Contributions published at Requirements Engineering (Martin Glinz)

Software modeling is a complex task divided into multiple stages of reiterating drafts and technical solutions. In early stages of modeling design sketches are often created on a traditional whiteboard or with the help of paper and pen. FlexiSketch Desktop is a prototype created to support software engineers in this phase with an electronic solution. It combines the benefits of formal modeling tools with the freedom of unrestricted sketching applications. However FlexiSketch Desktop was created under the one-user/one-computer paradigm. This leaves several issues if we want to use the software on multi-user and multi-touch friendly systems like e-whiteboards. To make FlexiSketch Desktop benefit from the possibilities of other more natural input methods like gesture control we propose a prototype that integrates the features of FlexiSketch Desktop with the ability for multiple users to collaborate simultaneously through multi-touch devices.

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Nowadays, the amount of mobile devices and different mobile systems is enormous. For every mobile device and for every system there exist many different applications. Having to program an application for every platform separately is very tedious and requires a lot of time and resources. FlexiSketch is a free-hand modelling application, developed at the University of Zurich, which at the time exists only for Android and as a Java desktop version. To overcome this lack of platform-support, we propose a cross-platform solution for FlexiSketch in this thesis. Moreover, we present the results and findings of an evaluation of the cross-platform prototype, which can be taken for further development and work.

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Software systems are embedded into daily life and as such have significant effects on the behavior and decision making of both their users and the people affected by using these systems. Such effects can be positive or negative. Considering them in requirements engineering (RE) is an important step towards sustainable development, as RE strongly influences the development and the evolution of a software system. So far, RE researchers have focused on requirements about minimizing negative environmental effects. However, effects that are enabled by using a software system can also be positive. For example, a software system could motivate its users to take environment-friendly decisions. Corresponding requirements about such positive enabling effects have been far less addressed. In this paper, we present an exploratory case study where we elicited requirements about positive enabling effects with respect to environmental sustainability. The project we studied is about extending an existing decision support system for meal planning in canteens by game-based elements. The extended system shall motivate meal planners who work in canteens to make environment-friendly choices. Our contribution is an exemplar of concrete sustainability requirements as well as insight into the nature of sustainability requirements about positive effects that are enabled by the use of a software system.

Requirements engineers model the system of interest from different points of view by creating numerous artifacts. Although they have to deal with a great amount of information, the display space of the devices is limited. This limitation leads to a time consuming navigation through the artifacts. Requirements engineers have to scroll through numerous pages and switch between multiple windows. However, they have to rely on their memory when there is no space left on the screen to view another piece of relevant information. In this research, we propose to develop a novel visualization technique that flexibly creates editable views of a linked set of elements or artifacts where the pieces show different levels of detail according to the user’s demand for the current task. Thus, important parts are shown in detail, while the space taken for displaying unimportant parts is minimized. Our conceptual solution is a combination of the focus+context concept and a magnet-and-spring system. The focus+context concept is responsible for resizing and relocating objects to make space for more relevant information. The magnet-and-spring system is responsible for distributing the distortion caused by the focus+context concept throughout the workspace, such that the distorted view of the information looks more natural. Considering the artifacts of a software development project as a single hypothetical artifact enables us to manage the artifacts in the same way we deal with the objects inside an artifact. Our envisaged tool support should be embeddable in requirements applications and bring its benefits to the applications manipulating requirements artifacts.

Requirements elicitation is indispensable for delivering successful services. Nevertheless, cloud service providers mostly rely on ad-hoc approaches, as there are no dedicated elicitation methods for cloud services. To address this problem, we developed the StakeCloud approach, which helps cloud providers elicit requirements for future cloud services. StakeCloud builds and analyzes fuzzy Galois lattices based on consumers’ advanced search queries for cloud services. Our StakeCloud Tool automatically builds the lattice from the given search queries. It provides the requirements analyst with extensive clustering and analysis capabilities as well as means for comparing different newly generated classes of services. These allow identifying the threshold for achieving the largest populations of satisfied consumers with a minimum set of features implemented. Further, our tool enables eliciting real requirements from global consumers unobtrusively.

Whiteboards and paper allow for any kind of notations and are easy to use. Requirements engineers love to use them in creative requirements elicitation and design sessions. However, the resulting diagram sketches cannot be interpreted by software modeling tools. We have developed FlexiSketch as an alternative to whiteboards in previous work. It is a mobile tool for model-based sketching of free-form diagrams that allows the definition and re-use of diagramming notations on the fly. The latest version of the tool, called FlexiSketch Team, supports collaboration with multiple tablets and an electronic whiteboard, such that several users can work simultaneously on the same model sketch. In this paper we present an exploratory study about how novice and experienced engineers sketch and define ad-hoc notations collaboratively in early requirements elicitation sessions when supported by our tool. Results show that participants incrementally build notations by defining language constructs the first time they use them. Participants considered the option to re-use defined constructs to be a big motivational factor for providing type definitions. They found our approach useful for longer sketching sessions and situations where sketches are re-used later on.

The cloud paradigm has become increasingly attractive throughout the recent years due to its both technical and economic foreseen impact. Therefore, researchers’ and practitioners’ attention has been drawn to enhancing the technological characteristics of cloud services, such as performance, scalability or security. However, the topic of identifying and understanding cloud consumers’ real needs has largely been ignored. Existing requirements elicitation methods are not appropriate for the cloud computing domain, where consumers are highly heterogeneous and geographically distributed, have frequent change requests and expect services to be delivered at a fast pace. In this paper, we introduce a new approach to requirements elicitation for cloud services, which utilizes consumers’ advanced search queries for services to infer requirements that can lead to new cloud solutions. For this, starting from the queries, we build fuzzy Galois lattices that can be used by public cloud providers to analyze market needs and trends, as well as optimum solutions for satisfying the largest populations possible with a minimum set of features implemented. This new approach complements the existing requirements elicitation techniques in that it is a dedicated cloud method which operates with data that already exists, without entailing the active participation of consumers and requirements specialists.

Requirements elicitation is a vital part of software and requirements engineering and therefore indispensable in the development of successful software systems. Insufficient compatibility of the elicitation technique and the project may lead to a result, which does not fit the stakeholders’ needs. Because of this, numerous elicitation techniques have been developed. However, in the emerging market of cloud systems, where Stakeholders are numerous and not reachable, traditional elicitation techniques do not suffice anymore. The StakeCloud approach fills this gap by analyzing advanced search queries for services for inferring your requirements. In this Bachelor thesis, we improve the performance of the StakeCloud prototype by refactoring and applying parallelization techniques. Additionally, further features enhancing automation of the StakeCloud approach are added.

This thesis about how engineers and persons in the domain of software engineering search for information. It mainly builds upon a qualitative field study conducted with 20 face-to-face interviews. Findings of the study are put into historical context to analyse how search patterns changed due to the high increase in digitised documents available within company archives as well as outside sources. Among others, one outcome of the study is the different search behaviour of younger generations - born in the digital age after 1980 - and older persons. An outlook on how future search functions may help improve information lookup is given in the final section of the thesis.

Sustainability has emerged as a broad concern for society. Many engineering disciplines have been grappling with challenges in how we sustain technical, social and ecological systems. In the software engineering community, for example, maintainability has been a concern for a long time. But too often, these issues are treated in isolation from one another. Misperceptions among practitioners and research communities persist, rooted in a lack of coherent understanding of sustainability, and how it relates to software systems research and practice. This article presents a cross-disciplinary initiative to create a common ground and a point of reference for the global community of research and practice in software and sustainability, to be used for effectively communicating key issues, goals, values and principles of sustainability design for software-intensive systems. The centrepiece of this effort is the Karlskrona Manifesto for Sustainability Design, a vehicle for a much needed conversation about sustainability within and beyond the software community, and an articulation of the fundamental principles underpinning design choices that affect sustainability. We describe the motivation for developing this manifesto, including some considerations of the genre of the manifesto as well as the dynamics of its creation. We illustrate the collaborative reflective writing process and present the current edition of the manifesto itself. We assess immediate implications and applications of the articulated principles, compare these to current practice, and suggest future steps.

When software engineers collaborate, they frequently use whiteboards or paper for sketching diagrams. This is fast and flexible, but the resulting diagrams cannot be interpreted by software modeling tools. We present FLEXISKETCH TEAM, a tool solution consisting of a significantly extended version of our previous, single-user FLEXISKETCH tool for Android devices and a new desktop tool. Our solution for collaborative, model- based sketching of free-form diagrams allows users to define and re-use diagramming notations on the fly. Several users can work simultaneously on the same model sketch with multiple tablets. The desktop tool provides a shared view of the drawing canvas which can be projected onto an electronic whiteboard. Preliminary results from an exploratory study show that our tool motivates meeting participants to actively take part in sketching as well as defining ad-hoc notations. Demo video: http://youtu.be/0kHjNfHLViM

Requirements elicitation is a crucial phase in a software project because it helps discover the intended system goals, its stakeholders and their needs. With the emergence of cloud services which represent an innovative way of creating and offering hardware and software, the requirements elicitation phase is all the more important in order to guarantee the success of these new software systems. Within the framework of the cloud services requirements elicitation process, the StakeCloud approach has been proposed as a novel method to support an automatic and an unobstructive requirements elicitation activity. This novel approach implies scrutinizing advanced search queries for cloud services with fuzzy Galois lattices. However, the use of fuzzy Galois lattices can result in lattices that have a very large size and thus become complex and impossible to visualize. From a requirements elicitation point of view, a solution needs to be found that allows the manageability of the resulting complexity. One possible approach to deal with lattices of very large size is clustering. Moreover it will be highly beneficial to allow consumers who request cloud services to state how important a cloud service is to them through the use of priorities. In its current form the StakeCloud approach lacks both clustering and priority management capabilities. In the present thesis we address these two problems by enhancing the StakeCloud approach with clustering and priority management capabilities. We do that by designing and implementing a similarity classifier and a feature priority manager. We test the enhanced StakeCloud tool on small datasets (250, 500, 1000, 1500 search queries) and on bigger datasets (20 000, 25 000, 30 000 search queries). The results obtained confirm the ability of the enhanced StakeCloud tool to manage very large and complex lattices. This in turn enhances the requirements elicitation process for cloud services. The main contribution of this thesis lies in the ability of the enhanced StakeCloud tool to manage very large datasets of search queries thereby improving the real-world requirements elicitation for a very large number of consumers of cloud services.

Updating the requirements specification when software systems evolve is a manual task that is expensive and time consuming. Therefore, maintainers usually apply the changes to the code directly and leave the requirements unchanged. This results in the requirements rapidly becoming obsolete and useless. In this paper, we propose an approach that supports the maintainer in keeping the requirements specification consistent with the implementation, by identifying the requirements that are impacted whenever the code is changed. Our approach works as follows. First, we analyze the changes that have been applied to the source code and detect if they are likely to impact the requirements or not. Second, we trace the requirements-impacting changes back to the requirements specification to identify the parts that might need to be modified. The output of the tracing is a list of requirements that are sorted according to their likelihood of being impacted. Automatically identifying the parts of the requirements specification that are likely to need maintenance reduces the effort needed for keeping the requirements up-to-date and thus makes the task of the maintainer easier. When applying our approach in three cases studies, 70% to 100% of the impacted requirements were identified within a list that includes less than 20% of the total number of requirements in the specification.

Requirements engineers create large numbers of artifacts when eliciting and documenting requirements. They need to navigate through these artifacts and display information details at points of interest for reviewing or editing information. [Question/problem] Traditional visualization mechanisms such as scrolling and opening multiple windows lose context when navigating and can be cumbersome to use, hence. On the other hand, focus+context approaches can display details in context, but they distort the data shown (e.g., fisheye views) or result in a large display canvas which again requires scrolling (e.g., zooming in ADORA). [Principal ideas/results] We are developing a novel method for displaying just the information needed to perform an intended task. Our method partitions the available screen space into regions. The boundaries of regions are simulated with a model consisting of virtual magnetic balls and springs that behaves like a physical system. This model supports the requirements engineer in selecting how the relevant information should be displayed. [Contribution] In this paper, we present preliminary results on how our conceptual solution works and what benefits are expected.

Applying appropriate requirements elicitation techniques is a vital precondition for delivering successful systems. When eliciting requirements for cloud services, however, existing methods such as workshops are challenged and some are even rendered obsolete. Therefore, we interviewed 19 cloud provider companies to understand the current state of practice regarding the adoption and implementation of existing elicitation methods. Our talk summarizes the results of this recent exploratory study [TSG13], showing that only a few cloud providers try to implement and adapt traditional methods, whereas the large majority uses adhoc approaches for identifying consumer needs. Ad-hoc methods range from guessing and inventing requirements to imitating competitors, and generally lead to dissatisfaction among cloud providers. This situation is mostly caused by the incompatibility of traditional methods with the cloud paradigm, hence motivating the investigation of dedicated elicitation techniques for the cloud. After clarifying the challenges and identifying key features for cloud-specific methods, we introduce a new approach for understanding cloud consumers’ needs. This approach analyzes customers’ advanced search queries for services, and interprets them using fuzzy Galois lattices [TG14]. Further, this new technique allows eliciting real requirements unobtrusively and at a global scale.