A safety shell for UML-RT projects structure and methods of the corresponding UML pattern

A safety shell pattern was defined based on a re-configuration management pattern and inspired by the architectural specifications in Specification PEARL. It is meant to be used for real-time applications to be developed with UML-RT as described. The implementation of the safety shell features as defined in Kornecki and Zalewski (Software Development for Real-Time Safety—Critical Applications. Software Engineering Workshop—Tutorial Notes, 29th Annual IEEE/NASA 03, pp 1–95, 2005), namely, its timing and state guards as well as I/O protection and exception handling mechanisms, is explained. The pattern is parameterised by defining the properties of its components as well as by defining the mapping between software and hardware architectures. Initial and alternative execution scenarios as well as the method for switching between them are defined. The goal pursued with the safety shell is to obtain clearly specified operation scenarios with well-defined transitions between them. To achieve safe and timely operation, the pattern must provide safety shell mechanisms for an application designed, i.e., enable its predictable deterministic and temporally predictable operation now and in the future.     

A method for describing the syntax and semantics of UML statecharts

In this article we present a method for describing the language of UML statecharts. Statecharts are syntactically defined as attributed graphs, with well-formedness rules specified by a set of first-order predicates over the abstract syntax of the graphs. The dynamic semantics of statecharts is defined by Abstract State Machines parameterized with syntactically-correct attributed graphs. The presented approach covers many important constructs of UML statecharts, including internal, completion, interlevel and compound transitions as well as history pseudostates. It also contains strategies to handle state entry/exit actions, state activities, synch states and choice pseudostates.     

基于UML和Petri网的铁路联锁软件建模

在异种嵌入式平台上，采用统一建模语言UML，可为铁路联锁软件建立平台无关模型，从而改进软件的开发和复用。UML适用于软件的静态结构和简单场景下的动态行为的建模。为保证其安全性，采用了Petri网作为补充，对复杂的动态行为和约束规则，在模型中加入了精确和严格的形式化描述。     

Towards an Integrated Graph Based Semantics for UML

Recently, we proposed an integrated formal semantics based on graph transformation for central aspects of UML class, object and state diagrams. In this paper, we explain the basic ideas of that approach and show how two more UML diagram types, sequence and collaboration diagrams, can be captured. For UML models consisting of a class diagram and particular state diagrams, a graph transformation system can be defined. Its graphs are associated with system states and its rules with operations in the class diagram and transitions in the state diagrams. Sequence and collaboration diagrams then characterize sequences of operation applications and therefore sequences of transformation rule applications. Thus valid sequence and collaboration diagrams correspond to derivations induced by the graph transformation system. Proceeding this way, it can be checked for example whether such an operation application sequence may be applied in a specific system state.     

Meaningful modeling: what's the semantics of "semantics"?

The Unified Modeling Language (UML) is a complex collection of mostly diagrammatic notations for software modeling, and its standardization has prompted an animated discussion about UML's semantics and how to represent it. We have thus set out to clarify some of the notions involved in defining modeling languages, with an eye toward the particular difficulties arising in defining UML. We are primarily interested in distinguishing a language's notation, or syntax, from its meaning, or semantics, as well as recognizing the differences between variants of syntax and semantics in their nature, purpose, style, and use.     

基于UML协作图和DFA的测试用例生成方法研究

UML协作图能够描述对象之间动态的交互关系及对象之间消息传递的过程,根据协作图中的消息流和控制流可以获取有用的场景模型并生成测试用例。本文在研究UML协作图和确定有穷自动机（DFA）之间对应关系的基础上,提出一种将UML协作图转换为DFA,再从DFA中提取测试场景生成测试用例的方法,并将该方法应用于实际项目的测试用例生成。最后,通过对结果进行数据对比和分析,说明该测试用例生成方法的有效性。     

构件行为模型的构造研究

提出了基于 UML构件规格说明自动构造构件行为模型的方法 ,并用一个实例对该方法进行了说明。该方法构造的构件行为模型包含状态与状态之间的转换 ,接口操作作为状态转换弧上的输入 ,能够很好地体现接口的操作调用序列 ,因而可以作为构件测试的测试模型 ,对于构件的开发者和使用者进行构件的黑盒测试以及第三方构件的评估很有价值。     

一种面向列车控制系统中安全攸关场景的测试用例自动生成方法

列车控制系统是一种安全攸关系统,为保证其安全性,要求测试过程对安全攸关场景中所有可能的运行进行完全的覆盖.现有的场景建模与测试用例自动生成方法不能完全满足这一技术需求.围绕列车控制系统的安全攸关场景建模以及测试用例自动生成方法展开研究,对UML活动图扩充了事件驱动机制和时间特性描述机制,以满足对安全攸关场景建模的需要,提出了简单路径覆盖准则以定义对场景中所有运行的完全覆盖,并针对这一覆盖准则给出了自动生成测试用例的方法.以地铁列车控制系统为研究对象展开实验,表明了该方法的有效性和局限性.     

基于场景分析的系统形式化模型生成方法

采用形式化方法对系统的安全性进行分析与验证,是构造可靠安全软件系统的一个重要途径。当前的形式化安全分析方法,面临着系统的形式化建模难的问题。以铁路车站联锁系统中基本进路建立为例,提出基于场景分析的系统形式化模型生成方法。该方法首先采用OCL前/后置条件分析法对UML时序场景作一致性分析,然后将UML时序图中对象交互的行为序列转换成FSP进程代数模型,进而得到系统的形式化模型。该方法为系统的形式化建模提供了新思路,从安全质量方面改善了安全苛求软件的设计与开发,丰厚了基于模型的软件形式化开发方法。     

基于UML活动图生成系统测试场景的方法

旨在研究运用统一建模语言（UML）活动图生成测试场景的方法。首先对UML活动图进行了形式化定义,确定了一系列覆盖准则。然后,根据覆盖准则制定活动图的一般处理思路,针对活动图中并发结构提出采用信号量和嵌套分割的方法进行处理。该方法有效控制了测试场景集的数量,为UML活动图的自动化测试提供了系统的、有效的、可行的方法。     

A metamodeling approach for pattern specification and management

The formal specification of design patterns is central to pattern research and is the foundation of solving various pattern-related problems.In this paper,we propose a metamodeling approach for pattern specification,in which a pattern is modeled as a meta-level class and its participants are meta-level references.Instead of defining a new metamodel,we reuse the Unified Modeling Language(UML)metamodel and incorporate the concepts of Variable and Set into our approach,which are unavailable in the UML but essential for pattern specification.Our approach provides straightforward solutions for pattern-related problems,such as pattern instantiation,evolution,and implementation.By integrating the solutions into a single framework,we can construct a pattern management system,in which patterns can be instantiated,evolved,and implemented in a correct and manageable way.     

Adaptively entropy-based weighting classifiers in combination using Dempster–Shafer theory for word sense disambiguation

In this paper we introduce an evidential reasoning based framework for weighted combination of classifiers for word sense disambiguation (WSD). Within this framework, we propose a new way of defining adaptively weights of individual classifiers based on ambiguity measures associated with their decisions with respect to each particular pattern under classification, where the ambiguity measure is defined by Shannon’s entropy. We then apply the discounting-and-combination scheme in Dempster–Shafer theory of evidence to derive a consensus decision for the classification task at hand. Experimentally, we conduct two scenarios of combining classifiers with the discussed method of weighting. In the first scenario, each individual classifier corresponds to a well-known learning algorithm and all of them use the same representation of context regarding the target word to be disambiguated, while in the second scenario the same learning algorithm applied to individual classifiers but each of them uses a distinct representation of the target word. These experimental scenarios are tested on English lexical samples of Senseval-2 and Senseval-3 resulting in an improvement in overall accuracy.     

Explicit modeling of semantics associated with composite states in UML statecharts

UML statecharts are used for describing dynamic aspects of system behavior. The work presented here extends a general Petri net-based methodology to support formal modeling of UML statecharts. The approach focuses on the specific task of generating explicit transition models associated with the hierarchical structure of statechart. We introduce a state-transition notation to serve as an intermediate model for conversion of UML statecharts, and in particular, the complexity of composite states, to other target specifications. By defining a process for deriving, from UML statecharts, a state-transition notation that can serve as an intermediate state machine model, we seek to deepen understanding of modeling practices and help bridge the gap between model development and model analysis. This work covers all of the primary issues associated with the hierarchical structure of composite states, including entry and exit transitions, transition priorities, history states, and event dispatching. Thus, the results provide an important step forward toward the goal of modeling increasingly complex semantics of UML statecharts. This material is based upon work supported by the U.S. Army Research Office under grant number DAAD19-01-1-1-0672, and the U.S. National Science Foundation under grant number CCR-9988168.     

UML活动图的操作语义

越来越多的系统采用UML（unified model language,统一建模语言）作为建模语言来进行系统分析和设计.UML活动图是UML语言中描述系统动态行为的一种方法,它广泛地运用于业务建模.由于UML活动图缺乏精确的动态语义,所以不利于对其所描述的系统进行形式化的分析、验证和确认.为解决这一问题,根据UML1.5语义文档,给出UML活动图的形式化操作语义.首先给出UML活动图的形式化的语法,然后详细地定义了活动图的格局和变迁,最后基于LTS给出了活动图的演绎规则.主要工作是：引入状态包的概念,使得描述更加清楚、完善;通过LTS定义活动图的操作语义,并详细阐述演绎规则,从而获得活动图的全局状态转移图,使定义的操作语义很容易地应用到形式化验证中.该语义覆盖了UML活动图的绝大部分特征,为对UML活动图进行模型检验奠定了基础.     

Domain mapping using extended UML object diagrams

Many modeling domains can be meta modeled using the core UML structural concepts. When the user needs other specific forms generated from models in such domains, such as source code, model transformations should be defined. The author advocates a specification method for defining model translation that is visual, making specifications easier to create and modify     

基于UML和组件技术的软件开发环境IUMLSE的研究与实现

统一建模语言UML（Unified Modeling Language）正逐步成为面向对象技术领域内占主导地位的建模语言。而组件（Component）技术的蓬勃发展使基于组件组装的软件开发成为可能。两者正无可争议地成为当今和未来软件开发的主流技术。文章对UML和组件技术进行了描述,探讨了两者在软件开发中的作用和相互之间的联系,以及新一代的软件开发环境应该如何对两者提供支持,然后详细介绍了基于UML和组件技术的软件开发环境IUMLSE的设计和实现。     

On the automated translational execution of the action language for foundational UML

To manage the rapidly growing complexity of software development, abstraction and automation have been recognised as powerful means. Among the techniques pushing for them, model-driven engineering has gained increasing attention from industry for, among others, the possibility to automatically generate code from models. To generate fully executable code, models should describe complex behaviours. While pragmatically this is achieved by employing programming languages for defining actions within models, the abstraction gap between modelling and programming languages can undermine consistency between models and code as well as analysability and reusability of models. In light of this, model-aware action languages should be preferred. This is the case of the Action Language for Foundational UML (ALF). In this paper, we provide a solution for the fully automated translational execution of ALF towards C++. Additionally, we give an insight on how to simplify the transition from the use of programming languages for modelling fine-grained behaviours to model-aware action languages in industrial MDE. The solution presented in this paper has been assessed on industrial applications to verify its applicability to complex systems as well as its scalability.     

A Contract-based Approach to Specifying and Verifying Safety Critical Systems

Light-weight formal method has been regarded as an important approach to development of component-based safety critical systems. The paper proposes an approach which can formally specify and verify the contract of static structure, dynamic behavior and refinement of component systems based on UML 2.0 superstructure. As results, the correctness of static contract can be obtained via type checking of interfaces and connectors. Dynamic contract can be verified through determining the cooperativeness of integrated components, whose contracts are depicted with interface protocol state machines and their semantics models, namely contract automata. The refinement relation between high level component and its implementation will be guaranteed through defining the alternating simulation between contract automata of components at different levels.     

模态顺序图uMSD 的形式语义

UML 2.0顺序图已广泛应用于业界,但其语义模糊,以至于不能有效地加以使用.模态顺序图(modal sequence diagram,简称MSD)是对UML 2.0顺序图的模态扩展,区分了强制场景(用universal MSD表示,简称uMSD)和可能场景(用existential MSD表示,简称eMSD).其中,uMSD具有较强的表达能力,能够用于表示并发系统的时态性质,故主要工作围绕uMSD展开.为了使uMSD用于形式化分析、验证和监控,给出基于自动机的uMSD语义解释,并给出各种操作符的算法,用性质规约模式度量uMSD的表达能力.最后进行了实例研究,并讨论了其应用前景.     

一种基于UML动态视图的测试场景生成方法

本文提出一种基于UML动态视图的测试场景生成方法。通过将状态图中对象的状态信息加入顺序图,构建一个基于UML动态视图的测试模型,将其转化为扩展的十字链表结构的有向图;针对测试模型中存在的普通、条件、循环消息类型提出相应的处理方法,采用深度优先算法遍历生成测试场景。在将复杂的UML图转化为测试模型的过程中,应用该方法可以提高所生成场景路径的完整性,同时降低生成场景的冗余度。