An Object-Oriented Structuring for Z Based on Views

Abstract

Abstract. There is significant interest in the use of Z in conjunction with object-orientation. Here we present a new approach to structuring Z specifications in an object-oriented (OO) style. Our structuring is based on views, it uses the schema calculus, and it does not extend Z. The resulting OO Z specifications are comprehensible, modular, and conceptually clear. The modularity of the new approach supports a templateinstantiation approach to expressing OO models in Z; practical formal verification and validation of the model can be undertaken using metaproof, meta-lemmas, and formal snapshots.

Specifying Structural Properties and Their Constraints Formally, Visually and Modularly Using VCL

“…This paper presents part of our ongoing work on VCL, a visual language for abstract specification of software systems. VCL uses our previous result, ZOO [15,5], a semantic domain of object-orientation expressed in language Z, which is well studied; it has been applied to several case studies published in the literature. This enables us to focus on the visual aspects of VCL; a result of work presented here is that we can describe visually structures that previously could only be described textually in Z.…”

“…Metamodels of VCL notations presented here were formally defined in Alloy (see [14]), and refined into concrete syntax metamodels implemented in VCL's visual contract builder tool 4 (an Eclipse plug-in based on GMF framework 5 ). Alloy was of great help in defining VCL's syntax: (a) it enabled [15] 215 195 91%…”

“…The semantics of a VCL specification is the generated target language specification. This paper uses Z as target language and ZOO [15,5] as semantic domain. ZOO is an abstract OO semantic domain for language Z.…”

“…VCL is illustrated here with simple Bank case study, which is also used to illustrate the ZOO semantic domain in [15,5]. The case study's requirements are given in table 1.…”

“…VCL gives the specifier the choice of writing a constraint visually or textually. Assuming a sum operator defined in the target language toolkit (see [15] for details), constraint TotalBalanceIsPositive (Fig. 7) is expressed in Z; its text is embedded in VCL CntD.…”