摘要:

The emphasis of data organisation on the specification, design and implementation of large systems raises the question whether data abstraction may be applied to programming languages designed before the widespread use of such techniques. The data abstraction facilities available in FORTRAN 77 are considered, and it is shown that encapsulation is possible for simple data structures. An abstract array data structure is pecified and further refined to allow the definition of iterators. An example of this structure is implemented in FORTRAN 77. The introduction of a series of abstractions is thus made possible, which facilitates structured development and efficient maintenance.

DOI:10.1049/sej.1990.0017

出版商:IEE    

年代:1990

数据来源: IET

摘要:

Although a great deal of research has been carried out in the field of distributed computing, a relatively small fraction of the work has concentrated on the area of distributed applicaitons. This paper is an account of one attempt to explore some of the problems which arise in actually implementing a substantial distributed application; in this case the board game Scrabble. Particular emphasis is placed on continunity, i.e. the ability of the applicaion to continue executing despite partial failure. Our main conclusion from this experience is that much better support should be provided at both the operating system and programming environment level to handle the development and debugging of reliable distributed applications. A number of suggestions are made as to how this can be achieved.

DOI:10.1049/sej.1990.0018

出版商:IEE    

年代:1990

数据来源: IET

摘要:

The state dependency diagram (SDD) is presented as an improved model for entity life history states. Entity life histories (ELHs) are used in methods like SSADM*and LSDM**as a means of establishing the stages each entity occurrence goes through in its life, such as creation, deletion etc. However, ELHs are limited to describing states within one entity, whereas the state dependency diagram shows interdepencies between the states of different entities. Once drawn, the state dependency diagram becomes a model whihc can be used for subsequent analysis.

DOI:10.1049/sej.1990.0019

出版商:IEE    

年代:1990

数据来源: IET

摘要:

This paper describes how a combination of CSP and theme toomethod of software design can be used to formalise the early stages of the object-oriented development of embedded systems, including those with time constraints. Using the example of the watchdog timer, we show how a specification can be developed, exercised in a prototyping environment and then transformed into an outline concurrent Ada program.

DOI:10.1049/sej.1990.0020

出版商:IEE    

年代:1990

数据来源: IET

摘要:

One of the major barriers to the introduction of reuse technology into the software development process is the absence of large repositories of reusable components from which manufacturers can build new generations of systems [1,2]. Owing to the tremendous investment that has been made in developing systems, companies use an evolutionary approach to software development whereby the old software development whereby the old version becomes the basis of the next generation. Owing to such costs, companies are understandably reluctant to develop completely new versions from scratch. If software reusability is to emerge as a discipline, then some mechanism whereby components are reclaimed from existing systems and transformed according to reuse cirteria must be found. This paper discusses an approach designed to reclaim software components from existing systems and transform them into objects, which we contend are inherently more reusable.

DOI:10.1049/sej.1990.0021

出版商:IEE    

年代:1990

数据来源: IET

摘要:

Advances in computing technology have often been geared towards providing individuals with enhanced computing environments. However, in industry it is more common to find large teams of personnel working together towards a common goal. This is particularly the case in the software industry. Hence, the provision of software engineering environments is now seen as a major task facing computing. This paper focuses on the design of an infrastructure (called Cosmos)to support software engineering environments. This infrastructure is carefully tailored to support the functionality required of a software engineering environment. Furthermore, the infrastructure assumes a distributed environment and implements mechanisms to make this distribution transparent to the user. The Cosmos system is unusual in that it combines elements of a functional system with elements of an object-oriented system. It is argued that the two views of data can be synthesis is ideally suited to supporting software engineering environments and handling distribution in an elegant manner.

DOI:10.1049/sej.1990.0022

出版商:IEE    

年代:1990

数据来源: IET