A Representational Framework for Scenarios of System Use

Scenarios are becoming widely used in three areas of system development: software engineering, human–computer interaction (HCI), and organisational process design. There are many reasons to use scenarios during system design. The one usually advanced in support of the practice is to aid the processes of validating the developers’ understanding of the customers’ or users’ work practices, organisational goals and structures, and system requirements. All three areas identified above deal with these processes, and not surprisingly this has given rise to a profusion of scenario-based practices and representations. Yet there has been little analysis of why scenarios should be useful, let alone whether they are. Only by having such a framework for understanding what scenarios are, and what they are for, can we begin to evaluate different scenario approaches in specific development contexts. This paper is a contribution toward such a framework. We lay out a space of representational possibilities for scenarios and enumerate a set of values or criteria that are important for different uses of scenarios. We then summarise several salient representations drawn from the software engineering, HCI, and organisational process design communities to clarify how these representational choices contribute to or detract from the goals of the respective practices. Finally, we discuss how scenario representations from one area of design may be useful in others, and we discuss the relationship between these representations and other significant early-design and requirements engineering practices.     

Designing with scenarios: A critical review of current research and practice

There is a great deal of requirements engineering specifically, and information systems development research in general, in the area of scenarios as the ‘vocabulary’ for discussing and characterising designs for new artefacts. This is partly due to opening up the design process to a variety of participants in a project, and making explicit their ways of working, thinking and interactions with the design products. Scenarios, being concrete, and easy to understand and use, provide the means to describe the design vocabulary. They are used to focus on episodic cases, exchange ideas and thoughts about them effectively, and generally describe requirements and designs for a new artefact from the user’s perspective. In this paper, we review the effectiveness of the current state-of-practice in scenario-based approaches. The objective of this evaluation exercise is to define the requirements for improved ‘by scenario’ approaches to cope with requirements and designs for developing new artefacts.     

Scenarios and task analysis

A Critical Review of Carroll's book on scenario-based design is offered [Making Use: Scenario-Based Design of Human–Computer Interactions (2000)]. Carroll characterises scenarios as ‘stories about use’. The paper demonstrates that Carroll's proposals about scenarios and their use in software engineering can be fitted into the broader framework of task analysis in Human–Computer Interaction.     

Exploring how to use scenarios to discover requirements

This paper investigates the effectiveness of different uses of scenarios on requirements discovery using results from requirements processes in two projects. The first specified requirements on a new aircraft management system at a regional UK airport to reduce its environmental impact. The second specified new work-based learning tools to be adopted by a consortium of organizations. In both projects scenarios were walked through both in facilitated workshops and in the stakeholders’ workplaces using different forms of a scenario tool. In the second project, scenarios were also walked through with a software prototype and creativity prompts. Results revealed both qualitative and quantitative differences in discovered requirements that have potential implications for models of scenario-based requirements discovery and the design of scenario tools.     

Converting scenarios to CSP traces with Mise en Scene for requirements-based programming

The Requirements-to-Design-to-Code (R2D2C) project of NASA’s Software Engineering Laboratory is based on inferring a formal specification expressed in Communicating Sequential Processes (CSP) from system requirements supplied in the form of CSP traces. The traces, in turn, are to be derived from scenarios, a user-friendly medium used to describe the required behavior of computer systems under development. An extensive survey of the “scenario” concept and an overview of scenario-based approaches to system engineering are presented. This work, called Mise en Scene, defines a new scenario medium (scenario notation language, SNL) suitable for control-dominated systems, coupled with a two-stage process for automatic translation of scenarios to a new trace medium (trace notation language, TNL), which encompasses CSP traces. Notes on progress toward a “smart” scenario authoring tool are provided, as well as a detailed case study. This work was originally presented at the Software Engineering Workshop (SEW-31) in March 2007. It was supported by research grants from Canada’s Natural Sciences and Engineering Research Council (NSERC).     

Scenario-Based Methods for Evaluating Collaborative Systems

Evaluating collaborative systems remains a significant challenge. Most evaluation methods approach the problem from one of two extremes: focused evaluation of specific system features, or broad ethnographic investigations of system use in context. In this paper, we develop and demonstrate a middle ground for evaluation: explicit reflections on scenarios of system use coupled with analysis of the consequences of these use scenarios, represented as claims. Extending prior work in scenario-based design and claims analysis, we develop a framework for a multi-perspective, multi-level evaluation of collaborative systems called SWIMs: scenario walkthrough and inspection methods. This approach is centered on the capture, aggregation, and analysis of users’ reflections on system support for specific scenarios. We argue that this approach not only provides the contextual sensitivity and use centricity of ethnographic techniques, but also sufficient structure for method replication, which is common to more feature-based evaluation techniques. We demonstrate with an extensive field study how SWIMs can be used for summative assessment of system performance and organizational contributions, and formative assessment to guide system and feature re-design. Results from the field study provide preliminary indications of the method’s effectiveness and suggest directions for future research.     

CREWS-SAVRE: Scenarios for Acquiring and Validating Requirements

This paper reports research into semi-automatic generation of scenarios for validating software-intensive system requirements. The research was undertaken as part of the ESPRIT IV 21903 CREWS long-term research project. The paper presents the underlying theoretical models of domain knowledge, computational mechanisms and user-driven dialogues needed for scenario generation. It describes how CREWS draws on theoretical results from the ESPRIT III 6353 NATURE basic research action, that is object system models which are abstractions of the fundamental features of different categories of problem domain. CREWS uses these models to generate normal course scenarios, then draws on theoretical and empirical research from cognitive science, human-computer interaction, collaborative systems and software engineering to generate alternative courses for these scenarios. The paper describes a computational mechanism for deriving use cases from object system models, simple rules to link actions in a use case, taxonomies of classes of exceptions which give rise to alternative courses in scenarios, and a computational mechanism for generation of multiple scenarios from a use case specification.     

Requirements Management: A Cinderella Story

Why do the business requirements and the final software product often have little in common? Why are stakeholders, developers and managers reluctant to embrace a full requirements process? Why does everybody say, ‘We don’t have time for requirements’? Why is the potentially most beneficial part of the development process ignored or short-changed?  Following are some observations about why the real requirements for the product often go undiscovered. We will address this by focusing on the different concerns of the people involved in requirements.     

基于UCM的Web应用集成测试方法

UCM（Use Case Map）是一种基于场景的软件工程技术,能够以场景的形式模拟系统的功能。用于以可视化的方式描述一个或多个用例中行为之间的因果关系。文章提出一种基于UCM的web应用集成测试方法。该方法首先利用UCM描述Web系统的行为,得到测试场景,然后对测试场景参数化,最后通过对参数进行实例化生成具体的测试例。     

The design and effect of automated directions during scenario-based training

During scenario-based training, the scenario is dynamically adapted in real time to control the storyline and increase its effectiveness. A team of experienced staff members is required to manage and perform the adaptations. They manipulate the storyline and the level of support during their role-play of important characters in the scenario. The costs of training could be reduced if the adaptation is automated by using intelligent agent technology to control the characters within a virtual training environment (a serious game). However, such a system also needs a didactical component to monitor the trainee and determine necessary adaptations to the scenario. This paper investigates the automation of didactical knowledge and the corresponding dynamic adaptation of the scenario. A so-called director decides upon and distributes the necessary changes in real-time to the characters. First, the nature and goals of the adaptations are analyzed. Subsequently, the paper introduces a conducted study into the applicability of directable scenarios. Thereafter, an experiment is introduced that investigates the effects of directorial interventions upon the instructive quality of the scenario. Qualitative results indicated that trainees experienced scenario-based training to be instructive and motivating. Moreover, quantitative results showed that instructors rated directed scenarios as significantly better attuned to the trainee's needs compared to non-directed scenarios. Our future research will focus at the design of an architecture for automatically directed scenario-based training.     

A Framework for Improving the Requirements Engineering Process Management

This paper presents a system dynamics model for improving the requirements engineering process management. The paper argues that improving RE process management improves the quality of the specification produced. It uses a simulation modelling approach to capture the complex and dynamic nature of quality and also the cost of resources and time needed to complete the process. Current claims by various researchers and empirical evidence has led to our proposition that “the earlier in the requirements engineering phase that system dynamics simulation modelling is used, the more effective the RE process management is and the better its product quality will be.” In developing such a model, the paper fills an important gap in the RE process management literature and has potential to provide requirement engineers, managers and software development organisations with a model-based process framework to aid quality assessment and improvement. The paper concludes by suggesting that the framework makes a useful contribution both in providing the foundations for theory building in RE process management and quality improvement by aiding shared understanding through learning and training situations. This revised version was published online in August 2006 with corrections to the Cover Date.     

User and design requirements and production of evidence: using incident analysis data to (1) inform user scenarios and bow ties,and (2) generate user and design requirements

This paper reports on an innovative human–machine interaction methodology adopted to assess the case, role and requirements for a new ground collision awareness technology. Specifically, this paper reports on the analysis of ground collision incident data and the subsequent advancement of user scenarios and bow-ties based on this data analysis, for the purpose of generating preliminary user and design requirements for this technology. In so doing, the requirements elicitation and validation methods used in this research are framed from an epistemological perspective. Accordingly, the particular methods adopted are presented and discussed in terms of concepts of evidence, bearing witness and the distinction between facts and values. As such, this paper promotes thinking about evidence-based design practices. Overall, this evidence-based approach aims to improve the development of scenarios and associated problem solving around technology cases, user requirements and user interface design features. The proposed method is useful in terms of bridging the gap from data analysis to design, and validating design decisions. In this regard, it is argued that the generation of user scenarios based on the analysis of incident data (i.e. data coding and statistical analysis), and the reframing of such scenarios in terms of bow-ties for the purpose of requirements/design envisionment, extends existing scenario-based design approaches. Although the use of bow-ties is not new, the advancement of bow-ties from data-driven scenarios is. Specifically, the bow-tie method was applied in a design context, to support problem solving around design decisions, as opposed to formal risk analysis.     

Studying Software Engineers: Data Collection Techniques for Software Field Studies

Software engineering is an intensively people-oriented activity, yet too little is known about how designers, maintainers, requirements analysts and all other types of software engineers perform their work. In order to improve software engineering tools and practice, it is therefore essential to conduct field studies, i.e. to study real practitioners as they solve real problems. To do so effectively, however, requires an understanding of the techniques most suited to each type of field study task. In this paper, we provide a taxonomy of techniques, focusing on those for data collection. The taxonomy is organized according to the degree of human intervention each requires. For each technique, we provide examples from the literature, an analysis of some of its advantages and disadvantages, and a discussion of how to use it effectively. We also briefly talk about field study design in general, and data analysis.The authors appear in alphabetical order and contributed equally.     

Industry needs and research directions in requirements engineering for embedded systems

The industry has a strong demand for sophisticated requirements engineering (RE) methods in order to manage the high complexity of requirements specifications for software-intensive embedded systems and ensure a high requirements quality. RE methods and techniques proposed by research are only slowly adopted by the industry. An important step to improve the adoption of novel RE approaches is to gain a detailed understanding of the needs, expectations, and constraints that RE approaches must satisfy. We have conducted an industrial study to gain an in-depth understanding of practitioners’ needs concerning RE research and method development. The study involved qualitative interviews as well as quantitative data collection by means of questionnaires. We report on the main results of our study related to five aspects of RE approaches: the use of requirements models, the support for high system complexity, quality assurance for requirements, the transition between RE and architecture design, and the interrelation of RE and safety engineering. Based on the results of the study, we draw conclusions for future RE research.