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This paper presents a method for test scenario generation based on formal specifications and usage profiles. It is a major component of a framework for testing object-oriented programs. In this framework, the requirements of a software system are formally specified. The anticipated application of the system is expressed in a usage profile, which is a state model that indicates the dynamic behavior of the system and execution probabilities for the behaviors. The state model is used as a guide to derive the anticipated operation scenarios. An enhanced state transition diagram is used to represent the state model, which incorporates hierarchy, usage and parameter information. Since the number of feasible scenarios can be extremely large, probability and importance criteria are used to select the most probable and important scenarios.

A Use Case Map (UCM) is a scenario-based visual notation facilitating the requirements definition of complex systems. A UCM may be generated either from a set of informal requirements, or from a set of use cases normally expressed in natural language. Natural languages are, however, inherently ambiguous and as a semi-formal notation, UCMs have the potential to bring more clarity into the functional description of a system. It may furthermore eliminate possible errors in the user requirements. The semi-formal notation of UCMs aims to show how things work generally, but is not suitable to reason formally about system behavior. It is plausible, therefore, that the use of a UCM as an intermediate step may facilitate the construction of a formal specification. To this end this paper proposes a mechanism whereby a UCM may be translated into Object-Z.

Formal specification languages provide assistance to solving the problem of high maintenance costs caused by ineffective communication of a system’s requirements. Using a sound mathematical basis, a formal specification language provides a precise and definitive system description that can serve as a binding contract. Additionally, the integration of the object-oriented paradigm with a formal specification language provides increased potential for software reuse, conceptually cleaner specifications and a framework for defining interfaces. To this end, there has been significant work done to extend existing specification languages to allow object-oriented specifications.

This paper provides a comparison of such object-oriented specification languages, specifically, those extending Z. The paper is organized into five major sections. After a brief introduction to the concepts of formal specification languages and Z, a simple library system is defined and used as an example throughout the paper. Each of the object-oriented specification languages is introduced and classified as either using Z in an object-oriented style or providing a true object-oriented extension of Z. For each language, the specification of the example library system is presented following a brief overview of the language’s features. An in-depth comparison is made of each of the languages which provide a true object-oriented extension of Z.

We present HiLLS (High Level Language for System Specification), a graphical formalism that allows to specify Discrete Event System (DES) models for analysis using methodologies like simulation, formal methods and enactment. HiLLS’ syntax is built from the integration of concepts from System Theory and Software Engineering aided by simple concrete notations to describe the structural and behavioral aspects of DESs. This paper provides the syntax of HiLLS and its simulation semantics which is based on the Discrete Event System Specification (DEVS) formalism. From DEVS-based Modeling and Simulation (M&S) perspective, HiLLS is a platform-independent visual language with generic expressions that can serve as a front-end for most existing DEVS-based simulation environments with the aid of Model-Driven Engineering (MDE) techniques. It also suggests ways to fill some gaps in existing DEVS-based visual formalisms that inhibit complete specification of the behavior of complex DESs. We provide a case study to illustrate the core features of the language.

The paper proposes an XML format for Object-Z specification language. We describe several markup format of Object-Z language and compare some existing works, the problems and the issues that arose, and propose a new XML markup format of Object-Z specification language. The new proposal considered the particular requirement of Object-Z specification animation and demonstrates the feasibility and validity by an example.