A specification pattern for use cases

In this paper, general formats and guidelines are proposed, in an attempt to ameliorate the impact of frequently observed difficulties during the specification of use cases generated using “natural language” for the documentation of system functionality. The various writing styles derived from the multiple grammatical alternatives found in the Spanish language and the terminological diversity that characterises this language tend to reduce the clarity of text in a use-case specification. Thus, the purpose of its use in the different stages of development in a software system or component is seriously affected. However, even if this study has been made specifically for the Spanish language, it could be easily generalised to any language whose sentences are of the form subject/predicate. In order to control these problems, the use of a specification pattern supported by a series of guidelines on style and terminology is proposed for drafting use cases. Additionally, various degrees of refinement are suggested to guide specifiers towards obtaining a use case written according to this pattern.     

An investigation of use case quality in a large safety-critical software development project

Use case modelling is a much-used technique for eliciting and documenting functional requirements. The quality of the use cases may have an important impact on the development project and on the resulting software product. This paper presents an empirical study of the changes that were made to the use case models in a large software project during the analysis phase. The results show (a) which were the most difficult aspects of use case modelling in this project and (b) how the quality of the functional requirements, in particular correctness, completeness, and clarity, was improved through the use case modelling process.     

Testing the predictive ability of a requirements pattern language

This paper looks at a case study in the commercial procurement of an IT system to support learners on short educational courses. It compares the use case model created before the system was built with the use case model after the system was delivered. The original use case model was created through the application of a requirements pattern language designed to be employed during the procurement phase of an IT system. The final use case model was reverse engineered from the working application. The objective was to discover how accurately the original model represented the final application to provide a measure of the potential usefulness of the pattern language during procurement.     

Applications of linguistic techniques for use case analysis

Use cases are effective techniques to express the functional requirements of a system in a very simple and easy-to-learn way. Use cases are mainly composed of natural language (NL) sentences, and the use of NL to describe the behaviour of a system is always a critical point, due to the inherent ambiguities originating from the different possible interpretations of NL sentences. We discuss in this paper the application of analysis techniques based on a linguistic approach to detect, within requirements documents, defects related to such an inherent ambiguity. Starting from the proposed analysis techniques, we will define some metrics that will be used to perform a quality evaluation of requirements documents. Some available automatic tools supporting the linguistic analysis of NL requirements have been used to evaluate an industrial use cases document according to the defined metrics. A discussion on the application of linguistic analysis techniques to support the semantic analysis of use cases is also reported.     

Transforming an enterprise model into a use case model in business process systems

One of the responsibilities of requirements engineering is to transform stakeholder requirements into system and software requirements. For enterprise systems, this transformation must consider the enterprise context where the system will be deployed. Although there are some approaches for detailing stakeholder requirements, some of them even considering the enterprise context, this task is executed manually. Based on model-driven engineering concepts, this study proposes a semi-automatic transformation from an enterprise model to a use case model. The enterprise model is used as a source of information about the stakeholder requirements and domain knowledge, while the use case model is used as software requirements model. This study presents the source and target metamodels, a set of transformation rules, and a tool to support the transformation. An experiment analyzes the use of the proposed transformation to investigate its benefits and if it can be used in practice, from the point of view of students in the context of a requirements refinement. The results indicate that the approach can be used in practice, as it did not influence the quality of the generated use cases. However, the empirical analysis does not indicate benefits of using the transformation, even if the qualitative results were positive.     

Use Case驱动的软件需求获取过程模型

对Use Case建模进行分析后,提出了基于Use Case驱动的软件需求获取过程模型。该模型中通过不断迭代的两个阶段：分析阶段和综合阶段,来正确和完整地获取软件需求。文章对此模型进行了描述,并就一些关键问题展开了讨论,最后介绍了软件需求获取中的一些常用技术。     

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。     

Control case approach to record and model non-functional requirements

While the functional requirements of a system can be effectively modeled through the use case driven approach, there is no standard or de facto method for modeling non-functional requirements (NFR) of the system architecture. Often such requirements are dealt with in a reactive manner, rather than proactively. Yet increasingly a contributing factor in project difficulty and failure are the NFR imposed on the solution architecture. This paper outlines a control case approach to record and model NFR. This technique enables the control case to represent the NFR from different perspectives, most typically the various operating conditions. We also propose an extension to the “4 + 1” view model for depicting software architecture by adding the control case view. In addition, a detailed control case modeling example is illustrated to demonstrate how these techniques may be applied during development. Taken together, we suggest that the combination of both the use case and control case views thus reflects the complete requirements across the collective system life cycle views: design, process, implementation and deployment.     

用UML活动图集成用例的研究

在对UML建模语言进行了简单介绍之后,论述了在用UML用例图进行需求描述的基础上描述用例之间的复杂联系的重要性。随后介绍了一种以活动图集成用例的方式来表达用例之间联系的方法,并进行了实例分析。     

Producing robust use case diagrams via reverse engineering of use case descriptions

In a use case driven development process, a use case model is utilized by a development team to construct an object-oriented software system. The large degree of informality in use case models, coupled with the fact that use case models directly affect the quality of all aspects of the development process, is a very dangerous combination. Naturally, informal use case models are prone to contain problems, which lead to the injection of defects at a very early stage in the development cycle. In this paper, we propose a structure that will aid the detection and elimination of potential defects caused by inconsistencies present in use case models. The structure contains a small set of formal constructs that will allow use case models to be machine readable while retaining their readability by retaining a large degree of unstructured natural language. In this paper we also propose a process which utilizes the structured use cases to systematically generate their corresponding use case diagrams and vice versa. Finally a tool provides support for the new structure and the new process. To demonstrate the feasibility of this approach, a simple study is conducted using a mock online hockey store system.     

Are use case and class diagrams complementary in requirements analysis? An experimental study on use case and class diagrams in UML

Despite the status of united modeling language (UML) as the de facto standard for object oriented modeling, it has received controversial reviews. The most controversial diagram in UML is the use case diagram. Some practitioners claim that use case diagrams are not valuable in requirements analysis and some have even argued that use case diagrams should not be part of UML. This research examined the values of use case diagram in interpreting requirements when use case diagrams are used in conjunction with class diagrams. In other words, the study investigated the possible synergetic values and relationships between the use case and class diagrams in the context of requirements analysis. This study used theories from cognitive psychology as its theoretical and conceptual foundation. The data collection utilized the verbal protocol technique in which subjects were asked to think aloud as they interpreted the use case and class diagrams. The results show that the use case diagrams were more completely interpreted than the class diagrams. The presence or absence of one diagram when interpreting another diagram had no effect on the outcome of the interpretation. From the results, we argue that the use case diagrams and class diagrams depict different aspects of the problem domain, they have very little overlap in the information captured, and both are necessary in requirements analysis.     

一款IP电话机的需求分析设计

需求分析与规格说明是嵌入式产品开发的一个重要环节。本文以一款IP电话机为例,通过"需求分析与概念性规格说明"以及"图形化规格说明"两部分来介绍这阶段工作要点。     

逆向工程中的用例模型恢复技术

用例和用例模型从用户的角度描述了软件系统的行为特点,它们已经成为程序理解中的一个关键所在。随着逆向工程、程序理解、遗产系统等领域的发展,用例模型恢复的技术也受到越来越多的关注。该文介绍了目前的用例模型恢复技术及其各自特点和适用范围,并对其今后的发展提出了一些建议。