In this paper we investigate the notion of transaction in object-oriented specification.

In the traditional formal approach to system specification and implementation, the software development process consists of a number of refinement steps which transform the initial specification into its correct realisation. This idealised view can hardly capture common situations when a specification changes in a non-incremental way, e.g. when client requirements change or new software technologies emerge. An extra flexibility can be added to the development process by allowing for a redesign of specifications, in addition to refinement steps. In this paper, the notion of specification redesign is formalised for an arbitrary institution.

Formal methods have been applied to reactive systems in order to capture errors early on in the development life-cycle and reduce redesign costs. The Reactive Systems Development Support (RSDS) method provides support for the analysis and design of reactive systems and generates code from these specifications. An RSDS system is specified by a set of invariants, a set of statemachines and a Data Control Flow Diagram (DCFD), which are then verified using the B theorem-prover. B however requires user interaction and is not capable of proving temporal properties easily. This thesis extends RSDS by integrating model checking so that temporal properties can be verified. The model checker used is the Symbolic Model Verifier (SMV). There are two distinct semantic views of statemachines in RSDS: the coarse-grain and the fine-grain, with the key difference between them being the granularity of a step. We describe a translation to SMV for each semantic view and we guarantee the quality of the translations by formally proving their correctness. This proof is a vital part in our provision of transparent formal method support for system design. To overcome the state explosion problem of model checking, we propose some natural ways of using the RSDS decomposition techniques for dividing the system

: Lowering costs for software maintenance, development and reuse is a great challenge. Strategies like the 3 schema architecture for databases has shown to lower maintenance and development costs of databases. For a similar purpose an architecture has been developed over the last 10 years for object-oriented systems. This architecture is now named the COIR architecture and has helped in lowering the cost of software maintenance, development and reuse, even enabling cost effective tailoring of software to small groups of users. Keywords: Object-oriented modelling, Object types, Reusable software. Research report No 197, Dep. of Informatics, Univ. of Oslo 3 The COIR architecture for Flexible Software Components and Systems by Else K. Nordhagen (lc@ifi.uio.no) Introduction This document presents a model of objects, the COIR architecture, which pictures objects as having properties which can be laid out in four dimensions. The four dimensions are: the Conceptual dimension the Observable ...

This paper presents work performed in the EPSRC "Object-oriented Specification of Reactive and Real-time Systems" project. It aims to extend the Object Calculus of Fiadeiro and Maibaum to cover durative actions, real-time constraints and hybrid systems. We define a core logic, termed "Real-time action logic" (RAL) which can provide an axiomatic semantics and reasoning framework for concurrent, real-time and object-oriented specification languages. The logic could also be viewed as providing the basis of a specification language in its own right. We combine RAL with the object-oriented specification language VDM ++ in order to provide a framework for specification and refinement of real-time systems. We show how a modal action logic (MAL) and real-time logic (RTL) for reasoning about concurrent object-oriented programs and specifications can be derived from RAL, and indicate how this formalism can be used to provide an axiomatic semantics for a large part of VDM ++ (so tha...

One of the many difficult tasks in requirements engineering for software-based systems is validation. The aspect of validation dealt with in this thesis is the justification that a proposed system, once implemented, will lead to the system in its environment displaying required behaviour. The work reported in this thesis is motivated by two problems with attempts at justification: . the need to reason about dependencies in composite systems . the need to carry out the re-justification of proposals as changes are made Solutions to both of these problems are found in the definition of a temporal logic and compositional reasoning method. These are based on the assumption/commitment approach to modelling, which was originally developed for reasoning about interference in concurrent systems. The approach is applied in this thesis in the area of requirements engineering through the provision of a highly modular style of object description in which: . the achievement of each object's commitme...