An efficient and flexible C++ library for concurrent programming

A major problem for the integration of concurrency in object-oriented languages is the so-called inheritance anomaly, i.e. the conflicts between inheritance and concurrency that often cause the need to redefine inherited methods in order to maintain the integrity of objects. Several solutions have been proposed for resolving these conflicts. However, some of them are incomplete, and do not solve all types of inheritance anomaly; others make the definition of classes complex and/or their implementation inefficient. This paper describes a C⁺⁺ library for concurrent programming that provides a comprehensive framework particularly suitable for coarse-grained distributed applications. This library copes with the inheritance anomaly problem, presenting a solution that minimizes the redefinition of inherited methods without increasing the complexity to write them. This solution is based on the use of a special set of methods, called interface methods, composed of a body and two sets of synchronization constraints. These two sets of synchronization constraints are respectively used to enable the execution of their method body and to disable the methods that cannot be executed after their method. © 1998 John Wiley & Sons, Ltd.     

A Concurrent,Distributed Architecture for Diagnostic Reasoning

This paper demonstrates the feasibility of modeling concurrent diagnostic reasoning (CDR) by means of the computational model of actors. Actors have a value added on top of objects, because they include the properties of abstraction, modularity and reuse of objects but allow really concurrent and distributed architectures, in the sense that memory (the environment) is assumed not to be shared among actors. Whether concurrency really implies efficiency is still debated. We are more concerned here with the actor-based design of the diagnostic reasoning model. As a testimony of the feasibility of our proposal, a concrete, actor-based diagnostic program is presented as a module for an Intelligent Tutoring System in the domain of school algebra. CDR is obtained from the coordinated behaviour of actors which possess limited local knowledge and accomplish the global goal of diagnostic reasoning by interacting with each other. We examine how the traditional approaches to student modeling, such as overlay and bug models, can be re-visited in a distributed perspective of computational actors and how the latter view outperforms the previous ones.     

Modeling Biological Systems in Stochastic Concurrent Constraint Programming

We present an application of stochastic Concurrent Constraint Programming (sCCP) for modeling biological systems. We provide a library of sCCP processes that can be used to describe straightforwardly biological networks. In the meanwhile, we show that sCCP proves to be a general and extensible framework, allowing to describe a wide class of dynamical behaviours and kinetic laws.     

Concurrent programming in VISO

Concurrent programming is more difficult to use and understand than sequential programming. In order to simplify this type of programming a number of approaches have been developed such as visual programming. Visual Occam (VISO) is a visual programming language for concurrent programming. It has a graphical syntax based on the language Occam and its semantics is represented both in petri net and process calculus. This paper presents a modular visual approach to write concurrent programs using the VISO language. Concurrent programs in VISO are specified graphically at different levels of abstraction. This paper describes this modular visual approach by constructing two examples in VISO. The first example is a simple concurrent program and it is mainly used to show the details of constructing a concurrent program in VISO. The second example is a larger concurrent program with more levels of abstraction. Copyright © 2000 John Wiley & Sons, Ltd.     

Evaluating the Expressive Power of the Real-Time Specification for Java*

The goal of this paper is to evaluate the real-time specification for Java proposal by performing several case studies. These case studies include: an extensible general resource controller; atomic action support infrastructure; unbounded and imprecise computations. They have been used previously by the Ada community to evaluate the efficacy of the Ada concurrency and real-time models. Our results indicate that the Real-Time Specification for Java is expressive enough to cope with the demands of real-time concurrent programming. If it can be implemented efficiently, it will provide an alternative to Ada 95 for programming real-time systems.     

论交叠式并发控制系统

建立了交叠式并发控制系统的理论基础,把整个控制系统建立在交叠式并发(存储对象控制)的计算机体系结构之上,整个控制系统需要这种计算机的硬件、操作系统和编译系统的支持。首先,用对象作为主线索贯穿交叠式并发控制系统的组成方式、运行过程和开发过程。一个交叠式并发控制系统由一些对象组合而成;另外,外部环境中任何一个控制单元及其所附带的(异常)消息可以随时启动相应的某个对象的方法执行,这样就可能出现几个对象的方法交叠地并发执行;最后,它的设计过程是先进行总体设计,按功能和接口分解出一个个对象,然后利用编译系统随时往计算机中添加(生成)任意一个对象。     

程序切片技术在并发程序模型检查中的应用

模型检查技术在硬件和协议设计方面已经取得很大成功,但在软件验证方面仍存在很多困难。其主要问题是如何从源代码中自动抽取验证所要模型并精简其状态空间。文中通过对程序切片技术的研究,来解决并发程序验证的建模问题,包括把验证公式映射到切片准则．并把得到的程序切片转化为验证所需的模型。经程序切片处理后,软件模型检查效率得到提高。     

A Systematic Approach to the Petri Net Based Specification of Concurrent Systems

We describe an approach to the specification of concurrent systems which enables a Petri net model of a system to be built up in a systematic way starting from a trace-based CSP specification. This method enables the separate specification of the behavior of each component (process) and their interactions in terms of the feasible sequences of events in which they can be involved. A set of rules is then applied to transform the trace-based specifications into a complete Petri net that is analyzed and/or executed to validate system behavior. The domain transformation procedure is fully automatable. The specification of a safety-critical railway control system is used as a case study.     

Synchronous/Reactive Programming of Concurrent System Software

Synchronous languages are intended for programming reactive systems. Reactive systems, which include real-time systems and key operating system components, interact continually with their environment. This paper considers the applicability of imperative synchronous/reactive languages to the development of general system software, that is, to the implementation of operating system kernels, file systems, databases, networks, server architectures, device drivers, etc. The languages Esterel and Reactive C (RC) receive special attention as Esterel is the oldest and most developed such language and RC is specifically designed for compatibility with C systems programming. An alternative soft-instruction software architecture is described, which is well suited to real-world system programming. © 1997 by John Wiley & Sons, Ltd.     

并发软件的图形化设计方法研究(一):并发设计语言CONDL的定义

这项研究的目标是：为并发软件的设计提供一种图形化的方法和支撑工具,以便用图形表过并发软件的设计,并生成并发程序的框架（并发程序单元的划分和它们之间的通信）,这样做的好处在于提高软件的生产率,改善软件质量,在论文的这一部分,给出了并发设计语言CONDL的定义。     

并发代码的继承问题

文献[1]提出了一种新的刻划并发行为的方法.本文继续讨论这种方法在面向对象的程序设计中是如何解决并发代码在继承过程中的冲突问题的.     

大量并发用户访问控制技术研究

为了应对网络用户规模的急剧增长,不断的改善网络硬件设备以及软件的性能。但是,仍然不能提供令用户满意的服务。主要研究了在大量并发用户存在的情况下如何应用通信代理技术、数据库连接池、集群技术改善数据库服务器的性能,为用户提供正常的网络服务。     

面向并行设计的智能决策支持系统研究

基于并行设计支撑环境讨论了智能决策支持系统的重要性,论述了基于知识的并行设计过程和基于小循环的并行设计过程模型,建立了复杂产品并行智能决策支持框架,阐明了适合并行设计智能决策支持系统的领域知识描述模型,并以方案设计智能决策支持系统为例进行了验证。     

并发面向对象程序设计语言研究与进展

随着面向对象程序设计的普及和对并发应用程序需求的增加，并发面向对象程序设计语言的设计日益成为研究热点。     

Procedure-Level Verification of Real-time Concurrent Systems

We want to develop verification techniques for real-time concurrent system specifications with high-level behavior structures. This work identifies two common engineering guidelines respected in the development of real-world software projects, structured programming and local autonomy in concurrent systems, and experiments with special verification algorithm based on those engineering wisdoms. The algorithm we have adopted respects the integrity of program structures, treats each procedure as an entity instead of as a group of statements, allows local state space search to exploit the local autonomy in concurrent systems without calculating the Cartesian products of local state spaces, and derives from each procedure declaration characteristic information which can be utilized in the verification process anywhere the procedure is invoked. We have endeavored to implement our idea, test it against an abstract extension of a real-world protocol in a mobile communication environment, and report the data.     

基于对象的并发模型

为了研究和发展分布式人工智能,探讨一种新的计算模型,利用面向对象技术提出了一个基于对象的并发模型（OBCM）。讨论了它的两种通讯机制,即同步和异步通讯方式,异步通讯方式又分为过去型消息传递和将来型消息传递,而同步通讯方式则包括现在型消息传递和等待方式。证明了它们可归约为过去型消息传递和等待状态。另外,OBCM为了增强其表达能力,提供了响应目的地机制。在OBCM中,对象的独立自治特点对模拟分布式问题求解尤为适用。最后以一个分布式问题求解的具体实例说明了OBCM的思想。     

A Robust Method for the Concurrent Motion Planning of Multi-Manipulators Systems

In this article a robust and simple procedure for the on-line concurrent motion planning of multi-manipulators is presented. The approach is based on solving for each manipulator a linear system of equations taking into account a vector for motion planning, and an original scheme for the appropriate perturbation of the pseudoinverse matrix. This method can pursue simultaneously both motion coordination and singularities prevention in real time in a sensor based environment. These properties make it suitable for fully autonomous or telerobotic systems operations.     

Observable Behavior of Dynamic Systems: Component Reasoning for Concurrent Objects

Current object-oriented approaches to distributed programs may be criticized in several respects. First, method calls are generally synchronous, which leads to much waiting in distributed and unstable networks. Second, the common model of thread concurrency makes reasoning about program behavior very challenging. Models based on concurrent objects communicating by asynchronous method calls, have been proposed to combine object orientation and distribution in a more satisfactory way. In this paper, a high-level language and proof system are developed for such a model, emphasizing simplicity and modularity. In particular, the proof system is used to derive external specifications of observable behavior for objects, encapsulating their state. A simple and compositional proof system is paramount to allow verification of real programs. The proposed proof rules are derived from the Hoare rules of a standard sequential language by a semantic encoding preserving soundness and relative completeness. Thus, the paper demonstrates that these models not only address the first criticism above, but also the second.