基于进程代数规约生成软件体系结构模型的方法

需求规约到软件体系结构(SA)模型的转换是软件工程领域的一个研究热点,UML-RT广泛用于实时系统软件体系结构建模,然而基于自然语言规约建立的UML-RT模型往往是不精确的,存在二义性,为了解决这一问题,需要赋予UML-RT模型形式化语义.进程代数是一种用来解决并发系统通信问题的形式化方法,具有精确的语法和语义,并且便于机器自动检验与验证.TCSP是进程代数CSP的实时扩展,适合于规约实时系统带有时间约束的行为.提出一种基于进程代数规约生成SA模型的方法.首先建立了自然语言规约到SA模型的转换框架;然后使用时间通信顺序进程(TCSP)描述实时系统需求规约,通过建立TCSP到UML-RT的转换机制,从而实现进程代数规约到SA模型的转换;最后通过一个实例来验证该方法在实时软件建模过程中的有效性.实验分析表明通过该方法建立的UML-RT模型能够从整体上提高实时系统SA设计的可信性.     

面向嵌入式实时软件的需求规约语言及检测方法

针对嵌入式实时软件需求规约及其检测问题,提出了基于层次并发有穷状态机的可合成的图形化建模语言RTRSM*(real-time requirements specification model*),利用转换有效期和事件预定机制来描述时间限制,能够较好地支持系统交互性和实时性的建模.为弥补RTRSM*作为操作性规约语言不便于性质描述的问题,提出了命题时序逻辑RITL(real-time interval temporal logic).该语言以时间状态序列为语义模型,具有基于区间和时间点的量化时间属性描述功能,能自然、全面地描述RTRSM*模型性质.介绍并讨论了基于两种语言的规约检测方法和技术,主要包括系统状态空间有穷的RTRSM*模型状态可达图的相关问题和规约的模拟执行.     

服务组合的代数规约

现有的服务组合描述途径不能有效地验证和测试组合正确性,针对这一问题,提出了一个代数规约方法,引入规约包机制扩展面向服务代数规约语言SOFIA以支持该方法。用代数规约单元描述服务系统中的各种实体,其中基调部分定义实体的语法和结构,公理部分定义其功能和行为特性。与一个服务相关的规约单元封装在一个包中或拆分在几个相互引用的包中,每个包形成一个命名空间。当多个服务组合在一起时,以这些服务的代数规约包为基础,一方面抽象地定义组合服务的交互过程和语义,形成描述服务组合实现方式的实现规约包;另一方面抽象地定义组合服务对外接口及其功能语义,形成描述组合服务需求的抽象规约包。在实现规约和抽象规约的双元结构基础上,进一步定义了实现规约和抽象规约之间必须满足的“实现”关系,证明了满足实现关系可以保证实现的正确性,从而为服务组合的可验证性和可测试性奠定了理论基础。最后结合实例分析阐述了用代数规约描述服务组合的抽象性、可表达性和可验证性。     

模式驱动的系统安全性设计的验证

随着万维网和移动计算技术的广泛应用,系统安全性得到了越来越多的关注,使用安全模式对系统安全解决方案进行设计并验证是提升系统安全性的一种有效途径。现有方法根据系统安全需求选择适用的安全模式,在此基础上将模式组合为系统的安全解决方案,并通过模型检测方法验证其安全性。但是,这些方法往往将方案看作整体进行验证,忽略了内部安全模式的组合细节,难以在包含大量模式的复杂系统中定位缺陷。提出一种模式驱动的系统安全性设计的验证方法,首先使用代数规约语言SOFIA描述安全模式及其组合,以构建系统安全解决方案的形式化模型;然后将SOFIA规约转换为Alloy规约后,使用模型检测工具验证模式组合的正确性和系统的安全性。案例研究表明,该方法能够有效地验证系统安全解决方案的正确性。     

功能规约自动生成

ＮＤＲＡＳＳ系统是南京大学计算机软件研究所新近研制成的一个由软件需求定义到软件功能规约的转换系统。功能规约自动生成是该系统的主体部分。它涉及状态空间的生成，操作定义的生成和系统总控流程的生成等。本文简要阐述了这些问题，特别讨论了ＮＤＲＡＳＳ系统中控制流图的规范化与结构化分解，全文包括研究动因、ＮＤＲＡＳＳ系统、功能规约自动生成架构、控制流图的规范化和结构化、代码生成、示例以及结语七个部分。     

从BPMN模型导出组合服务的代数规约

针对应用规约自动测试BPEL表示组合服务时需要解决BPEL服务的规约生成问题,提出了一种从BPMN模型导出BPEL规范定义的组合Web服务的由代数规约语言CASOCC-WS表示的代数规约方法。首先,定义从BPMN模型转换成基调的规则和从BPMN结构转换成正则表达式的规则,设计由正则表达式导出构成公理的项的算法;然后,提出根据所得的项人工书写公理的启发式规则;最后,实现一个从BPMN模型导出组合服务基调的工具原型。案例研究表明,该方法可以解决BPEL服务的代数规约生成问题。     

微分代数系统的数值仿真算法

介绍了微分代数系统ＤＡＥ的基本概念及仿真算法,特别指出了用ＢＤＦ方法求解高指标常系数线性ＤＡＥ系统时的数值稳定性缺陷。最后,针对飞行器轨道约束实时控制问题,给出了３阶收敛的代数约束算法。     

形式化构件规约自动生成中的演化转换

基于软件体系结构的开发将是未来大型、复杂软件开发的主要技术,而构件是该方法的基础。形式化构件规约对构件的功能描述、分类和检索有重要意义。文中给出了一种用于形式化构件规约自动生成的转换方法即演化转换,对该方法的转换过程、转换规则提取、表示及主要转换算法进行了详细说明,并对规约的完整性和转换的正确性进行了探讨。最后,还对该方法的实现系统及其特点进行了简要介绍。演化转换能较好地控制转换粒度和跨度,对转换正确性和规约完整性也有一定的保证,在转换过程中实现了规约的垂直重用,使构造的模型和规约对需求变化有一定的适应性。     

代数语言规约的ML原型翻译系统

形式化的规约说明对于提高软件开发的正确性和效率有很大作用,一个形式化的规约说明语言开发环境如图1所示。目前有的原型系统是用常规高级语言,即一般的过程语言来写的,如C。这种原型环境涉及大量低层细节.程序繁琐冗长,且和计算机状态相联系,破坏了原有规约的证明特性。     

基于代数规约的Web服务测试

针对自动测试Web服务,提出基于代数规约测试Web服务的方法,包括描述Web服务的代数规约语言ASOWS。基于Web服务的代数规约,采用方法覆盖准则以及等式覆盖准则自动生成测试用例,在此基础上,设计并实现一个原型工具。结果表明该方法能够自动测试部署在Web应用服务器上的Web服务。     

Hierarchical development of programming languages

The experience in designing large software systems shows that even the definitions of a programming language can be seen as the application of specific implementation and formalization techniques rather than as the result of a «designing art». In this context, a formalism is proposed here as a tool for defining conventional high level programming languages. The formalism is an algebraic model supporting the definition of representational entities such as types. A Type is a set of data and operations on them. An isomorphism between language components and types realizes an isomorphism between the language and its specification on the model. Then, the definition of a language can be performed by stepwise definitions of the types representing the language components. So the model is also a language development tool. Stepwise definition methodologies are also investigated and two are the proposed ones: the horizontal, methodology and the vertical methodology. In particular, the vertical methodology defines languages by the development of a hierarchy of abstraction levels, each corresponding to one class of languages: The last class only contains the language being defined.     

Modular algebraic nets to specify concurrent systems

The authors present the basic features of a specification language for concurrent distributed systems, developed at the Department of Information Sciences of the University of Milan, Italy. The language is based on a class of modular algebraic high-level nets, OBJSA nets, which result from the synthesis of superposed automata (SA) nets and of the algebraic specification language OBJ. It is supported by the OBJSA Net Environment (ONE). OBJSA nets stress the possibility of building the system model by composing its components and encourage the incremental development of the specification and its reusability. An OBJSA net consists of an SA net inscribed with terms of an OBJ module. The ONE environment supports the user in producing and executing a specification, hiding from her/him, as much as possible, the technical details of the algebraic part of the specification. The paper provides a complete presentation of OBJSA nets, including a user-oriented introduction, the definition of OBJSA nets (as subclass of SPEC-inscribed nets), of their occurrence rule (the semantics) and of the composition operation. In addition it presents the kernel of the support environment     

Syntax and semantics of the compositional interchange format for hybrid systems

Different modeling formalisms for timed and hybrid systems exist, each of which addresses a specific set of problems, and has its own set of features. These formalisms and tools can be used in each stage of the embedded systems development, to verify and validate various requirements.The Compositional Interchange Format (CIF), is a formalism based on hybrid automata, which are composed using process algebraic operators. CIF aims to establish interoperability among a wide range of formalisms and tools by means of model transformations and co-simulation, which avoids the need for implementing many bilateral translators.This work presents the syntax and formal semantics of CIF. The semantics is shown to be compositional, and proven to preserve certain algebraic properties, which express our intuition about the behavior of the language operators. In addition we show how CIF operators can be combined to implement widely used constructs present in other timed and hybrid formalisms, and we illustrate the applicability of the formalism by developing several examples.Based on the formal specification of CIF, an Eclipse based simulation environment has been developed. We expect this work to serve as the basis for the formal definition of semantic preserving transformations between various languages for the specification of timed and hybrid systems.     

非线性代数规范的直接实现技术

代数规范是支持软件规格说明和设计的一种有效的方法，代数规范的直接实现技术是该研究领域的一个主要分支，目前这方面的研究基本上局限于线性代数规范，本文介绍一个实现非线性代数规范的转换过程，从该过程可自然是导出针对不同程序设计语言的转换系统，我们已实现了一个基于Ｐａｓｃａｌ语言的转换系统。     

Design of Ada Systems Yielding Reusable Components: An Approach Using Structured Algebraic Specification

Our experience with design of Ada¹ software has indicated that a methodology, based on formal algebra, can be developed which integrates the design and management of reusable components with Ada systems design. The methodology requires the use of a specification language, also based on formal algebra, to extend Ada's expressive power for this purpose. We show that certain requirements for the use of Ada packages which cannot be expressed in Ada can be expressed in algebraic specification languages, and that such specifications can then be implemented in Ada.     

SLAN-4?A Software Specification and Design Language

SLAN-4 (``Software Language-4') was developed to meet the need for a formal tool for specifying and designing large software systems. It provides language constructs for algebraic and axiomatic specifications and also pseudocode constructs for the design step. A major design goal was to ease subsequent refinements of a (given) specification. The design can start with a very informal specification, which can be implemented later using lower level concepts. This paper gives an overview of the SLAN-4 syntax and semantics. It concentrates on the most important aspects of: ? abstract data types, ? algebraic specification of abstract data types, and ? axiomatic specification of modules. Because the pseudocode part of SLAN-4 consists mainly of control structures similar to those in modern high-level programming languages, this element of the language is not separately described. The paper includes an example of how to use SLAN-4, and also the experiences gained in using the language to formally specify a real-world software product of about 18 000 lines of code written in an IBM internal high-level language.     

Visual Specification of Systems with Heterogeneous Coordination Models

In this paper a prototype of a visual specification language called Visual Coordination Diagrams (VCD) for high-level design of concurrent systems with heterogeneous coordination models is presented. The key property of VCD is the separation of behavioral aspects from coordination aspects. We also highlight the heterogeneity of VCD which has two levels. At first, it allows different coordination models to be mixed in a particular specification. Secondly, different formalisms can be incorporated to VCD for specification of behavioral aspects. This paper contains an overview of the language followed with its formal definition. An example of using the language is also given.     

Familial model of data

The family of sets is proposed as the basic structure for modeling data. A family is created by indexing one set of objects by another to represent a directed binary association between two sets. Familial models are shown to have a number of distinct advantages in supporting diverse user views through a hierarchy of abstractions and a variety of derived data, and in describing themselves and other data models through metamodels. An algebra of families is introduced to provide a data definition, maintenance and processing language that is minimal, intuitive, algebraic and theoretically sound. The language is extended to a specification language for database application systems, largely eliminating the need for embedding database constructs into procedural programming languages.