Models for Dynamic Software Product Lines

Abstract

[Context] Dynamic Software Product Lines (DSPLs) are SPLs in which configuration occurs at runtime. DSPL approaches provide means for modelling variability as well as a configuration process for binding variability according to runtime changes in the context and/or non-functional requirements (NFRs). However, taking contexts and NFRs into account may result in multiple and, sometimes, conflicting possible configurations. Most of DSPL approaches do not provide means for prioritizing possible configurations in order to select one of them, and those that provide, do not take into account the NFRs’ priority for the current context. [Objective] In this work, we propose a Requirements Engineering (RE) approach for DSPL, ConG4DaS (Contextual Goal models For Dynamic Software product lines), which provides: (i) models for capturing variability with goals, NFRs, contexts and the relationship between them; and (ii) a configuration process that takes contexts, NFRs and their priority and interactions into account. [Method] We have used simulation based assessment to compare ConG4DaS with another approach with respect to the satisfaction level of the highest priority softgoal. We simulated several different contexts of two DSPL examples and compared the configurations generated by both approaches. We also performed a survey, using an online questionnaire, with RE and DSPL researchers to evaluate ConG4DaS perceived usefulness. [Results] In the simulation based assessment, in the configurations selected by ConG4DaS the number of positive contributions and the difference between the numbers of positive and negative contributions to the highest priority softgoal are greater than in the randomly selected configurations of the other approach. However, when comparing ConG4DaS configurations to the manually selected configurations of the other approach, there is no significant difference between them. In the survey, both groups of researchers (RE and DSPL) perceived ConG4DaS as useful for modelling and configuring DSPL variability. But the RE group gave more positive answers than the DSPL group.