Deriving objects from use cases in real-time embedded systems

In recent years, a number of use case-driven processes have emerged for the development of real-time embedded systems. In these processes, once requirements have been defined by use cases, the next step is usually to identify from that use cases, the central objects in the system and describing how they interact with one another. However, identifying objects/classes from the requirements is both a critical and hard task. This is mainly due to the lack of pragmatic technique that steers such a task. In this article, we present a systematic approach to identify objects from the use case model for the real-time embedded systems. After hierarchically decomposing the system into its parts, we first transform the use case structured-text style into an activity diagram, which may be reused in the next development activities. Second, we use the derived activity diagram for identifying objects. With the behavioural model, an object model can be viewed as a first cut at a design model, and is thus an essential input when the system is shaped in design and design implementation.     

基于UML的系统测试用例自动生成

提出了一种新颖的基于UML图自动生成系统测试用例的方法.此方法适用于所有UML建模的系统.用创新性地结合图论知识,对用例图和序列图进行抽象,定义了相应的测试覆盖准则以生成测试用例.通过两级遍历,自动生成系统测试向最,并且达到所提的系统测试覆盖率的要求.能够覆盖所有用例、用例依赖性、以及交互中所有的消息序列.实现最大化的...     

Investigating the Role of Use Cases in the Construction of Class Diagrams

Several approaches have been proposed for the transition from functional requirements to object-oriented design. In a use case-driven development process, the use cases are important input for the identification of classes and their methods. There is, however, no established, empirically validated technique for the transition from use cases to class diagrams. One recommended technique is to derive classes by analyzing the use cases. It has, nevertheless, been reported that this technique leads to problems, such as the developers missing requirements and mistaking requirements for design. An alternative technique is to identify classes from a textual requirements specification and subsequently apply the use case model to validate the resulting class diagram. This paper describes two controlled experiments conducted to investigate these two approaches to applying use case models in an object-oriented design process. The first experiment was conducted with 53 students as subjects. Half of the subjects used a professional modelling tool; the other half used pen and paper. The second experiment was conducted with 22 professional software developers as subjects, all of whom used one of several modelling tools. The first experiment showed that applying use cases to validate class diagrams constructed from textual requirements led to more complete class diagrams than did the derivation of classes from a use case model. In the second experiment, however, we found no such difference between the two techniques. In both experiments, deriving class diagrams from the use cases led to a better structure of the class diagrams. The results of the experiments therefore show that the technique chosen for the transition from use cases to class diagrams affects the quality of the class diagrams, but also that the effects of the techniques depend on the categories of developer applying it and on the tool with which the technique is applied.     

基于UML活动图的用例识别

在面向对象的软件开发过程中,统一建模语言(unified modeling language, UML)的用例图用于捕获用户的需求.传统描述用例的方法一般是开发者根据自己的经验,从需求中人工获取用例.然而,如何自动生成准确的用例仍然是一个待解决的问题.本文提出了一种通过用UML活动图半自动生成用例的方法.首先通过引入形式化模型——统一结构来描述用例图与活动图,其次给出分解活动图的算法,然后根据分解活动图得到的依赖链生成对应的用例的事件流,从而得到用例模型,最后通过所开发的原型CASE工具进行案例的演示,验证了本文所提出的方法的可行性。     

逆向工程中动静态结合辅助用例模型的恢复

由于根据目前方法调用之间的“线索”或方法调用的相互关系恢复出的用例模型存在一定的局限性,该文提出了一种基于动态信息并结合静态信息的用例模型恢复方法。该方法以动态运行时的方法调用序列提取基本用例,依据静态的类间关系和静态的程序依赖图对基本用例进行调整、找出用例与角色的交互点及各用例所属的功能模块,使产生的用例模型带有语义信息,更好地辅助用户理解。     

Synthesis of test scenarios using UML activity diagrams

Often system developers follow Unified Modeling Language (UML) activity diagrams to depict all possible flows of controls commonly known as scenarios of use cases. Hence, an activity diagram is treated as a useful design artifact to identify all possible scenarios and then check faults in scenarios of a use case. However, identification of all possible scenarios and then testing with activity diagrams is a challenging task because several control flow constructs and their nested combinations make path identification difficult. In this paper, we address this problem and propose an approach to identify all scenarios from activity diagrams and use them to test use cases. The proposed approach is based on the classification of control constructs followed by a transformation approach which takes into account any combination of nested structures and transforms an activity diagram into a model called Intermediate Testable Model (ITM). We use ITM to generate test scenarios. With our approach it is possible to generate more scenarios than the existing work. Further, the proposed approach can be directly carried out using design models without any addition of testability information unlike the existing approaches.     

一个可视化的用例描述层次模型

用例可采用可视化建模语言UML的用例图、活动图和顺序图来描述,规范且直观,但难于保证图形间的一致性,且在活动图和顺序图中难以体现用例的包含、扩展和泛化关系。文章在深入研究已有的用例描述方法的基础上,提出了一种可视化的用例描述层次模型。该模型将用例分为服务层、结构层和事件层三个抽象层次来描述,容易保证图形间的一致性,且在结构层可以灵活地描述用例间的三个关系。     

一个可视化的用例描述层次模型

用例可采用可视化建模语言UML的用例图、活动图和顺序图来描述，规范且直观，但难于保证图形间的一致性，且在活动图和顺序图中难以体现用例的包含、扩展和泛化关系。文章在深入研究已有的用例描述方法的基础上，提出了一种可视化的用例描述层次模型。该模型将用例分为服务层、结构层和事件层三个抽象层次采描述，容易保证图形间稍一致性，且在结构层可以灵活地描述用例间的三个关系。     

基于设计演算的形式化用例分析建模框架

提出一种形式化用例分析建模框架,引入类图、用例顺序图、用例状态图、功能规约函数和系统不变式从多个角度为需求建模.通过定义这些视图的形式化语义,为需求的各个方面定义了准确的形式化描述.利用该框架,可以从方法的交互行为规约和功能规约合成描述方法全部行为的全规约;也可以定义用例模型的性质,并通过设计演算中的证明来分析验证这些性质.作为应用,研究了检查用例模型一致性的规则.给出一个实例说明建模框架的可行性.     

基于事件序列的用例描述形式化及分析

针对用例描述,提出了基于事件序列的轻量形式化定义。对于由包含、扩展或泛化关系构成的复合用例,构造了相应的算法确定其对应的事件序列,并证明了任意一个无关联环的复合用例均可通过这些算法确定对应的事件序列表达式。在形式化定义基础上,可进行用例描述间关联的正确性分析及语义等价分析。     

面向对象的类的状态测试技术研究

从类的状态模式、状态转移图以及UML状态图等三方面讨论了类的状态测试问题,提出了基于UML类图的类的状态模式测试用例生成方法,介绍了基于状态转移图的类测试方法及其对象状态测试模式在类的状态测试中的运用,讨论了基于UML状态图的测试模型——EFSM 模型的类测试方法。     

基于用况图的程序理解方法研究

用况图从用户的角度描述了系统需求,是表达系统功能的有效方式。如果能从系统源代码中直接抽象程序的用况图,对于程序理解工作将具有很大的帮助。基于此理念,提出了基于用况图的辅助用户程序理解方法。该方法通过静态分析把源代码抽象为树型图表达结构,通过度量计算树型图中各类结点值并生成带权的树型图,根据设定的阈值对该图进行剪裁来控制程序复杂度,通过对剪裁后的树型图进行遍历形成系统的执行路径集合,抽象为最终的候选用况。在图形化工具的辅助支持下从候选用况中抽象出系统的用况图,实验分析取得良好效果。     

一种利用动态信息叠加生成用例模型的方法

提出一种利用动态信息叠加生成用例模型的方法。该方法可以利用多次收集到的动态信息,叠加生成目标系统的用例模型并以UML用例图的形式呈现。通过实验测试,使用该方法恢复出来的用例模型接近于实际模型,证明了该方法的有效性。     

一种安全需求分析中的用例漏洞检测方法

提出一种基于攻击模式的用例漏洞检测方法,用于对需求分析人员设计的用例图进行漏洞检测。该方法以形式化用例作为基础,把误用例作为安全攸关信息的载体、设置为用例的特殊属性。通过与用户的交互完成误用例相关属性的信息采集,并进一步运用这些信息计算出用例的误用例指数。将此指数与预定义的攻击模式相关指数进行对比,以此来判断该用例是否与某个特定误用例、某些特定攻击模式相关。从而检测到用例图中的用例漏洞,并在此基础上提出可行建议。     

基于领域Use Case需求模型的测试用例生成

传统的Use case模型已经被扩展用于建立领域需求模型,但该模型并不支持领域测试用例的复用和自动生成.给出了领域用例的形式化定义方式,增加了最小数据触发集的描述,提出了用例的动态模型和静态模型概念.扩展活动图用于表示用例之间的动态关系和执行过程,并将值流和对象流融入到活动图的表示中.依据用例的动态模型,可以直接产生测试用例,同时获取测试数据,从而实现领域软件需求与领域测试用例的裁剪过程一致性和同步性.