摘要:

The paper examines the contribution that a standard programming language can make to the quality of the software written in that language. By means of an example, we show that there is a substantial difference in languages and their implementations in the assurance provided of the correctness of the resulting program. Demonstrating that a program is correct with respect to the semantics of the language is a useful step in quality assurance.

DOI:10.1049/sej.1994.0002

出版商:IEE    

年代:1994

数据来源: IET

摘要:

In this paper, we investigate a scheduling problem in loosely coupled multiprocessor systems. This problem has been addressed by many researchers because it has a substantial effect on the performance of multiprocessor systems. Previous work considered only one class of tasks to be scheduled. In this paper, we propose an algorithm to schedule two classes of tasks, indivisible and divisible tasks, among the available processors in the system. The objective is to find the best scheduling that gives a minimum finish time. The divisible class of tasks, considered here for the first time in a scheduling algorithm, has important applications in signal-processing, image-processing and Kalman filtering. The proposed algorithm answered many important questions that arise when the two classes of divisible and indivisible tasks are considered. Applications of the algorithm include all operating systems with multiprocessor support, such as the Mach operating system. Although two classes of tasks are considered, the complexity of the algorithm stays in a reasonable order.

DOI:10.1049/sej.1994.0003

出版商:IEE    

年代:1994

数据来源: IET

摘要:

For several years, software engineers have debated the impact that inheritance mechanisms have on software development. Inheritance can be ignored until coding begins, or it can be used early during analysis to model conceptual abstractions; specifically, IS_A relations between classes in a problem domain. Unfortunately, the conceptual structuring relevant to analysis can conflict with the practice of code reuse. In this paper, we explain why this conflict arises and suggest ways of dealing with it. We review the basic facilities provided by inheritance mechanisms in object-oriented programming languages and survey their use in programming. Legitimations for the use of inheritance are described and evaluated. We conclude with a tentative proposal for the development of more powerful inheritance mechanisms.

DOI:10.1049/sej.1994.0004

出版商:IEE    

年代:1994

数据来源: IET

摘要:

The paper develops three inter-related ideas; that a ‘well structured’ software system may be understood as a compressed representation of its inputs and its outputs; that software design may be seen as a process of information compression; and that the execution of software may also be understood as a process of information compression. Information compression may be achieved by the comparison or matching of patterns, the merging or unification of patterns which are the same, and a search through the space of possible unifications to find the set or sets giving the most compression. A prototype has been developed for a ‘new generation’ computing system dedicated to information compression by pattern matching, unification and search. Examples from the prototype are presented to illustrate the themes. These ideas can mean increased efficiency in software development and increased quality in the resulting product. Planned developments of the ideas are briefly described.

DOI:10.1049/sej.1994.0005

出版商:IEE    

年代:1994

数据来源: IET