Contributions published at Requirements Engineering (Martin Glinz)

Integrating novel software systems in our society, economy and environment can have far-reaching effects. As a result, software systems should be designed in such a way as to maintain or improve the sustainability of their intended socio-technical systems. However, a paradigm shift is required to raise awareness of software professionals on the potential sustainability effects of software systems. While Requirements Engineering is considered the key for driving this change, requirements engineers lack the knowledge, experience and methodological support for acting as facilitators for a broader discussion on sustainability effects. This paper presents a question-based framework for raising awareness of the potential effects of software systems on sustainability, as the first step towards enabling the required paradigm shift. An evaluation study of the framework was conducted with four groups of computer science students. The results of the study indicate that the framework is applicable to different types of systems and helps to facilitate discussions about the potential effects that software systems could have on sustainability.

Stakeholder participation is a key success factor of Requirements Engineering (RE). Typically, the techniques used for identifying and involving stakeholders in RE assume that stakeholders can be identified among the members of the organizations involved when a software system is ordered, developed or maintained—and that these stakeholders can be told or even mandated to contribute. However, these assumptions no longer hold for many of today’s software systems where significant stakeholders (in particular, end-users and people affected by a system) are outside organizational reach: They are neither known nor can they easily be identified in the involved organizations nor can they be told to participate in RE activities. We have developed the GARUSO approach to address this problem. It uses a strategy for identifying stakeholders outside organizational reach and a social media platform that applies gamification for motivating these stakeholders to participate in RE activities. In this article, we describe the GARUSO approach and report on its empirical evaluation. We found that the identification strategy attracted a crowd of stakeholders outside organizational reach to the GARUSO platform and motivated them to participate voluntarily in collaborative RE activities. From our findings, we derived a first set of design principles on how to involve stakeholders outside organizational reach in RE. Our work expands the body of knowledge on crowd RE regarding stakeholders outside organizational reach.

Sustainability—the capacity to endure—has emerged as a concern of central relevance for society. However, the nature of sustainability is distinct from other concerns addressed by computing research, such as automation, self-adaptation, or intelligent systems. It demands the consideration of environmental resources, economic prosperity, individual well being, social welfare, and the evolvability of technical systems. Thus, it requires a focus not just on productivity, effectiveness, and efficiency, but also the consideration of longer-term, cumulative, and systemic effects of technology interventions, as well as lateral side effects not foreseen at the time of implementation. Furthermore, sustainability includes normative elements and encompasses multi-disciplinary aspects and potentially diverging views. As a wicked problem (see the sidebar “Wicked Problems”), it challenges business-as-usual in many areas of engineering and computing research.

Nowadays, there exist a plethora of different educational syllabi for Requirements Engineering (RE), all aiming at incorporating practically relevant educational units (EUs). Many of these syllabi are based, in one way or the other, on the syllabi provided by the International Requirements Engineering Board (IREB), a non-profit organisation devoted to standardised certification programs for RE. IREB syllabi are developed by RE experts and are, thus, based on the assumption that they address topics of practical relevance. However, little is known about to what extent practitioners actually perceive those contents as useful. We have started a study to investigate the relevance of the EUs included in the IREB Foundation Level certification programme. In the first phase reported in this paper, we have surveyed practitioners mainly from DACH countries (Germany, Austria and Switzerland) who participated in the IREB certification. Later phases will widen the scope both by including other countries and by not requiring IREB-certified participants. The results shall foster a critical reflection on the practical relevance of EUs built upon the de-facto standard syllabus of IREB.

Engineers commonly use paper and whiteboards to sketch and discuss ideas in early phases of requirements elicitation and software modeling. These physical media foster creativity because they are quick to use and do not restrict in any way the form in which content can be drawn. If the sketched information needs to be reused later on, however, engineers have to spend extra effort for preserving the information in a form that can be processed by a software modeling tool. While saving information in a machine-readable way comes for free with formal software modeling tools, they typically anticipate the use of specific, predefined modeling languages and therefore hamper creativity. To combine the advantages of informal and formal tools, we have developed a flexible tool-supported modeling approach that augments a sketching environment with lightweight metamodeling capabilities. Users can create their own modeling languages by defining sketched constructs on demand and export model sketches as semiformal models. In this article, we first give an overview of FlexiSketch and then focus on an evaluation of our approach with two studies conducted with both novice modelers and experienced practitioners. Our goal was to find out how well modelers manage to use our lightweight metamodeling mechanisms, and how they build notations collaboratively. Results show that experienced modelers adopt our approach quickly, while novices have difficulties to distinguish between the model and metamodel levels and would benefit from additional guidance and user awareness features. The lessons learned from our studies can serve as advice for similar flexible modeling approaches.

[Context and motivation] With the rise of cyber-physical systems (CPS), smart ecosystems, and the Internet of Things (IoT), software-intensive systems have become pervasive in everyone’s daily life. The shift from software systems to ubiquitous adaptive software-intensive systems not only affects the way we use software but further has an impact on the way these systems are designed and developed. Gathering requirements for such systems can benefit from elicitation processes that are conducted in the field with domain experts. [Question/problem] More traditional elicitation approaches such as interviews or workshops exhibit limitations when it comes to gathering requirements for systems of this nature – often lacking an in-depth context analysis and understanding of contextual constraints which are easily missed in a formal elicitation setting. Furthermore, dedicated methods which focus on understanding the system context such as contextual design are not widely adopted by the industry as they are perceived to be time-consuming and cumbersome to apply. [Principal ideas/results]. In this research preview paper we argue that scenario-based RE, scenario walkthrough approaches in particular, have the potential to support requirements elicitation for ubiquitous adaptive software-intensive systems through facilitating broader stakeholder involvement and enabling contextual requirements elicitation within the workplace of future system end-users. The envisioned on-site scenario walkthroughs can either be conducted by an analyst or by future end-users of the system themselves. [Contribution] We describe a research agenda including our ongoing research and our efforts to develop a novel framework and tool support for scenario-based RE.

Context: When software-based systems evolve, their requirements change. The changes in requirements affect the associated acceptance tests, which should be adapted accordingly. In practice, however, requirements and their acceptance tests are not always kept up-to-date nor aligned. Such inconsistencies may introduce software quality problems, unintended costs and project delays. Objective: In order to keep evolving requirements and their acceptance tests aligned, we are developing an approach called GuideGen. GuideGen automatically generates guidance in natural language about how to adapt the impacted acceptance tests when their requirements change. Method: We have implemented GuideGen as a prototype tool and evaluated it in two studies: first, by assessing the correctness, completeness, understandability and relevance of the generated guidance using three data sets from industry and second, by assessing the applicability and usefulness of the approach and the tool with 23 practitioners from ten companies. When a requirement having more than one associated acceptance test is changed, GuideGen currently generates guidance for all of them together. As a first step towards overcoming this limitation, we assessed how well existing methods for change impact analysis can identify the tests actually impacted by the changes in a requirement. Results: In the first study, we found that GuideGen produced correct guidance in about 67 to 89 percent of all changes. Our approach performed better for agile requirements than for traditional ones. The results of the second study show that GuideGen is perceived to be useful, but that the practitioners would prefer a GuideGen plug-in for commercial tools instead of a standalone tool. Further, in our experiment we could correctly identify the affected acceptance tests for 63% to 91% of the changes in the requirements. Conclusion: Our approach facilitates the alignment of acceptance tests with the actual requirements and can improve the communication between requirements engineers and testers.

Stakeholder participation is a cornerstone of effective Requirements Engineering (RE). It supports the development and evolution of software systems so that they fit their intended purpose within their application domain. To enable successful stakeholder participation RE experts have created a broad variety of approaches for different circumstances and project phases. These approaches focus on traditionally dedicated software systems, which have closed and location-bound user groups. The stakeholders of these systems usually are members of the organizations that commission or build the system. Meanwhile, technological development has opened doors for ubiquitously deployed and openly available software systems. Stakeholders of these systems are rarely members of those organizations. Instead, they are so-called outside organizational reach and typically unknown to RE experts. Hence, in contrast to stakeholders of traditionally dedicated software systems, they can neither straightforwardly be identified nor be requested to participate in RE. Moreover, they are likely location-independent, numerous and highly heterogeneous. Current RE approaches do not suffice to address these challenges. Established RE approaches provide limited means to identify stake- holders outside organizational reach, let alone motivate them to voluntarily participate in RE. They also cannot support collaboration in distributed settings or on a large scale, yet, collaboration is known to be essential for the development of novel systems and in unknown domains. Feedback mechanisms and social network sites enable distributed and large-scale collaboration. However, their effectiveness is limited as they originally have no RE purpose and typically are restricted to their members. Latest RE approaches close this gap and also apply motivation strategies, which, however, are simplified, missing the high heterogeneity of stakeholders out- side organizational reach; thus, risking to demotivate them. This thesis presents the GARUSO (Game-based Requirements Elicitation) approach, a novel RE approach specifically designed for stakeholders outside organizational reach. It provides (1) a strategy to identify them and (2) a social media based platform that enables their collaborative participation in RE and applies gamification to motivate them to do so. The GARUSO platform is the core of the thesis. Its conceptual solution is inspired by the structure of user stories, the experiential learning theory, motivational psychology and game design. As a proof of concept, it was implemented to elicit and prioritize requirements and evaluated in a field study with promising results: The identified stakeholders build a highly heterogeneous crowd which participated - over a period of three months - in platform activities. They perceived the platform easy to understand, interesting to use and during their participation increased their knowledge on the application domain of the software system of interest.

Continuous requirements elicitation is an essential aspect of software product evolution to keep systems aligned with changing user needs. However, current requirements engineering approaches do not explicitly address sustainability in the evolution of systems. Reasons include a lack of awareness and a lack of shared understanding of the concept of sustainability in the RE community. Identifying and analysing the effects of requirements regarding sustainability is challenging, as these effects can have an impact on multiple stakeholders and manifest themselves in one or more sustainability dimensions at different points in time. We argue that crowd-focused semi-automated requirements engineering allows the engagement of a large number of stakeholders (including users and domain experts) in a continuous cycle of negotiation regarding the potential effects of requirements on sustainability. Based on a motivating scenario, we introduce the idea of a platform for crowd-focused requirements engineering that supports the evolution towards sustainability. For the three key aspects of this platform, we present our ongoing work and discuss early results. We outline how the platform can be utilised to improve the broader awareness and understanding of sustainability, not only for the involved crowd but also for researchers and society in general.

Requirements Engineering (RE) plays a critical role in software system development and is argued to be the key leverage point for practitioners who want to design sustainable software-intensive systems. However, existing RE methods and tools do not explicitly facilitate the discussion and negotiation of sustainability-related concerns. This leads to insufficient or onedimensional perceptions of sustainability. In this paper, we discuss our understanding of sustainability and its relationship with requirements. Based on the outcomes of this discussion, we have extended the WinWin Negotiation Model by incorporating sustainability concepts so that the negotiation also includes the ability to consider the impact of requirements on sustainability. Applying this negotiation method in an exploratory industrial case study, we have learned that this approach stimulates the discussion on sustainability and its multiple dimensions. It also allows practitioners to reflect on requirements and their effects on sustainability. However, we have also observed that further in-depth requirements analysis is needed to analyse the long-term effects of requirements regarding sustainability.

Context: Software evolution ensures that software systems in use stay up to date and provide value for end-users. However, it is challenging for requirements engineers to continuously elicit needs for systems used by heterogeneous end-users who are out of organisational reach. Objective: We aim at supporting continuous requirements elicitation by combining user feedback and usage monitoring. Online feedback mechanisms enable end-users to remotely communicate problems, experiences, and opinions, while monitoring provides valuable information about runtime events. It is argued that bringing both information sources together can help requirements engineers to understand end-user needs better. Method/Tool: We present FAME, a framework for the combined and simultaneous collection of feedback and monitoring data in web and mobile contexts to support continuous requirements elicitation. In addition to a detailed discussion of our technical solution, we present the first evidence that FAME can be successfully introduced in real-world contexts. Therefore, we deployed FAME in a web application of a German small and medium-sized enterprise (SME) to collect user feedback and usage data. Results/Conclusion: Our results suggest that FAME not only can be successfully used in industrial environments but that bringing feedback and monitoring data together helps the SME to improve their understanding of end-user needs, ultimately supporting continuous requirements elicitation.

Software requirements constantly change, thus impacting all other artifacts of an evolving system. In order to keep the system in a consistent state, changes in requirements should be documented and applied accordingly to all affected artifacts, including acceptance tests. In practice, however, changes in requirements are not always documented nor applied to the affected acceptance tests. This is mostly due to poor communication, lack of time or work overload, and eventually leads to project delays, unintended costs and unsatisfied customers. GuideGen is a tool-supported approach for keeping requirements and acceptance tests aligned. When a requirement is changed, GuideGen automatically generates guidance in natural language on how to modify impacted acceptance tests and communicates this information to the concerned parties. In this paper, we evaluate GuideGen in terms of its perceived usefulness for practitioners and its applicability to real software projects. The evaluation was conducted via interviews with 23 industrial practitioners from ten companies based in Europe. The results indicate that GuideGen is a useful approach that facilitates requirements change management and the communication of changes between requirements and test engineers. The participants also identified potential for improvement, in particular for using GuideGen in large projects.

There is little research on systematically identifying incentive solutions and motives encouraging users to provide non-public feedback to software systems. Goal of this thesis is to identify end-usersí motives, design incentive solutions, and evaluate the motive-incentive-fit this context. A set of 11 motives was created, based on a literature analysis. Existing commercial tools, research tools and the SUPERSEDE feedback tool were analyzed for their incentive solutions and matched to the motives. Based on that, a SWOT analysis was conducted and supported the notion of optimizing the SUPERSEDE feedback. During a workshop and a prioritization, 93 prioritized incentive solutions were created. After a selection process, 50 promising incentive solutions remained, whereof 31 could be conceptualized or implemented into the SUPERSEDE feedback tool. Finally, the features and concepts were evaluated by 10 users and 4 company representatives. For 80% of the users asked, the optimized SUPERSEDE feedback tool raised their willingness to provide feedback compared to the original SUPERSEDE feedback tool.

App stores allow globally distributed users to submit user feedback, in the form of user reviews, about the apps they download. Previous research has found that many of these reviews contain valuable information for software evolution, such as bug reports or feature requests, and has designed approaches for automatically extracting this information. However, the diversity of the feedback submitted by users from diverse cultural backgrounds and the consequences this diversity might imply have not been studied so far. In this paper, we report on a cross-cultural study where we investigated cultural differences in app store reviews and identified correlations to cultural dimensions taken from a well-established cultural model. We analyzed 2,560 app reviews written by users from eight countries with diverse national culture. We contribute evidence about the influence of cultural factors on characteristics of app reviews. Our results also help developers of automated feedback analysis tools to avoid cultural bias when choosing their algorithms and the data for training and validating them.

When changes in requirements occur, their associated tests must be adapted accordingly in order to maintain the quality of the evolving system. In practice, inconsistencies in requirements and acceptance tests – together with poor communication of changes — lead to software quality problems, unintended costs and project delays. We are developing GuideGen, a tool that helps requirements engineers, testers and other involved parties keep requirements and acceptance tests aligned. When requirements change, GuideGen analyzes the changes, automatically generates guidance on how to adapt the affected acceptance tests, and sends this information to subscribed parties. GuideGen also flags all non-aligned acceptance tests, thus keeping stakeholders aware of mismatches between requirements and acceptance tests. We evaluated GuideGen with data from three companies. For 262 non-trivial changes of requirements, the suggestions generated by GuideGen were correct in more than 80 percent of the cases for agile requirements and about 67 percent for traditional ones.

[Context and motivation] When a software-based system evolves, its requirements continuously change. This affects the acceptance tests, which must be adapted accordingly in order to maintain the quality of the evolving system. [Question/problem] In practice, requirements and acceptance test documents are not always aligned with each other, nor with the actual system behavior. Such inconsistencies may introduce software quality problems, unintended costs and project delays. [Principal ideas/results] To keep evolving requirements and their associated acceptance tests aligned, we are developing an approach called GuideGen that automatically generates guidance in natural language on how to modify impacted acceptance tests when a requirement is changed. We evaluated GuideGen using real-world data from three companies. For 262 non-trivial changes of requirements, we generated guidance on how to change the affected acceptance tests and evaluated the quality of this guidance with seven experts. The correctness of the guidance produced by our approach ranged between 67 and 89 percent of all changes for the three evaluated data sets. We further found that our approach performed better for agile requirements than for traditional ones. [Contribution] Our approach facilitates the alignment of acceptance tests with the actual requirements and also improves the communication between requirements engineers and testers.

The complexity and variety of graphical models (e.g. class diagrams or activity diagrams) lead to a wide range of user interfaces to create and manipulate such graphical models. Moreover, the development of working prototypes for software usability tests is costly. To simplify such usability tests ImitGraphs ñ a specialized graphical model to simulate the behavior of its intended graphical model ñ were proposed in earlier works. To evaluate the behavior of ImitGraphs, we designed and conducted two series of experiments that should test whether participants interact with an ImitGraph similar as with its intended graphical model and if such usability tests can be conducted with participants that have no prior knowledge of designing graphical models. Analyzing the obtained data showed, that participants complete given tasks with similar types and number of steps, regardless of the model used or their experience. Based on the observed behavior we conclude that ImitGraphs could indeed replace the intended graphical models in usability tests and thus allows to conduct more frequent tests in earlier phases of the software development cycle. Also, a wider range of participants with no prior knowledge about designing graphical models could attend usability tests that are based on ImitGraphs.

In Requirements Engineering the use of artifacts is almost inevitable as they simply serve as a resource for better understanding. The tools used to create and edit these artifacts are often cumbersome, especially when dealing with complex and large artifacts [GG16]. In order to counteract this inconvenience, FlexiView [GSG15] was introduced with the idea of displaying the desired information without removing the context view. The screen space is divided into regions and based on physical metaphors (springs and magnets), the regions get stimulated and change its size including the detail level of its content. A basic implementation of the FlexiView approach already existed, but the functionalities were revised and enhanced in this thesis. Furthermore, an editor prototype was developed, which supports interactive graph manipulation with the help of FlexiView. The editor itself provides conventional features to create and edit graphical models, but can simply switch over to use the FlexiView method. In this thesis, the existing part of FlexiView is documented and the final prototype is presented with several challenges highlighted, that emerged during development.