摘要:

AbstractObject‐oriented database systems are designed to meet the requirements of advanced database applications such as computer‐integrated manufacturing. These requirements may evolve in the course of time and may require the migration of the database application from one object‐oriented database system to another. Traditional migration approaches for relational database systems fail when applied to object‐oriented database systems. The goal of this paper is to fill this gap. The paper describes a framework for the migration of object‐oriented database applications. Our approach is based on a detailed analysis of the involved database systems, of the application's database requirements, and of the resources available for the database migration. We illustrate our framework by means of a case study, which is migrating an electronic planning board system from the object‐oriented database system ONTOS to

ISSN:0038-0644    

DOI:10.1002/spe.4380251002

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractWe present a compression technique for heterogeneous files, those files which contain multiple types of data such as text, images, binary, audio, or animation. The system uses statistical methods to determine the best algorithm to use in compressing each block of data in a file (possibly a different algorithm for each block). The file is then compressed by applying the appropriate algorithm to each block. We obtain better savings than possible by using a single algorithm for compressing the file. The implementation of a working version of this heterogeneous compressor is described, along with examples of its value toward improving compression both in theoretical and applied contexts. We compare our results with those obtained using four commercially available compression programs, PKZIP, Unix compress,Stufflt, andCompact Pro, and show that our system provides better space savings.

ISSN:0038-0644    

DOI:10.1002/spe.4380251003

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe paper describes in detail the implementation of INMON, a prototype monitor for recording and displaying interaction networks. Theinteraction networkis designed to show the interrelationships between significant events that occur during the processing of an interaction on a loosely‐coupled distributed system. By being directed at analysing what happens in an interaction, this approach is fundamentally different from other graphical representations that show what happens during the execution of a single program on a distributed system. Examples are given of interaction networks recorded by INMON. The approach is based on very general models of a distributed system and of an interaction, and could be widely applied. We conclude by summarizing what is needed to provide facilities within any operating system for recording interaction network

ISSN:0038-0644    

DOI:10.1002/spe.4380251004

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractSemaphores have been used extensively in programming concurrent tasks. Various extensions have been proposed for problems in which traditional semaphores turned out to be difficult to use. The extended semaphore primitives investigated here are based on the version of semaphores implemented in UNIX System V. Implementation issues are discussed and practical illustrations of their use are provided. In particular, algorithms for a variety of common process scheduling schemes are shown. These solutions are evaluated and the strengths and weaknesses of UNIX semaphores are discussed.

ISSN:0038-0644    

DOI:10.1002/spe.4380251005

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe maintenance of a software system requires a tool for impact analysis and the propagation of change. This paper presents a knowledge‐based model for both. This model is generic because it is not based on any language or design method. Therefore, it can be applied on the basis of ‘problem’ to be solved. It also captures four life‐cycle phases:requirement, specification, designandprogramming. We also provide a domain‐specific view that allows the dependency analysis offine‐grainobjects. Two kinds of dependencies are identified:inter‐phase dependencies, these are dependency relations between the objects of the one phase and another; andintra‐phase dependencies, these are dependency relations between the objects of the same phase. In order to validate this model, we also present a prototype based on two life‐cycle phases:des

ISSN:0038-0644    

DOI:10.1002/spe.4380251006

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

ISSN:0038-0644    

DOI:10.1002/spe.4380251001

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY