05 Fakultät Informatik, Elektrotechnik und Informationstechnik
Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/6
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Item Open Access Empirical research plan: effects of sketching on program comprehension(2016) Baltes, Sebastian; Wagner, StefanSketching is an important means of communication in software engineering practice. Yet, there is little research investigating the use of sketches. We want to contribute a better understanding of sketching, in particular its use during program comprehension. We propose a controlled experiment to investigate the effectiveness and efficiency of program comprehension with the support of sketches as well as what sketches are used in what way.Item Open Access Experiences with applying STPA to software-intensive systems in the automotive domain(2013) Abdulkhaleq, Asim; Wagner, StefanHazard analysis is one of the most important elements in developing safe-critical systems. STPA (Systems-Theoretic Process Analysis) is a modern technique based on the new accident causation model STAMP (System-Theoretic Accident Model and Process) for analyzing hazard and safety issues, which can be applied early in the design process of a system to achieve an acceptable risk level. We have applied STPA to a well-known example of safety-critical systems in the automotive industries: Adaptive Cruise Control (ACC). The results of the application of STPA to our case study and the limitations and difficulties of applying STPA are presented.Item Open Access Field study on requirements engineering: investigation of artefacts, project parameters, and execution strategies(2012) Méndez Fernández, Daniel; Wagner, Stefan; Lochmann, Klaus; Baumann, Andrea; Carne, Holger deContext Requirements Engineering (RE) is a critical discipline mostly driven by uncertainty, since it is influenced by the customer domain or by the development process model used. Volatile project environments restrict the choice of methods and the decision about which artefacts to produce in RE. Objective We aim to investigate RE processes in successful project environments to discover characteristics and strategies that allow us to elaborate RE tailoring approaches in the future. Method We perform a field study on a set of projects at one company. First, we investigate by content analysis which RE artefacts were produced in each project and to what extent they were produced. Second, we perform qualitative analysis of semi-structured interviews to discover project parameters that relate to the produced artefacts. Third, we use cluster analysis to infer artefact patterns and probable RE execution strategies, which are the responses to specific project parameters. Fourth, we investigate by statistical tests the effort spent in each strategy in relation to the effort spent in change requests to evaluate the efficiency of execution strategies. Results We identified three artefact patterns and corresponding execution strategies. Each strategy covers different project parameters that impact the creation of certain artefacts. The effort analysis shows that the strategies have no significant differences in their effort and efficiency. Conclusions In contrast to our initial assumption that an increased effort in requirements engineering lowers the probability of change requests or project failures in general, our results show no statistically significant difference between the efficiency of the strategies. In addition, it turned out that many parameters considered as the main causes for project failures can be successfully handled. Hence, practitioners can apply the artefact patterns and related project parameters to tailor the RE process according to individual project characteristics.Item Open Access Where do we stand in requirements engineering improvement today? : first results from a mapping study(2014) Méndez Fernández, Daniel; Ognawala, Saahil; Wagner, Stefan; Daneva, MayaRequirements engineering process improvement (REPI) approaches have gained much attention in research and practice. So far, however, there is no comprehensive view on the research in REPI in terms of solutions and current state of reported evidence. This paper aims to provide an overview on the existing solutions, their underlying principles and their research type facets, i.e. their state of empirical evidence. To this end, we conducted a systematic mapping study of the REPI publication space. This paper reports on the first findings regarding research type facets of the contributions as well as selected methodological principles. We found a strong focus in the existing research on solution proposals for REPI approaches that concentrate on normative assessments and benchmarks of the RE activities rather than on holistic RE improvements according to individual goals of companies. We conclude, so far, that there is a need to broaden the work and to investigate more problem-driven REPI which also targets the improvement of the quality of the underlying RE artefacts.Item Open Access Are suggestions of coupled file changes interesting?(2016) Ramadani, Jasmin; Wagner, StefanSoftware repositories include information which can be made available for bug fixing or maintenance using repository mining. The identification of coupled changes have been proposed several times. Yet, existing studies focus on the found couplings and ignore feedback from developers. We investigate three development projects and their repositories to find files that frequently change together to support the software developers. We complement the coupled files information with details from the issue tracking system and the project documentation. We contrast our findings with feedback from the developers about how interesting our findings are for them. We found that the small size of the repositories made an insightful analysis difficult. The response to coupled changes both from experienced and inexperienced developers was mostly neutral. They accepted most of the additional attributes we presented. Furthermore, developers also suggested other additional issues to be relevant, e.g. the context of the coupled changes and the way they are presented, which we did not cover in this study. Therefore, coupled change analysis research will need to take the presentation and context information into account.Item Open Access An industrial case study on the evaluation of a safety engineering approach for software-intensive systems in the automotive domain(2016) Abdulkhaleq, Asim; Vöst, Sebastian; Wagner, Stefan; Thomas, JohnSafety remains one of the essential and vital aspects in today's automotive systems. These systems, however, become ever more complex and dependent on software which is responsible for most of their critical functions. Therefore, the software components need to be analysed and verified appropriately in the context of software safety. The complexity of software systems makes defining software safety requirements with traditional safety analysis techniques difficult. A new technique called STPA (Systems-Theoretic Process Analysis) based on system and control theory has been developed by Leveson to cope with complex systems. Based on STPA, we have developed a comprehensive software safety engineering approach in which the software and safety engineers integrate the analysis of software risks with their verification to recognize the software-related hazards and reduce the risks to a low level. In this paper, we explore and evaluate the application of our approach to a real industrial system in the automotive domain. The case study was conducted analysing the software controller of the Active Cruise Control System (ACC) of the BMW Group.Item Open Access Mining Java packages for developer profiles : an exploratory study(2017) Ramadani, Jasmin; Wagner, StefanItem Open Access A comprehensive safety engineering approach for software-intensive systems based on STPA(2015) Abdulkhaleq, Asim; Wagner, Stefan; Leveson, NancyFormal verification and testing are complementary approaches which are used in the development process to verify the functional correctness of software. However, the correctness of software cannot ensure the safe operation of safety-critical software systems. The software must be verified against its safety requirements which are identified by safety analysis, to ensure that potential hazardous causes cannot occur. The complexity of software makes defining appropriate software safety requirements with traditional safety analysis techniques difficult. STPA (Systems-Theoretic Processes Analysis) is a unique safety analysis approach that has been developed to identify system hazards, including the software-related hazards. This paper presents a comprehensive safety engineering approach based on STPA, including software testing and model checking approaches for the purpose of developing safe software. The proposed approach can be embedded within a defined software engineering process or applied to existing software systems, allow software and safety engineers integrate the analysis of software risks with their verification. The application of the proposed approach is illustrated with an automotive software controller.Item Open Access Interdisciplinary system courses - teaching agile systems engineering(2019) Seitz, Andreas; Avezum, Mariana; Bruegge, Bernd; Wagner, StefanWith the advent of technologies like the Internet of Things, Industry 4.0 and Cyber-Physical Systems, many software engineering courses turn into system engineering courses. Recent advances in technologies such as 3D printing and low-cost micro controllers enable to teach agile hard- and software co-design in system engineering courses. In this paper, we describe Interdisciplinary System Courses (ISC) - a teaching approach based on interdisciplinary projects, light-weight agile techniques and solving real problems by integrating industry customers. We describe our experiences from an exploratory case study where we applied ISC in a two-week international summer school with a customer from the aerospace industry. We derive a set of hypotheses on the effects of ISC.Item Open Access Towards applying a safety analysis and verification method based on STPA to agile software development(2016) Wang, Yang; Wagner, StefanThis paper presents a novel agile process model "S-Scrum" based on the existing development process "Safe Scrum" and extended by a safety analysis method and a safety verification approach based on STPA (System-Theoretic Process Analysis).