Tim McComb

Refactoring object-z specifications

Object-Z offers an object-oriented means for structuring formal specifications. We investigate the application of refactoring rules to add and remove structure from such specifications to forge object-oriented designs. This allows us to tractably move from an abstract functional description of a system toward a lower-level design suitable for implementation on an object-oriented platform.

Architectural design in object-Z

We present a process for introducing an object-oriented architecture into an abstract functional specification written in Object-Z. Since the design is derived from the specification, correctness concerns are addressed as pan of the design process. We base our approach on refactoring rules that apply to class structure, and use the rules to implement design patterns. As a motivating example, we introduce a user-interface design that follows the model-view-controller paradigm into an existing specification.

Illoura™: a software tool for analysis, visualization and semantic querying of cellular and other spatial biological data

UNLABELLED New high-resolution approaches for mapping ultrastructure of cells in 3D are leading to unprecedented quantities of spatial data. Here we present Illoura, a software tool for the integrated management, analysis and visualization of these data within a semantic context, and illustrate its capability by analysis of spatial relationships in mammalian beta cells. AVAILABILITY http://www.visiblecell.com/illoura. SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.

SIFA: a tool for evaluation of high-grade security devices

We describe a tool for analysing information flow in security hardware. It identifies both sub-circuits critical to the preservation of security as well as the potential for information flow due to hardware failure. The tool allows for the composition of both logical and physical views of circuit designs. An example based on a cryptographic device is provided.

Animation of Object-Z specifications using a Z animator

We discuss a methodology for animating the Object-Z specification language using a Z animation environment. Central to the process is the introduction of a framework to handle dynamic instantiation of objects and management of object references. Particular focus is placed upon building the animation environment through pre-existing tools, and a case study is presented that implements the proposed framework using a shallow encoding in the Possum Z animator. The animation of Object-Z using Z is both automated and made transparent to the user through the use of a software tool named O-zone.

Compositional class refinement in object-z

Object-Z allows coupling constraints between classes which, on the one hand, facilitate specification at a high level of abstraction, but, on the other hand, make class refinement non-compositional. The consequence of this is that refinement is not practical for large systems. This paper overcomes this limitation by introducing a methodology for compositional class refinement in Object-Z. The key step is an equivalence transformation of an arbitrary Object-Z specification to one in which introduced constraints prohibit non-compositional refinements. The methodology also allows the constraints which couple classes to be refined yielding an unrestricted approach to compositional class refinement.

A Minimal Set of Refactoring Rules for Object-Z

This paper presents a minimal and complete set of structural refactoring rules for the Object-Z specification language that allow for the derivation of arbitrary object-oriented architectures. The rules are equivalence preserving and work in concert with existing class refinement theory, so that any design derived using the rule set can be shown to be equivalent to, or a refinement of, the original specification.

MDA-Based re-engineering with object-z

This paper describes a practical application of MDA and reverse engineering based on a domain-specific modelling language. A well defined metamodel of a domain-specific language is useful for verification and validation of associated tools. We apply this approach to SIFA, a security analysis tool. SIFA has evolved as requirements have changed, and it has no metamodel. Hence, testing SIFAs correctness is difficult. We introduce a formal metamodelling approach to develop a well-defined metamodel of the domain. Initially, we develop a domain model in EMF by reverse engineering the SIFA implementation. Then we transform EMF to Object-Z using model transformation. Finally, we complete the Object-Z model by specifying system behavior. The outcome is a well-defined metamodel that precisely describes the domain and the security properties that it analyses. It also provides a reliable basis for testing the current SIFA implementation and forward engineering its successor.

Refactoring Real-time Specifications

This paper presents an approach to refactoring real-time specifications written using Real-Time Object-Z. This allows implementation components such as clocks and sensors, not necessarily present in an initial abstract specification, to be introduced via a sequence of refinement steps. The approach, based on similar work for Object-Z, is enabled by a semantics of object instantiation and operation synchronisation introduced in this paper. Means of refining synchronising operations to reflect the timing and causality constraints of an implementation are also presented.

Verifying abstract information flow properties in fault tolerant security devices

The verification of information flow properties of security devices is difficult because it involves the analysis of schematic diagrams, artwork, embedded software, etc. In addition, a typical security device has many modes, partial information flow, and needs to be fault tolerant. We propose a new approach to the verification of such devices based upon checking abstract information flow properties expressed as graphs. This approach has been implemented in software, and successfully used to find possible paths of information flow through security devices.