一个半自动生成Ada程序的软件开发环境GFKD-AUTO

本文描述了一个半自动生成Ada程序的软件开发环境GFKD__AUTO的设计与实现。在介绍了设计思想,总体结构和界面情况之后,本文列举了该环境的主要功能,除变换子系统外,该环境还集成了查阅子系统,窗口子系统,编辑子系统(包括正文编辑和图形编辑),编译子系统和文件管理子系统,旨在用来辅助软件开发。变换子系统使用户可通过最少的干预半自动地实现从问题的自然语言描述到Ada程序的变换。     

一个Ada软件开发工具系统的设计与实现

本文通过对Ada/PAD文本的制定原则,以及对PAD文本的具体扩充,PADA系统的设计思想和系统的组织结构,乃至PADA系统的各个部分具体实现的数据结构及表格的详尽阐述,介绍了Ada软件开发工具PADA系统的功能和特点。     

分布计算机系统的程序设计

本文论述分布计算机系统的模块性、并行性和自治性在程序设计上的体现,强调了分布模块和信件传递通信同步机构两个特点。以它们为标志对并发程序设计语言进存的分类表明了分布式程序设计语言的特征和地位。接着讨论信件传递原语中信道互称、同步方式和远方过程调用等问题,最后结合CSP、DP和Ada三种典型语言对进程通信同步机制进行了具体介绍。     

面向分布式对象的一种集成服务报表系统

结合一个分布式网络下报表系统设计实例,提出了基于服务的分布式软件设计思想,采用将报表客户端以及报表服务包装成CORBA对象并通过数据服务与分布式数据源进行通信的方案。并就远程报表系统的设计与实现以及数据服务的具体问题进行了论述,给出了程序流程和设计要点。     

分区间通信在机载计算机系统中的应用研究

在机载计算机系统中不同系统之间的通信是系统集成中需要重点考虑的问题之一.介绍了近年机载计算机系统的发展过程.随着顶层体系架构的发展,随之产生了分区操作系统.在分区操作系统中分区间的通信和传统的通信方式有很多不同.就分区间通信的优点和缺点进行了详细的阐述,最后得出了对分区间通信进行限制的必要性及具体的限制措施.     

X射线单晶衍射仪远程控制系统消息通信系统

为突破现有的X射线单晶衍射仪操作与控制系统上位机直接控制下位机模式,采用RabbitMQ企业级消息队列服务器作为控制通信服务器,并以此为基础搭建X射线单晶衍射仪远程控制系统的消息通信平台,实现对分布式各个子系统的远程操作与控制.本文介绍了针对远程控制系统的消息通信系统进行设计,初步测试表明在此通信系统上能够实现稳定精准的消息通信.     

结构动力数值仿真两级并行计算系统开发及应用

根据分布式存储并行计算机的体系结构特点,设计了一个结构动力数值仿真两级并行计算系统.首先通过两级分区为并行计算准备数据,并将数据分布式存储在各节点的局部存储器上;在结构动力分析过程中,通过进一步缩减问题规模和有效地提高通信效率大幅度减少了界面方程求解时间以及系统求解总时间.文中详细阐述了该系统工作原理、并行计算流程和系统实现的相关软件开发工具.最后通过典型数值算例验证了该系统的有效性.     

基于精化的TrustZone多安全分区建模与形式化验证

TrustZone作为ARM处理器上的可信执行环境技术,为设备上安全敏感的程序和数据提供一个隔离的独立执行环境.然而,可信操作系统与所有可信应用运行在同一个可信环境中,任意组件上的漏洞被利用都会波及系统中的其他组件.虽然ARM提出了S-EL2虚拟化技术,支持在安全世界建立多个隔离分区来缓解这个问题,但实际分区管理器中仍可能存在分区间信息泄漏等安全威胁.当前的分区管理器设计及实现缺乏严格的数学证明来保证隔离分区的安全性.详细研究了ARM TrustZone多隔离分区架构,提出一种基于精化的TrustZone多安全分区建模与安全性分析方法,并基于定理证明器Isabelle/HOL完成了分区管理器的建模和形式化验证.首先,基于逐层精化的方法构建了多安全分区模型RMTEE,使用抽象状态机描述系统运行过程和安全策略要求,建立多安全分区的抽象模型并实例化实现分区管理器的具体模型,遵循FF-A规范在具体模型中实现了事件规约;其次,针对现有分区管理器设计无法满足信息流安全性验证的不足,设计了基于DAC的分区间通信访问控制,并将其应用到TrustZone安全分区管理器的建模与验证中;再次,证明了具体模型...     

可变式分区算法演示程序的设计与实现

可变式分区管理是操作系统存储管理的方法之一.利用Visual Basic语言开发的多媒体动态演示程序,通过在同一界面模拟四种算法的执行,对比了内存分配与回收过程,方便学习者掌握动态分区的基本原理.文中阐述了可变式分区的基本原理、演示软件的整体结构和具体的实现技术.     

切换非线性系统的分布式模型预测控制

针对一类具有预先指定切换序列的切换非线性系统,研究了具有通信信道干扰和时滞测量的分布式模型预测控制问题.在每个子系统都存在镇定控制器的假设下,利用基于Lyapunov函数的模型预测控制器设计了分布式模型预测控制器,并给出了闭环切换非线性系统最终有界的充分条件.最后,通过仿真结果表明了分布式模型预测控制策略的有效性.     

Ada95分布系统模型的分析

本文详细分析了Ada95分布系统模型的语义,重点探讨了分布单元的构成、通信和库单元分类编译指示,最后给出了网络应用的例子。     

Towards complexity metrics for Ada tasking

Using Ada as a representative distributed programming language, the author discusses some ideas on complexity metrics that focus on Ada tasking and rendezvous. Concurrently active rendezvous are claimed to be an important aspect of communication complexity. A Petri net graph model of Ada rendezvous is used to introduce a rendezvous graph, an abstraction that can be useful in viewing and computing effective communication complexity     

A comparative study of task communication in ada

A previous paper compared the mechanisms for process communication in Hoare's communicating sequential processes and in Brinch Hansen's distributed processes, by both qualitative and quantitative analyses. This paper extends these analyses to the corresponding features for communication between tasks in Ada. The similarity between Ada's features and Hoare's proposals is confirmed, but some limitations on non-determinism in Ada are noted.     

A Distributed Real-Time Operating System

A distributed real-time operating system, Fados, has been developed for an embedded multiprocessor system. The operating system is based on a host-target approach and provides for communication between arbitrary processes on host and target machines. The facilities offered are, apart from process communication, access to the file system on the host by programs on the target machine and monitoring and debugging of programs on the target machine from the host. The process communication has been designed in such a way that the possibilities are the same as those offered by the Ada programming language. The operating system is implemented on an MC 68000 based multiprocessor system in combination with a Unix

1 Unix is a trademark of A. T. & T. Bell laboratories.

host.     

On the Implementation and Use of Ada on Fault-Tolerant Distributed Systems

In this paper, we discuss the use of Ada® on distributed systems in which failure of processors has to be tolerated. We assume that tasks are the primary object of distribution, and that communication between tasks on separate processors will take place using the facilities of the Ada language. It would be possible to build a separate set of facilities for communication between processors, and to treat the software on each machine as a separate program. This is unnecessary and undesirable. In addition, the Ada language Reference Manual states specifically that a system consisting of communicating processors with private memories is suitable for executing an Ada program.     

ARTK-M2: A kernel for Ada tasking requirements: An implementation and an automatic generator

A run-time kernel, ARTK-M2, supporting Ada tasking semantics is discussed; full support for task creation, synchronization, communication, scheduling, and termination is provided, together with all options of the Ada rendezvous. An implementation in Modula-2 is presented and a method for automatically translating Ada programs into semantically equivalent Modula-2 programs with corresponding kernel calls is introduced. A parser generator and an attribute grammar were used for the automatic translation. A subset of the Ada Compiler Validation Capability was processed to test the implementation and to illustrate the translation mechanism. The kernel is applicable to the study of real-time control systems; it can also serve as a baseline for studying implementation alternatives of Ada concepts, such as new scheduling algorithms, and for analysing new language constructs. Work is under way to implement some of the changes to the Ada tasking model being proposed as a result of the language revision (Ada9X). Finally, through proper extensions, ARTK-M2 can form an integral part of programming tools such as an Ada compilation system and a distributed kernel for multi-processing environments.     

Experience acquiring and retargeting a portable Ada compiler

A technique for implementing Ada with reasonable effort on a piece of non-standard hardware is described. The target machine is a single processing element in an experimental multiprocessor based on NS32000. A portable Ada front-end compiler was used for retargeting, and the process of acquiring and evaluating the front end is described. Based on this experience, comments on the validation, quality and efficiency of Ada compilers are given, along with a detailed overview of the resultant system. The Ada system was built from scratch on the bare hardware. It has three main components: a code generator, a run-time system and an Ada kernel. The code generator is table driven and generates symbolic NS32000 assembler. This code is then assembled and linked by commercially available components. The run-time system and the kernel are implemented in assembly language and Concurrent Euclid and handle tasking, exceptions and scheduling. The result is a complete Ada implementation.     

构件技术在分布式信息系统中的应用

详细论述构件设计的思想，探讨一种基于构件技术的分布式信息系统开发方法，给出开发模型和具体的开发步骤．设计实现消防文书管理子系统，表明利用构件技术开发分布式信息系统是高质、高效的．     

Remote rendezvous

BNR Pascal is a systems programming language intended for the implementation of the systems software of distributed computing systems. It supports the Ada Rendezvous model of tasking and communication, uniformly extended to support communications between tasks distributed over the computing nodes of a system. BNR Pascal was designed and implemented in 1980, and has since been used to implement the operating systems and real-time applications software for Northern Telecom's Meridian family of products. In total, more than 2 million lines of BNR Pascal exist. This paper describes the BNR Pascal remote rendezvous: the extension of rendezvous to interprocessor communication. It discusses the implementation of remote rendezvous, describing the advantages and disadvantages of several options. Finally, it details BNR's experience in using remote rendezvous in building substantial, practical distributed systems used in products.     

电网调度自动化系统中IEC104传输规约如何实现信息交换的网络化

在电网调度自动化系统中,通信子系统应用IEC60870-5-104传输规约,通过TCP/IP网络访问进行数据传输,实现了变电站信息交换的网络化。分析了报文传输与产生时延的过程,给出了处理技术措施,保证传输的实时性。