AN EXECUTABLE SPECIFICATION FORMALISM REPRESENTING ABSTRACT DATA TYPES

It has been proved to be very useful and necessary to give formal specifications of software systems to be developed. The specifications should help to avoid the necessity of creating prototypes by offering direct executability. A useful specification language aiming the description of abstract data types - while maintaining abstractness - should also support the representation of states of objects, as well as support the transformation of declarative specifications into efficiently executable code. The present paper is intended to give an informal description of a specification language aimed to offer the features discussed above. Although the development of the language has mainly been motivated by the object-oriented language (OMOHUNDRO, 1993), it is intended to function as a specification formalism at a much broader field

Embedding object-oriented design in system engineering

The Unified Modeling Language (UML) is a collection of techniques intended to document design decisions about software. This contrasts with systems engineering approaches such as for exampleStatemate and the Yourdon Systems Method (YSM), in which the design of an entire system consisting of software and hardware can be documented. The difference between the system- and the software level is reflected in differences between execution semantics as well as in methodology. In this paper, I show how the UML can be used as a system-level design technique. I give a conceptual framework for engineering design that accommodates the system- as well as the software level and show how techniques from the UML and YSM can be classified within this framework, and how this allows a coherent use of these techniques in a system engineering approach. These ideas are illustrated by a case study in which software for a compact dynamic bus station is designed. Finally, I discuss the consequences of this approach for a semantics of UML constructs that would be appropriate for system-level design

Specification and verification challenges for sequential object-oriented programs

The state of knowledge in how to specify sequential programs in object-oriented languages such as Java and C# and the state of the art in automated verification tools for such programs have made measurable progress in the last several years. This paper describes several remaining challenges and approaches to their solution

Algebraic specification of documents

According to recent research, nearly 95 percent of a corporate information is stored in documents. Further studies indicate that companies spent between 6 and 10 percent of their gross revenues printing and distributing documents in several ways: web and cdrom publishing, database storage and retrieval and printing. In this context documents exist in some different formats, from pure ascii files to internal database or text processor formats. It is clear that document reusability and low-cost maintenance are two important issues in the near future. The majority of available document processors is purpose-oriented, reducing the necessary flexibility and reusability of documents. Some waste of time arises from adapting the same text to different purposes. For example you may want to have the same document as an article as a set of slides or as a poster; or you can have a dictionnary document producing a book and a list of words for a spell-checker. This conversion could be done automatically from the first version of the document if it complies some standard requirements. The key idea will be to keep a complete separation between syntax and semantics. In this way we produce an abstract description separating conceptual issues from those concerned with the use. This note proposes a few guidelines to build a system to solve the above problem. Such a system should be an algebraic based environment and provide facilities for: - Document type definitions; - Definition of functions over document types; - Document definitions as algebraic terms. This approach (rooted in the tradition of constructive algebraic specification), will allow for homogeneous environment to deal with operations such as merging documents, converting formats, translating documents, extracting different kinds of information (to set up information repositories, data bases, or semantic networks) or portions of documents (as it happens, for instance, in literate programming), and some other actions, not so traditional, like mail reply, or memo production. We intend to use CAMILA (a specification language and prototyping environment developed at Universidade do Minho, by the Computer Science group) to develop the above mentioned system

Building Specifications in the Event-B Institution

This paper describes a formal semantics for the Event-B specification language using the theory of institutions. We define an institution for Event-B, EVT, and prove that it meets the validity requirements for satisfaction preservation and model amalgamation. We also present a series of functions that show how the constructs of the Event-B specification language can be mapped into our institution. Our semantics sheds new light on the structure of the Event-B language, allowing us to clearly delineate three constituent sub-languages: the superstructure, infrastructure and mathematical languages. One of the principal goals of our semantics is to provide access to the generic modularisation constructs available in institutions, including specification-building operators for parameterisation and refinement. We demonstrate how these features subsume and enhance the corresponding features already present in Event-B through a detailed study of their use in a worked example. We have implemented our approach via a parser and translator for Event-B specifications, EBtoEVT, which also provides a gateway to the Hets toolkit for heterogeneous specification.Comment: 54 pages, 25 figure

Unified modelling of aerospace systems: a bond graph approach

Systems Integration is widely accepted as the basis for improving the efficiency and performance of many engineering products. The aim is to build a unified optimised system not a collection of subsystems that are combined in some ad hoc manner. This moves traditional design boundaries and, in so doing, enables a structured evolution from an integrated system concept to an integrated system product. It is recognised that the inherent complexity cannot be handled effectively without mathematical modelling. The problem is not so much the large number of components but rather the very large number of functional interfaces that result. The costs involved are high and, if the claims of improved efficiency and performance are to be affordable (or even achievable), predictive modelling and analysis will play a major role in reducing risk. A modelling framework is required which can support integrated system development from concept through to certification. This means building a 'system' inside a computer and demonstrating the feasibility of an entire development cycle. The objective is to provide complete coverage of system functionality so as to gain confidence in the design before becoming locked into a full development programme with associated capital investment and contractual arrangements. With these points in mind the purpose of this thesis is threefold. First, to demonstrate the application of bond graphs as a unified modelling framework for aerospace systems. Second, to review the main principles involved with the modelling of engineering systems and to justify the selection of the bond graph notation as a suitable means of representing the power flow (i.e. the dynamics) of physical systems. Third, to present an exposition of the bond graph method and to evolve it into a versatile notation for integrated systems. The originality of the work is based on the recognition that systems integration is a relatively new field of interest without a mature body of academic literature or reported research. Apparently, there is no open literature on the modelling of complete air vehicles plus their embedded vehicle systems which deals with issues of integrated dynamics and control. To this end, bond graph concepts need to be developed and extended in new direction in order to facilitate an intuitive approach to the modelling of integrated systems