面向对象数据库死锁检测方法研究

本文根据面向对象数据库系统中嵌套事务的新的执行特性，提出了一种检测死锁的算法——扩充的边追踪算法，并在一个面向对象数据库原型系统ＭＩＤＳ中予以实现.     

并行对象调度策略

从并行系统的软件设计模式出发,结合面向对象的思想,阐述了在并行系统中以对象为中心进行任务调度的策略.给出了一种具体的算法并简要地分析了该算法的性能.     

基于PVM的C++对象分布并行机制的初步研究

对象具有内在的并行性.将面向对象程序设计与分布并行处理相结合,可产生既具有面向对象特征,又充分利用资源,还可缩短作业运行时间的对象分布并行系统.提出了一种基于PVM(parallelvirtualmachine)的C++对象的分布并行机制.该机制以协议和pvmlib作了向后兼容扩充的PVM系统为对象分布并行支撑;用预处理器将用户作业的并行类分离,并派遣到(PVM)系统中的目标机进行异地编译、加载执行;通过把并行类映射为PVM任务,请求对象消息映射为请求PVM任务消息来实现并行类对象的分布并行.实验结果表明,此对象分布并行机制(当问题规模达到一定程度时)可提高系统资源利用率和程序运行效率,并能简化PVM应用编程.     

一个基于机群系统的面向对象并行程序 开发环境的研究与实现

面向对象程序设计技术可以降低并行程序设计的复杂性,提高并行程序的可读性、可维护性、可移植性.因此提供面向对象的并行程序设计环境,可以减少并行程序开发难度,有效地利用并行计算机系统的潜能.可扩展并行机群系统是随着网络技术迅速发展而出现的一种网络并行计算系统.其主要特点是适于粗粒度任务并行,适于采用消息传递机制.文中在可扩展机群系统上实现了面向对象的并行程序开发环境ParaObject,它由对象平台、并行对象和邮件对象组成,并行程序以并行对象为单位并行执行,通过邮件对象传送数据,具有良好的封装性和可移植性,友好的用户编程接口,使用方便.     

机械设计并行式多专家系统的研制

提出了一种用于机械产品设计的并行式多专家系统（MES）理论模型，并以液压缸智能CAD系统为例给出了并行式MES面向对象框架知识表示、编译和推理的原理和方法。     

一个基于面向对象方法的并行黑板系统的设计

本文论述了用面向对象的系统分析与设计方法和面向对象的编程技术构造大型、复杂的并行黑板实时控制系统的思想和方法。文章以四辊冷连轧机为对象给出了一个设计实例并给出了一个通用的实时控制并行黑板结构ＲＴＣＢ。贯穿全文的一个很重要的思想就是要致力于开发面向对象方法和黑板模型的潜在的并行、并发特性以及所构造系统的可扩充性和易维护性。     

基于数据集约束的并行数据流建模与描述研究

为了简化带有数据集约束的抽象网格工作流语言(AGWL)的工作流建立过程,提出了一种基于扩展面向对象Petri网(DOPN)建模并行数据流的方法.研究了AGWL并行数据流的特点,在此基础上对面向对象Petri网进行扩展,设计了基于扩展面向对象Petri网描述的并行数据流模型,之后定义一套从DOPN到AGWL的映射规则.最后通过一个应用实例对一个带有数据集约束的数据流建立DOPN描述,并生成AGWL数据流代码.该方法简化了AGWL工作流建立过程,并保留了流程验证和仿真的扩展性.     

一种面向对象程序系统的有效测试方法

针对面向对象的程序系统提出了一种集成测试的有效方法。描述了如何从面向对象的系统设计中生成一个测试模型，对模型图正规化并做进一步分解，根据优化后的结果运用并行测试的思想指导系统的集成测试，以期在尽量少的测试开销基础上加快软件测试的进程。     

一个基于机群系统的面向对象并行程序开发环境的研究与实现

面向对象程序设计技术可以降低并行程序设计的复杂性、提高并行程序的可读性,可维护性、可移植性,因此提供面向对象的并行程序设计环境,可以减少并行程序开发难度,有效地利用并行计算机系统的潜能,可扩展并行机群系统是随着网络技术迅速发展而出现的一种网络并行计算系统,其主要特点是适于粗糙度任务并行,适于采用消化传递机制,文中在可扩展机群系统上实现了面向对象的并行程序开发环境ＰａｒａＯｂｊｃｃｔ,它由对象平台,     

一种并发面向对象同步模型研究

同步是并发语言的一个重要特征,然而在面向对象的框架下,同步约束的存在可能导致不期望的方法的重定义.基于并发面向对象规约语言VDM++(Vienna development method)的两种同步机制,提出一种适合于并发面向对象广谱规约语言的同步模型-卫式路径结构.它不但可以支持一般代码的复用,而且可以全方位地支持对同步代码的复用.     

Developing parallel object-oriented programs in the framework of VDM

After surveying the rely-guarantee and some related approaches to extending VDM to develop parallel programs, two main problems are found. One problem is that all explorations of parallelism are done in the stage of operation decomposition or afterwards so that the degree of parallelism is restricted. Another problem is that the atomicity is fixed at one level and the development complexity can not be controlled effectively because there is no natural means to let the level of granularity be under flexible control of the designer. In order to solve these two problems, we introduce a new concept — data decomposition which is based on the ideas of model split, modularisation and operation decomposition, and combine it with VDM to form a more general formal development method DD-VDM, in which some kind of operation decompositions, i.e., operation split can be done before some data reifications. Then a nested parallel object-oriented structure is proposed. Combining these ideas into the unified framework, this paper presents a hierarchical object-oriented design methodology in which two kinds of parallelism, that is, internal parallelism and service parallelism, can be exploited gradually and a kind of virtual atomicity is provided.This research is partially supported by China's National Foundation for Excellent Young Scientists.     

Developing ada programs using the vienna development method (VDM)

A method is presented for the systematic development of sequential Ada programs using the Vienna Development Method (VDM). The approach is based upon using the facilities of Ada for supporting parameterized abstract data types to implement the primitives of the VDM specification language. More experimental work is required to assess the utility of the method, but a systematic approach is promised for using features of Ada unfamiliar to most programmers (e.g. packages, generics and exceptions). Familiarity with Ada is assumed. An overview of VDM is presented so that unfamiliar readers can understand the example given in the paper.     

Informal and formal requirements specification languages: bridgingthe gap

The differences between informal and formal requirements specification languages are noted, and the issue of bridging the gap between them is discussed. Using structured analysis (SA) and the Vienna development method (VDM) as surrogates for informal and formal languages, respectively, two approaches are presented for integrating the two. The first approach uses the SA model of a system to guide the analyst's understanding of the system and the development of the VDM specifications. The second approach proposes a rule-based method for generating VDM specifications from a set of corresponding SA specifications. The two approaches are illustrated through a simplified payroll system case. The issues that emerge from the use of the two approaches are reported     

The formal semantics of ISO VDM-SL

This paper provides an overview of the formal semantics of VDM-SL which currently is being standardized by ISO. This is a specification language used in the formal method known as the Vienna Development Method (or simply VDM). In this paper we will focus on the foundations and the semantics of a rather unique combination of looseness and recursion.     

A VDM case study in mural

The application of an interactive theorem-proving assistant and specification support tool called mural in the specification and verification of a small Vienna development method (VDM) development is described. It is the authors' intention to give a feel for how mural works and of mural's applicability as a tool in specifying and verifying software     

The Rigorous Development of a System Version Control Program

A rigorous approach to software development is followed in developing a program to control the various components and versions of systems. This particular approach to systematic program development is known as the Vienna Development Method (VDM). This paper documerits the author's early experiences with VDM on a small, yet nontrivial, application. The functional specification of the version control system is presented in detail. Design decisions taken for a prototype implementation are also included. The version control program developed is based upon the Gandalf System Version Control Environment of Carnegie-Mellon University. Both that system and the subject of this case study support the most common forms of component interdependency relations, and methods of system evolution.     

基于嵌套循环分类的并行识别技术

传统的分布存储并行编译系统大多是在共享存储并行编译系统的基础上开发的.共享存储并行编译系统的并行识别技术适合OpenMP代码生成,实现方式是将所有嵌套循环都按照相同的识别方法进行处理,用于分布存储并行编译系统必然会导致无法高效发掘程序的并行性.分布存储并行编译系统应根据嵌套循环结构的特点进行分类处理,提出适合MPI代码生成的并行识别技术.为解决上述问题,根据嵌套循环的结构和MPI并行程序的特点,提出了一种新的嵌套循环分类方法,并针对不同的嵌套循环分别提出了相应的并行识别技术.实验结果表明,与采用传统并行识别技术的分布存储并行编译系统相比,按照所提方法对嵌套循环进行分类,采用相应并行识别技术的编译系统能够更高效地识别基准程序中的并行循环,自动生成的MPI并行代码其性能加速比提高了20%以上.     

Parallel Execution of Nested Parallel Expressions

This paper describes an implementation of P L for a massively parallel SIMD machine, the M P MP-1. The system is based on a byte code interpreter which can emulate as many virtual processors on each physical processor as desired (within the limits of memory). The implementation makes it possible to activate more virtual processors once execution has begun and this feature can be used to support nested parallelism. Nested parallelism describes the ability to nest data parallel constructs, a feature of P L , C M L , and N ; however, the outer parallel forms usually have to be sequentialized, with only the innermost forms being executed in parallel. N and a subset of P L have been implemented to fully support nested parallelism by flattening nested structures at compile time. To do this the languages must impose various restrictions on both the data and control structures. There is an overhead associated with the runtime technique described here, but it is very versatile and can execute code in parallel that cannot be “flattened.” Hence this technique can be used to effectively support many of the moredifficultaspects of P L .