Specification of invariability in OCL Specifying invariable system parts and views

摘要

The Object Constraint Language (OCL) is a high-level, object-oriented language for contractual system spec-ifications. Despite its expressivity, OCL does not provide primitives for a compact specification of invariability. In this paper, problems with invariability specification are listed and some weaknesses of existing solutions are pointed out. The question of invariability specification is addressed and a sim-ple but expressive extension of OCL is proposed. It allows a view-oriented specification of invariability constraints, wher-eby we restrict the notion of view to reducts based on order-sorted algebras. The semantics of this extension is defined in terms of standard OCL.