A Feature-Oriented Modelling Language and a Feature-Interaction Taxonomy for Product-Line Requirements

TL;DR: The thesis identifies the problem of developing a suitable language for expressing feature-oriented models of the functional requirements of an SPL, and presents the feature- oriented requirements modelling language (FORML) as a solution to this problem.

Abstract: Many organizations specialize in the development of families of software systems, called software product lines (SPLs), for one or more domains (e.g., automotive, telephony, health care). SPLs are commonly developed as a shared set of assets representing the common and variable aspects of an SPL, and individual products are constructed by assembling the right combinations of assets. The feature-oriented software development (FOSD) paradigm advocates the use of system features as the primary unit of commonality and variability among the products of an SPL [2]. A feature represents a coherent and identi able bundle of system functionality [89], such as call waiting in telephony and cruise control in an automobile. Furthermore, FOSD advocates feature-oriented artifacts (FOAs); that is, software-development artifacts that explicate features, so that a clear mapping is established between a feature and its representation in di erent artifacts. The thesis rst identies the problem of developing a suitable language for expressing feature-oriented models of the functional requirements of an SPL, and then presents the feature-oriented requirements modelling language (FORML) as a solution to this problem. FORML's notation is based on standard software-engineering notations (e.g., UML class and state-machine models, feature models) to ease adoption by practitioners, and has a precise syntax and semantics to enable analysis. The novelty of FORML is in adding feature-orientation to state-of-the-art requirements modelling approaches (e.g., KAOS [91]), and in the systematic treatment of modelling evolutions of an SPL via enhancements to existing features. An existing feature can be enhanced by extending or modifying its requirements. Enhancements that modify a feature's requirements are called intended feature interactions. For example, the call waiting feature in telephony intentionally overrides the basic call service feature's treatment of incoming calls when the subscriber is already involved in a call. FORML prescribes di erent constructs for specifying di erent types of enhancements in state-machine models of requirements. Furthermore, unlike some prominent approaches (e.g., AHEAD [11], DFC [94]), FORML's constructs for modelling intended feature interactions do not depend on the order in which features are composed; this can lead to savings in analysis costs, since only one rather than (possibly) multiple composition orders need to be analyzed. A well-known challenge in FOSD is managing feature interactions, which, informally de ned, are ways in which di erent features can in uence one another in de ning the overall properties and behaviours of their combination [93]. Some feature interactions are intended, as described above, while other feature interactions are unintended : for example, the cruise control and anti-lock braking system features of an automobile may have incompatible a ects on the automobile's acceleration, which would make their combination inconsistent.