Should Future Variability Modeling Languages Express Constraints in OCL?

Abstract

Since the mid-2000s, Propositional Logic (PL) has been the de facto language to express constraints in Feature Models (FMs) of Software Product Line (SPLs). PL was adequate because product configurations were formed by binary decisions including or not including features in a product. Inspired by both prior research and practical systems (eg., SPLs that use KConfig), future FMs must go beyond PL and admit numerical (and maybe even text) variables and their constraints. The Object Constraint Language (OCL) is a general-purpose declarative constraint language for Model Driven Engineering (MDE), which admits virtually any kind of variable and constraint in metamodels. We should expect future FMs to be examples of MDE metamodels. This raises a basic question: Should OCL be used to express constraints of future variability modeling language(s)? In this talk, I outline the pros and cons for doing so.