# Requirements Engineering

Online ISSN: 1432-010X
Recent publications
Article
Today, when undertaking requirements elicitation, engineers attend to the needs and wants of the user groups considered relevant for the software system. However, answers to some relevant questions (e.g., how to improve adoption of the intended system) cannot always be addressed through direct need and want elicitation. Using an example of energy demand-response systems, this paper demonstrates that use of grounded theory analysis can help address such questions. The theories emerging from such analysis produce a set of additional requirements which cannot be directly elicited from individuals/groups, and would otherwise be missed. Thus, we demonstrate that the theories generated through grounded theory analysis can serve as additional valuable sources of requirements for software and its wider system. This paper extends our previous work by demonstrating how several theories can be constructed and utilised for a single system analysis.

Article
Requirements are usually written in natural language and evolve continuously during the process of software development, which involves a large number of stakeholders. Stakeholders with diverse backgrounds and skills might refer to the same real-world entity with different linguistic expressions in the natural-language requirements, resulting in requirement inconsistency. We define this phenomenon as Entity Coreference (EC) in the Requirement Engineering (RE) area. It can lead to misconception about technical terminologies, and harm the readability and long-term maintainability of the requirements. In this paper, we propose a DEEP context-wise method for entity COREFerence detection, named DeepCoref. First, we truncate corresponding contexts surrounding entities. Then, we construct a deep context-wise neural network for coreference classification. The network consists of one fine-tuning BERT model for context representation, a Word2Vec-based network for entity representation, and a multi-layer perceptron in the end to fuse and make a trade-off between two representations. Finally, we cluster and normalize coreferent entities. We evaluate our method, respectively, on coreference classification and clustering with 1853 industry data on 21 projects. The former evaluation shows that DeepCoref outperforms three baselines with average precision and recall of 96.10% and 96.06%, respectively. The latter evaluation on six metrics shows that DeepCoref can cluster coreferent entities more accurately. We also conduct ablation experiments with three variants to demonstrate the performance enhancement brought by different components of neural network designed for coreference classification.

Article
The advance of Ubiquitous Computing (UbiComp) and Internet of Things (IoT) brought a new set of Non-Functional Requirements (NFRs), especially related to Human-Computer Interaction (HCI). Invisibility is one of these NFRs and refers to either the merging of technology in the user environment or the decrease in the interaction workload. This new NFR may impact traditional ones (e.g., Usability), revealing positive correlations, when one NFR helps another, and negative correlations, when a procedure favors an NFR but creates difficulty for another one. Correlations between NFRs are usually stored in catalogs, which is a well-defined body of knowledge gathered from previous experience. Although Invisibility has been recently cataloged with development strategies, the literature still lacks catalogs with correlations for this NFR. Therefore, this work aims at capturing and cataloging invisibility correlations for UbiComp and IoT systems. To do that, we also propose to systematize the definition of correlations using the following well-defined research methods: Interview, Content Analysis and Questionnaire. As a result, we defined a catalog with 110 positive and negative correlations with 9 NFRs. We evaluated this correlation catalog using a controlled experiment to verify if it helps developers when they are making decisions about NFRs in UbiComp and IoT systems. Results indicated that the catalog improved the decisions made by the participants. Therefore, this well-defined body of knowledge is useful for supporting software engineers to select appropriate strategies that satisfy Invisibility and other NFRs related to user interaction.

Article
Many software users give feedback online about the applications they use. This feedback often contains valuable requirements information that can be used to guide the effective maintenance and evolution of a software product. Yet, not all software users give online feedback. If the demographics of a user-base aren’t fairly represented, there is a danger that the needs of less vocal users won’t be considered in development. This work investigates feedback on three prominent online channels: app stores, product forums, and social media. We directly survey software users about their feedback habits, as well as what motivates and dissuades them from providing feedback online. In an initial survey of 1040 software users, we identify statistically significant differences in the demographics of users who give feedback (gender, age, etc.), and key differences in what motivates them to engage with each of the three studied channels. In a second survey of 936 software users, we identify the top reasons users don’t give feedback, including significant differences between demographic groups. We also present a detailed list of user-rated methods to encourage their feedback. This work provides meaningful context for requirements sourced from online feedback, identifying demographic groups who are underrepresented. Findings on what motivates and discourages user feedback give insight into how feedback channels and developers can increase engagement with their user-base.

Article
During the software development process and throughout the software lifecycle, organizations must guarantee users’ privacy by protecting personal data. There are several studies in the literature proposing methodologies, techniques, and tools for privacy requirements elicitation. These studies report that practitioners must use systematic approaches to specify these requirements during initial software development activities to avoid users’ data privacy breaches. The main goal of this study is to identify which methodologies, techniques, and tools are used in privacy requirements elicitation in the literature. We have also investigated Information Technology (IT) practitioners’ perceptions regarding the methodologies, techniques, and tools identified in the literature. We have carried out a systematic literature review (SLR) to identify the methodologies, techniques, and tools used for privacy requirements elicitation. Besides, we have surveyed IT practitioners to understand their perception of using these techniques and tools in the software development process. We have found several methodologies, techniques, and tools proposed in the literature to carry out privacy requirements elicitation. Out of 78 studies cataloged within the SLR, most of them did not verify their methodologies and techniques in a practical case study or illustrative contexts (38 studies), and less than 35% of them (26 studies) experimented with their propositions within an industry context. The Privacy Safeguard method (PriS) is the best known among the 198 practitioners in the industry who participated in the survey. Moreover, use cases and user story are their most-used techniques. This qualitative and quantitative study shows a perception of IT practitioners different from those presented in other research papers and suggests that methodologies, techniques, and tools play an important role in IT practitioners’ perceptions about privacy requirements elicitation.

Article
Poorly executed requirements engineering activities profoundly affect the deliverables’ quality and project’s budget and schedule. High-quality requirements reuse through requirement patterns has been widely discussed to mitigate these adverse outcomes. Requirement patterns aggregate similar applications’ behaviors and services into well-defined templates that can be reused in later specifications. The abstraction capabilities of metamodeling have shown promising results concerning the improvement of the requirement specifications’ quality and professionals’ productivity. However, there is a lack of research on requirement patterns beyond requirements engineering, even using metamodels as the underlying structure. Besides, most companies often struggle with the cost, rework, and delay effects resulting from a weak alignment between requirements and testing. In this paper, we present a novel metamodeling approach, called Software Pattern MetaModel (SoPaMM), which aligns requirements and testing through requirement patterns and test patterns. Influenced by well-established agile practices, SoPaMM describes functional requirement patterns and acceptance test patterns as user stories integrated with executable behaviors. Another novelty is the evaluation of SoPaMM’s quality properties against a metamodel quality evaluation framework. We detail the evaluation planning, discuss evaluation results, and present our study’s threats to validity. Our experience with the design and evaluation of SoPaMM is summarized as lessons learned.

Article
A common way to describe requirements in Agile software development is through user stories, which are short descriptions of desired functionality. Nevertheless, there are no widely accepted quantitative metrics to evaluate user stories. We propose a novel metric to evaluate user stories called instability, which measures the number of changes made to a user story after it was assigned to a developer to be implemented in the near future. A user story with a high instability score suggests that it was not detailed and coherent enough to be implemented. The instability of a user story can be automatically extracted from industry-standard issue tracking systems such as Jira by performing retrospective analysis over user stories that were fully implemented. We propose a method for creating prediction models that can identify user stories that will have high instability even before they have been assigned to a developer. Our method works by applying a machine learning algorithm on implemented user stories, considering only features that are available before a user story is assigned to a developer. We evaluate our prediction models on several open-source projects and one commercial project and show that they outperform baseline prediction models.

Article
In regulated domains like automotive, release planning is a complex process. This complex process consists of an agreement between product development processes for hardware as well as mechanic systems and approaches for software development. Particularly in automotive, the creation and synchronization of release plans for hardware as well as software is a challenge. Within the whole complex system development, it is challenging to consider the relevant stakeholders in the initial creation of a release plan. Depending on the context that a release plan shall be created for, there are different stakeholders that have to be considered from the beginning. There are numerous publications in the area of release planning, but there is no detailed research that shows which stakeholders have to be addressed in the automotive context. The aim of this work is to identify stakeholders of a release plan as an appropriate approach to create transparency in release planning in the automotive domain. Action research to elaborate relevant stakeholders for release planning was conducted at Dr. Ing. h. c. F. Porsche AG. We present a detailed overview of identified stakeholders as well as their required content and added value regarding two pilot projects. With this contribution, identified stakeholders of release planning from the hardware and software points of view are introduced. We discuss, based on the results, why there are common stakeholders for the two projects and why there are individual stakeholders for each project. With this work, we present a more complete stakeholder identification and a more detailed understanding of their needs.

Article
Research has repeatedly shown that high-quality requirements are essential for the success of development projects. While the term “quality” is pervasive in the field of requirements engineering and while the body of research on requirements quality is large, there is no meta-study of the field that overviews and compares the concrete quality attributes addressed by the community. To fill this knowledge gap, we conducted a systematic mapping study of the scientific literature. We retrieved 6905 articles from six academic databases, which we filtered down to 105 relevant primary studies. The primary studies use empirical research to explicitly define, improve, or evaluate requirements quality. We found that empirical research on requirements quality focuses on improvement techniques, with very few primary studies addressing evidence-based definitions and evaluations of quality attributes. Among the 12 quality attributes identified, the most prominent in the field are ambiguity, completeness, consistency, and correctness. We identified 111 sub-types of quality attributes such as “template conformance” for consistency or “passive voice” for ambiguity. Ambiguity has the largest share of these sub-types. The artefacts being studied are mostly referred to in the broadest sense as “requirements”, while little research targets quality attributes in specific types of requirements such as use cases or user stories. Our findings highlight the need to conduct more empirically grounded research defining requirements quality, using more varied research methods, and addressing a more diverse set of requirements types.

Article
Assurance case development (ACD) is a novel approach for demonstrating that a system is safe for use. Assurance cases comprise various project information, including requirements and their traceability to other artifacts. A practitioners’ survey was performed to understand how requirements engineering and ACD activities currently interplay. This study aimed to identify the state of practice of ACD, the existing integration between requirements engineering and ACD, and the practitioners’ opinion on this integration. The results revealed that the interplay occurs across all requirement engineering activities and that practitioners perceive benefits such as raising safety assurance awareness, early traceability development, and early identification of assurance evidence needs. Practitioners see requirements specification and change request analysis as the most suitable activities for integrating ACD and requirements engineering.

Article
Quality requirements deal with how well a product should perform the intended functionality, such as start-up time and learnability. Researchers argue they are important and at the same time studies indicate there are deficiencies in practice. Our goal is to review the state of evidence for quality requirements. We want to understand the empirical research on quality requirements topics as well as evaluations of quality requirements solutions. We used a hybrid method for our systematic literature review. We defined a start set based on two literature reviews combined with a keyword-based search from selected publication venues. We snowballed based on the start set. We screened 530 papers and included 84 papers in our review. Case study method is the most common (43), followed by surveys (15) and tests (13). We found no replication studies. The two most commonly studied themes are (1) differentiating characteristics of quality requirements compared to other types of requirements, (2) the importance and prevalence of quality requirements. Quality models, QUPER, and the NFR method are evaluated in several studies, with positive indications. Goal modeling is the only modeling approach evaluated. However, all studies are small scale and long-term costs and impact are not studied. We conclude that more research is needed as empirical research on quality requirements is not increasing at the same rate as software engineering research in general. We see a gap between research and practice. The solutions proposed are usually evaluated in an academic context and surveys on quality requirements in industry indicate unsystematic handling of quality requirements.

Article
Machine Learning (ML) algorithms are widely used in building software-intensive systems, including safety-critical ones. Unlike traditional software components, Machine-Learned Components (MLC)s, software components built using ML algorithms, learn their specifications through generalizing the common features that they find in a limited set of collected examples. While this inductive nature overcomes the limitations of programming hard-to-specify concepts, the same feature becomes problematic for verifying safety in ML-based software systems. One reason is that, due to MLCs data-driven nature, there is often no set of explicitly written and pre-defined specifications, against which the MLC can be verified. In this regard, we propose to partially specify hard-to-specify domain concepts, which MLCs tend to classify, instead of fully relying on their inductive learning ability from arbitrarily-collected datasets. In this paper, we propose a semi-automated approach to construct a multi-level semantic web to partially outline the hard-to-specify, yet crucial, domain concept “pedestrian” in automotive domain. We evaluate the applicability of the generated semantic web in two ways: first, with a reference to the web, we augment a pedestrian dataset for a missing feature, wheelchair, to show training a state-of-the-art ML-based object detector on the augmented dataset improves its accuracy in detecting pedestrians; second, we evaluate the coverage of the generated semantic web based on multiple state-of-the-art pedestrian and human datasets.

Article
Requirements engineering (RE) has established itself as a core software engineering discipline. It is well acknowledged that good RE leads to higher quality software and considerably reduces the risk of failure or budget-overspending of software development projects. It is of vital importance to train future software engineers in RE and educate future requirements engineers to adequately manage requirements in various projects. To this date, there exists no central concept of what RE education shall comprise. To lay a foundation, we report on a systematic literature review of the field and provide a systematic map describing the current state of RE education. Doing so allows us to describe how the educational landscape has changed over the last decade. Results show that only a few established author collaborations exist and that RE education research is predominantly published in venues other than the top RE research venues (i.e., in venues other than the RE conference and journal). Key trends in RE instruction of the past decade include involvement of real or realistic stakeholders, teaching predominantly elicitation as an RE activity, and increasing student factors such as motivation or communication skills. Finally, we discuss open opportunities in RE education, such as training for security requirements and supply chain risk management, as well as developing a pedagogical foundation grounded in evidence of effective instructional approaches.

Article
Model-based testing (MBT) is a method that supports the design and execution of test cases by models that specify the intended behaviors of a system under test. While systematic literature reviews on MBT in general exist, the state of the art on modeling and testing performance requirements has seen much less attention. Therefore, we conducted a systematic mapping study on model-based performance testing. Then, we studied natural language software requirements specifications in order to understand which and how performance requirements are typically specified. Since none of the identified MBT techniques supported a major benefit of modeling, namely identifying faults in requirements specifications, we developed the Performance Requirements verificatiOn and Test EnvironmentS generaTion approach (PRO-TEST). Finally, we evaluated PRO-TEST on 149 requirements specifications. We found and analyzed 57 primary studies from the systematic mapping study and extracted 50 performance requirements models. However, those models don’t achieve the goals of MBT, which are validating requirements, ensuring their testability, and generating the minimum required test cases. We analyzed 77 Software Requirements Specification (SRS) documents, extracted 149 performance requirements from those SRS, and illustrate that with PRO-TEST we can model performance requirements, find issues in those requirements and detect missing ones. We detected three not-quantifiable requirements, 43 not-quantified requirements, and 180 underspecified parameters in the 149 modeled performance requirements. Furthermore, we generated 96 test environments from those models. By modeling performance requirements with PRO-TEST, we can identify issues in the requirements related to their ambiguity, measurability, and completeness. Additionally, it allows to generate parameters for test environments.

Article
Traceability links recovery (TLR) has been a topic of interest for many years. However, TLR approaches are based on the latent semantics of the software artifacts, and are not equipped to deal with software artifacts that lack those inherent semantics, such as BPMN models. The aim of this work is to enhance TLR approaches in BPMN models by incorporating the linguistic particularities of BPMN models into the TLR process. Our approach runs through a threefold contribution: (1) we identify the particularities of BPMN models; (2) we describe how to leverage the particularities; and (3) we build three variants of the best exploratory TLR approach which specifically cater to BPMN models. The approach is evaluated through both an academic case study and a real-world industrial case study. The results show that incorporating the particularities of BPMN into the TLR process leads the specific approach to improve the traceability results obtained by generalist approaches, maintaining precision levels and improving recall. The novel findings of this paper suggest that there is a benefit in researching and taking in account the particularities of the different kinds of models in order to optimize the results of TLR between requirements and models, instead of relying on generalist approaches.

Article
Organizations have increasingly applied agile project management; however, they face challenges in scaling up this approach to large projects. Thus, this study investigates the key barriers and benefits of scaling agile methods to large projects. The research approach is a literature review, applying bibliometrics and content analysis with Bibliometrix and UCINET software. We conducted a sampling process in the Web of Science and Scopus databases and surveyed 76 articles in depth. The results identified 53 barriers clustered into six main categories: organizational issues, managerial issues, agile method-specific barriers, product/process issues, customer issues, and team issues. Thirty-two benefits were coded and clustered into three categories: business, project, and team. Requirement management appears as a core topic, impacting both barriers and benefits for scaling agile project management. We identified a strong relationship between the barriers and benefits. These results can be used to create questionnaires to explore these barriers and benefits in practice.

Article
With the increase in market needs, game development teams are facing a high demand of creating new games every year. Although several methodologies and tools were introduced to support the game development life cycle, there is still a lack of evidence that these techniques improve game requirements understandability among development teams. The use of models in requirements engineering is considered a promising approach to support requirements elicitation, negotiation, validation, and management. In the context of game development, game designers argue that models are hard to learn and would restrict their creativity. In this paper, we introduce a novel use case-based game modeling approach that extends the standard UML use case diagram. The proposed technique allows for better representation of game-related requirements and promotes a common understanding of game requirements among game development teams. Our approach is implemented in a tool, called game use case modeling, and its applicability is demonstrated using four well-known games, Super Mario Bros, Tetris, Just Dance, and The Walking Dead. Moreover, in order to assess the perceived understandability, learnability, and usefulness of the proposed approach, we have conducted a survey involving 29 participants from the game development community. Results indicate a very satisfactory agreement regarding the added value of the proposed approach and a willingness of adoption by the game development community.

Article
Software traceability, the ability to relate software development artifacts such as requirements, design models and code to each other, is an important aspect in software development. It yields a number of benefits such as facilitating impact analysis and tracking software changes. However, for companies to reap these benefits, a proper traceability strategy—a plan for how traceability should be managed—needs to be defined and implemented. Existing literature lacks concrete guidelines for practitioners to systematically define such a strategy. In this study, we address this gap by defining a Traceability Introduction Methodology (TracIMo), which is a methodology for systematically designing, implementing and evaluating software traceability in practice. We used design science research to design TracIMo and evaluated it in a case study with an agile development team of a company in the finance domain. Our results show that TracIMo is feasible as it allows incremental definition and evaluation of a traceability strategy that is aligned with the company’s traceability goals and the existing development process. We also report practical challenges encountered when designing a traceability strategy such as defining the right level of granularity and the need for defining intermediate development artifacts.

Article
Using qualitative data analysis (QDA) to perform domain analysis and modeling has shown great promise. Yet, the evaluation of such approaches has been limited to single-case case studies. While these exploratory cases are valuable for an initial assessment, the evaluation of the efficacy of QDA to solve the suggested problems is restricted by the common single-case case study research design. Using our own method, called QDAcity-RE, as the example, we present an in-depth empirical evaluation of employing qualitative data analysis for domain modeling using a controlled experiment design. Our controlled experiment shows that the QDA-based method leads to a deeper and richer set of domain concepts discovered from the data, while also being more time efficient than the control group using a comparable non-QDA-based method with the same level of traceability.

Article
The increasing complexity of cyber-physical systems (CPSs) makes their design, development and operation extremely challenging. Due to the nature of CPS that involves many heterogeneous components, which are often designed and developed by organizations belonging to different engineering domains, it is difficult to manage, trace and verify their properties, requirements and constraints throughout their lifecycle by using classical techniques. In this context, the paper presents an integrated solution to formally define system requirements and automate their verification through simulation. The solution is based on the FOrmal Requirements Modeling Language and the Modelica language. The solution is exemplified through two case studies concerning a Trailing-Edge High-Lift system and a Heating, Ventilation and Air Conditioning system.

Article
Causal relations in natural language (NL) requirements convey strong, semantic information. Automatically extracting such causal information enables multiple use cases, such as test case generation, but it also requires to reliably detect causal relations in the first place. Currently, this is still a cumbersome task as causality in NL requirements is still barely understood and, thus, barely detectable. In our empirically informed research, we aim at better understanding the notion of causality and supporting the automatic extraction of causal relations in NL requirements. In a first case study, we investigate 14.983 sentences from 53 requirements documents to understand the extent and form in which causality occurs. Second, we present and evaluate a tool-supported approach, called CiRA, for causality detection. We conclude with a second case study where we demonstrate the applicability of our tool and investigate the impact of causality on NL requirements. The first case study shows that causality constitutes around 28 % of all NL requirements sentences. We then demonstrate that our detection tool achieves a macro-F1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\hbox {F}_{1}$$\end{document} score of 82 % on real-world data and that it outperforms related approaches with an average gain of 11.06 % in macro-Recall and 11.43 % in macro-Precision. Finally, our second case study corroborates the positive correlations of causality with features of NL requirements. The results strengthen our confidence in the eligibility of causal relations for downstream reuse, while our tool and publicly available data constitute a first step in the ongoing endeavors of utilizing causality in RE and beyond.

Article
Recommender systems for requirements are typically built on the assumption that similar requirements can be used as proxies to retrieve similar software. When a stakeholder proposes a new requirement, natural language processing (NLP)-based similarity metrics can be exploited to retrieve existing requirements, and in turn, identify previously developed code. Several NLP approaches for similarity computation between requirements are available. However, there is little empirical evidence on their effectiveness for code retrieval. This study compares different NLP approaches, from lexical ones to semantic, deep-learning techniques, and correlates the similarity among requirements with the similarity of their associated software. The evaluation is conducted on real-world requirements from two industrial projects from a railway company. Specifically, the most similar pairs of requirements across two industrial projects are automatically identified using six language models. Then, the trace links between requirements and software are used to identify the software pairs associated with each requirements pair. The software similarity between pairs is then automatically computed with JPLag. Finally, the correlation between requirements similarity and software similarity is evaluated to see which language model shows the highest correlation and is thus more appropriate for code retrieval. In addition, we perform a focus group with members of the company to collect qualitative data. Results show a moderately positive correlation between requirements similarity and software similarity, with the pre-trained deep learning-based BERT language model with preprocessing outperforming the other models. Practitioners confirm that requirements similarity is generally regarded as a proxy for software similarity. However, they also highlight that additional aspect comes into play when deciding software reuse, e.g., domain/project knowledge, information coming from test cases, and trace links. Our work is among the first ones to explore the relationship between requirements and software similarity from a quantitative and qualitative standpoint. This can be useful not only in recommender systems but also in other requirements engineering tasks in which similarity computation is relevant, such as tracing and change impact analysis.

Article
For realistic self-adaptive systems, multiple quality attributes need to be considered and traded off against each other. These quality attributes are commonly encoded in a utility function, for instance, a weighted sum of relevant objectives. Utility functions are typically subject to a set of constraints, i.e., hard requirements that should not be violated by the system. The research agenda for requirements engineering for self-adaptive systems has raised the need for decision-making techniques that consider the trade-offs and priorities of multiple objectives. Human stakeholders need to be engaged in the decision-making process so that constraints and the relative importance of each objective can be correctly elicited. This paper presents a method that supports multiple stakeholders in eliciting constraints, prioritizing relevant quality attributes, negotiating priorities, and giving input to define utility functions for self-adaptive systems. We developed tool support in the form of a blackboard system that aggregates information by different stakeholders, detects conflicts, proposes mechanisms to reach an agreement, and generates a utility function. We performed a think-aloud study with 14 participants to investigate negotiation processes and assess the approach's understandability and user satisfaction. Our study sheds light on how humans reason about and how they negotiate around quality attributes. The mechanisms for conflict detection and resolution were perceived as very useful. Overall, our approach was found to make the process of utility function definition more understandable and transparent.

Article
Requirements specifications are essential to properly communicate requirements among the software development team members. However, each role in the team has different informational needs in order to perform their activities. Thus, the requirements engineer should provide the necessary information to meet each team member's necessities to reduce errors in software development due to inadequate or insufficient communication. Although some research is concerned with communicating requirements among clients and analysts, no related research has been found to evaluate and improve requirements communication within the software development team. With this in mind, we present the ReComP framework, which assists in the identification of problems in the artifacts used to communicate requirements, identification of informational requirements for each role of the development team, and provide improvement suggestions to address requirements communication problems. ReComP was developed using the Design Science Research (DSR) method and this paper presents the results of two DSR cycles considering the use of ReComP for the developer and tester roles by using, respectively, user stories and use cases as requirements specifications. The results provide evidence that ReComP helps software development teams to identify and improve issues in the requirements specifications used for project communication. In two independent studies, ReComP was able to decrease the frequency of problems by 77% in user stories identified by developers and the frequency of all (100%) problems in use cases identified by testers.

Article
To reduce program risks, engineering methods capitalizing on modeling and machine assistance have been extensively investigated within systems engineering (and more specifically requirements engineering) literature over the past 20 years. However, there are few quantitative comparisons between model-based approaches and legacy document-centric approaches. Studies have shown that the lack of data regarding improvements of modeling has decelerated the adoption of model-based practices. To help address this gap, the authors conducted a screening experiment to compare the effects of modeling on an engineer’s ability to determine if a system has met its originating requirements. First, a notional acquisition program was created based on an unmanned aerial system, including originating requirements as well as both document and model-based design artifacts. Requirements were captured in both a traditional requirements document and a goal oriented requirements engineering model. System implementation data were capturing in both traditional document artifacts and a SysML model. Participants of varying experience levels used randomized combinations of document and model-based approaches to determine whether the notional system met its requirements. The experiment measured the review duration and accuracy, permitting analysis of the effects of model-based approaches for both requirements and system implementation data. The results of the experiment showed that use of a requirements model did not statistically effect the review. A system implementation model was shown to improve novice participants’ reviews, but did not statistically effect experienced participants. The results of this study should inform future research on the use of models, particularly the return on the modeling investment.

Article
A correction to this paper has been published: https://doi.org/10.1007/s00766-021-00356-2

Article
Crowdsourcing system requirements enables project managers to elicit feedback from a broader range of stakeholders. The advantages of crowdsourcing include a higher volume of requirements reflecting a more comprehensive array of use cases and a more engaged and committed user base. Researchers cite the inability of project teams to effectively manage an increasing volume of system requirements as a possible drawback. This paper analyzes a data set consisting of project management artifacts from 562 open-source software (OSS) projects to determine how OSS project performance varies as the share of crowdsourced requirements increases using six measures of effectiveness: requirement close-out time, requirement response time, average comment activity, the average number of requirements per crowd member, the average retention time for crowd members, and the total volume of requirements. Additionally, the models measure how the impact of increasing the share of crowdsourced requirements changes with stakeholder network structure. The analysis shows that stakeholder network structure impacts OSS performance outcomes and that the effect changes with the share of crowdsourced requirements. OSS projects with more concentrated stakeholder networks perform the best. The results indicate that requirements crowdsourcing faces diminishing marginal returns. OSS projects that crowdsource more than 70% of their requirements benefit more from implementing processes to organize and prioritize existing requirements than from incentivizing the crowd to generate additional requirements. Analysis in the paper also suggests that OSS projects could benefit from employing CrowdRE techniques and assigning dedicated community managers to more effectively channel input from the crowd.

Article
This article introduces a new class of socio-technical systems, interspecies information systems (IIS) by describing several examples of these systems emerging through the use of commercially available data-driven animal-centered technology. When animal-centered technology, such as pet wearables, cow health monitoring, or even wildlife drones captures animal data and inform humans of actions to take towards animals, interspecies information systems emerge. I discuss the importance of understanding them as information systems rather than isolated technology or technology-mediated interactions, and propose a conceptual model capturing the key components and information flow of a general interspecies information system. I conclude by proposing multiple practical challenges that are faced in the successful design, engineering and use of any IIS where animal data informs human actions.

Article
A correction to this paper has been published: https://doi.org/10.1007/s00766-021-00354-4

Article
In early-phase requirements engineering, modeling stakeholder goals and intentions helps stakeholders understand the problem context and evaluate tradeoffs, by exploring possible “what if” questions. Prior research allows modelers to make evaluation assignments to desired goals and generate possible selections for task and dependency alternatives, but this treats models as static snapshots, where the evaluation of the fulfillment of an intention remains constant once it has been determined. Using these techniques, stakeholders are unable to reason about possible evolutions, leaving questions about project viability unanswered when the fulfillment of goals or availability of components is not guaranteed in the future. In this article, we formalize the Evolving Intentions framework for specifying, modeling, and reasoning about goals that change over time. Using the Tropos language, we specify a set of functions that define how intentions and relationships evolve, and use path-based analysis for asking a variety of “what if” questions about such changes. We illustrate the framework using the Bike Lanes example and prove correctness of the analysis. Finally, we demonstrate scalability and effectiveness, enabling stakeholders to explore model evolution.

Article
Expert judgement is a common method for software effort estimations in practice today. Estimators are often shown extra obsolete requirements together with the real ones to be implemented. Only one previous study has been conducted on if such practices bias the estimations. We conducted six experiments with both students and practitioners to study, and quantify, the effects of obsolete requirements on software estimation. By conducting a family of six experiments using both students and practitioners as research subjects ( $$N=461$$ N = 461 ), and by using a Bayesian Data Analysis approach, we investigated different aspects of this effect. We also argue for, and show an example of, how we by using a Bayesian approach can be more confident in our results and enable further studies with small sample sizes. We found that the presence of obsolete requirements triggered an overestimation in effort across all experiments. The effect, however, was smaller in a field setting compared to using students as subjects. Still, the over-estimations triggered by the obsolete requirements were systematically around twice the percentage of the included obsolete ones, but with a large 95% credible interval. The results have implications for both research and practice in that the found systematic error should be accounted for in both studies on software estimation and, maybe more importantly, in estimation practices to avoid over-estimations due to this systematic error. We partly explain this error to be stemming from the cognitive bias of anchoring-and-adjustment, i.e. the obsolete requirements anchored a much larger software. However, further studies are needed in order to accurately predict this effect.

Article
Goal-oriented requirements engineering aims to capture desired goals and strategies of relevant stakeholders during early requirements engineering stages, using goal models. Goal-oriented modeling techniques support the analysis of system requirements (especially non-functional ones) from an operationalization perspective, through the evaluation of alternative design options. However, conflicts and undesirable interactions between requirements produced from goals are inevitable, especially as stakeholders often aim for different objectives. In this paper, we propose an approach based on game theory and the Goal-oriented Requirement Language (GRL) to reconcile interacting stakeholders (captured as GRL actors), leading to reasonable trade-offs. This approach consists in building a payoff bimatrix that considers all actor’s valid GRL strategies, and computing its Nash equilibrium. Furthermore, we use two optimization techniques to reduce the size of the payoff bimatrix, hence reducing the computational cost of the Nash equilibrium. The approach goes beyond existing work by supporting nonzero-sum games, multiple alternatives, and inter-actor dependencies. We demonstrate the applicability of our game-theoretic modeling and analysis approach using a running example and two GRL models from the literature, with positive results on feasibility and applicability, including performance results.

Article
Risk-aware Business Process Management (R-BPM) has been addressed in research since more than a decade. However, the integration of the two independent research streams is still ongoing with a lack of research focusing on the conceptual modeling perspective. Such an integration results in an increased meta-model complexity and a higher entry barrier for modelers in creating conceptual models and for addressees of the models in comprehending them. Multi-view modeling can reduce this complexity by providing multiple interdependent viewpoints that, all together, represent a complex system. Each viewpoint only covers those concepts that are necessary to separate the different concerns of stakeholders. However, adopting multi-view modeling discloses a number of challenges particularly related to managing consistency which is threatened by semantic and syntactic overlaps between the viewpoints. Moreover, usability and efficiency of multi-view modeling have never been systematically evaluated. This paper reports on the conceptualization, implementation, and empirical evaluation of e-BPRIM, a multi-view modeling extension of the Business Process-Risk Management-Integrated Method (BPRIM). The findings of our research contribute to theory by showing, that multi-view modeling outperforms diagram-oriented modeling by means of usability and efficiency of modeling, and quality of models. Moreover, the developed modeling tool is openly available, allowing its adoption and use in R-BPM practice. Eventually, the detailed presentation of the conceptualization serves as a blueprint for other researchers aiming to harness multi-view modeling.

Article
Collaborative cyber-physical systems are capable of forming networks at runtime to achieve goals that are unachievable for individual systems. They do so by connecting to each other and exchanging information that helps them coordinate their behaviors to achieve shared goals. Their highly complex dependencies, however, are difficult to document using traditional goal modeling approaches. To help developers of collaborative cyber-physical systems leverage the advantages of goal modeling approaches, we developed a GRL-compliant extension to the popular iStar goal modeling language that takes the particularities of collaborative cyber-physical systems and their developers’ needs into account. In particular, our extension provides support for explicitly distinguishing between the goals of the individual collaborative cyber-physical systems and the network and for documenting various dependencies not only among the individual collaborative cyber-physical systems but also between the individual systems and the network. We provide abstract syntax, concrete syntax, and well-formedness rules for the extension. To illustrate the benefits of our extension for goal modeling of collaborative cyber-physical systems, we report on two case studies conducted in different industry domains.

Article
Bridging the gap between academia and industry is an important issue to promote the practicality of i* framework. Researchers have been dealing with this issue from various perspectives, such as simplifying the meta-models or modeling processes of i* framework. In this paper, we exclusively focus on the scalability issue in laying out large-scale i* models and propose a two-level layout approach to automatically lay out i* models in an efficient and comprehensible manner, contributing to the adoption of i* framework in the industry. The proposed approach is designed by considering the semantics of i* constructs and layout conventions of i* models in order to produce meaningful layouts and can appropriately handle both the SD (Strategic Dependency) view and the SR (Strategic Rationale) view of i* models. We have implemented our approach in an open-access prototype tool, which is able to be integrated with existing iStarML-compatible modeling tools. We have conducted a controlled experiment, a case study, and performance testing to empirically and comprehensively evaluate the utility of our approach, the results of which show that our proposal can efficiently produce meaningful layouts that are as comprehensible as manually laid out models in most cases.

Article
Mailing list is widely used as an important channel for communications between developers and stakeholders. It consists of emails that are posted for various purposes, such as reporting problems, seeking help in usage, managing projects, and discussing new features. Due to the intensive amount of new incoming emails every day, some valuable emails that intend to describe new features may get overlooked by developers. However, identifying these feature requests from development emails is a labor-intensive and challenging task. In this paper, we propose an automated solution to discover feature requests from development emails by leveraging semantic sequence patterns. First, we tag sentences in emails by using 81 fuzzy rules proposed in our previous study. Then we represent the semantic sequence with the contextual information of an email in a 2-g model. After applying sequence pattern mining techniques, we generate 10 semantic sequence patterns from 317 tagged emails that are randomly sampled from the Ubuntu community. We also conduct an empirical evaluation of their capability to discover feature requests from massive emails in Ubuntu and other four open source communities. The results show that our approach can effectively identify feature requests from these emails. Compared to existing baselines, our approach can achieve a better performance in terms of precision, recall, F1-score, AUC, and positive, with the average precision and recall for discovering feature requests from emails being 76% and 86%, respectively.

Article
With the rise in initiatives such as software ecosystems and Internet of Things (IoT), developing web Application Programming Interfaces (web APIs) has become an increasingly common practice. One main concern in developing web APIs is that they expose back-end systems and data toward clients. This exposure threatens critical non-functional requirements, such as the security of back-end systems, the performance of provided services, and the privacy of communications with clients. Although dealing with non-functional requirements during software design has been long studied, there is still no framework to specifically assist software developers in addressing these requirements in web APIs. In this paper, we introduce Rational API Designer (RAPID), an open-source assistant that advises on designing non-functional requirements in the architecture of web APIs. We have equipped RAPID with a broad range of expert knowledge about API design, systematically collected and extracted from the literature. The API design knowledge has been encoded as a set of 156 rules using the Non-Functional Requirements (NFR) multi-valued logic, a formal framework commonly used to describe non-functional and functional requirements of software systems. RAPID uses the encoded knowledge in a stepwise inference procedure to arrive from a given requirement, to a set of design alternatives to a final recommendation for a given API design specification. Seven well-experienced software engineers have blindly evaluated the accuracy of RAPID’s consultations over seven different cases of web API design and on providing design guidelines for thirty design questions. The results of the evaluation show that RAPID’s recommendations meet acceptable standards of the majority of the evaluators 73.3% of the time. Moreover, analysis of the evaluators’ comments suggests that more than one-third of the unacceptable ratings (33.8%) given to RAPID’s answers are due to valid but incomplete design guidelines. We thus expect that the accuracy of the consultations will increase as RAPID’s knowledge of API design is extended and refined.

Article
Requirements engineering remains a discipline that is faced with a large number of challenges, including the implementation of a requirements elicitation process in industry. Although several proposals have been suggested by researchers and academics, little is known of the practices that are actually followed in industry. Our objective is to investigate the state-of-practice with respect to requirements elicitation, by closely examining practitioners’ current practices. To this aim, we focus on the techniques that are used in industry, the roles that requirements elicitation involves, and the challenges that the requirements elicitation process is faced with. As method, we conducted an interview-based survey study involving 24 practitioners from 12 different Swedish IT companies, and we recorded the interviews and analyzed these recordings by using quantitative and qualitative methods. Several results emerged from the studies. Group interaction techniques, including meetings and workshops, are the most popular type of elicitation techniques that are employed by the practitioners, except in the case of small projects. Additionally, practitioners tend to use a variety of elicitation techniques in each project. We noted that customers are frequently involved in the elicitation process, except in the case of market-driven organizations. Technical staff (for example, developers and architects) are more frequently involved in the elicitation process compared to the involvement of business or strategic staff. Finally, we identified a number of challenges with respect to stakeholders. These challenges include difficulties in understanding and prioritizing their needs. Further, it was noted that requirements instability (i.e., caused by changing needs or priorities) was a predominant challenge. These observations need to be interpreted in the context of the study. We conclude that the relevant observations regarding the survey participants’ experiences should be of interest to the industry; experiences that should be analyzed in the practitioners’ context. Researchers may find evidence for the use of academic results in practice, thereby inspiring future theoretical work, as well as further empirical studies in the same area.

Article
Implementing machine learning in an enterprise involves tackling a wide range of complexities with respect to requirements elicitation, design, development, and deployment of such solutions. Despite the necessity and relevance of requirements engineering approaches to the process, not much research has been done in this area. This paper employs a case study method to evaluate the expressiveness and usefulness of GR4ML, a conceptual modeling framework for requirements elicitation, design, and development of machine learning solutions. Our results confirm that the framework includes an adequate set of concepts for expressing machine learning requirements and solution design. The case study also demonstrates that the framework can be useful in machine learning projects by revealing new requirements that would have been missed without using the framework, as well as, by facilitating communication among project team members of different roles and backgrounds. Feedback from study participants and areas of improvement to the framework are also discussed.

Article
Requirements selection is a decision-making process that enables project managers to focus on the deliverables that add most value to the project outcome. This task is performed to define which features or requirements will be developed in the next release. It is a complex multi-criteria decision process that has been focused by many research works, because a balance between business profits and investment is needed. The spectrum of prioritization techniques spans from simple and qualitative to elaborated analytic prioritization approaches that fall into the category of optimization algorithms. This work studies the combination of the qualitative MoSCoW method and cluster analysis for requirements selection. The feasibility of our methodology has been tested on three case studies (with 20, 50 and 100 requirements). In each of them, the requirements have been clustered, and then the clustering configurations found have been evaluated using internal validation measures for the compactness, connectivity and separability of the clusters. The experimental results show the validity of clustering strategies for the identification of the core set of requirements for the software product, being the number of categories proposed by MoSCoW a good starting point in requirements prioritization and negotiation.

Article
Nowadays, the growing importance of modelling in software engineering is without a doubt reinforced by the blossoming of model-driven architecture (MDA). In this trend, MDA could be considered the most convenient approach to integrate the modelling process in data warehousing projects. On the other hand, decision-makers are usually unable to express their business needs in a concise way that allows getting a valid data warehouse (DW), mainly due to the lack of standard meth-odologies and tools devoted to supporting this situation. This fact might expand the gap between the business world and the IT world and causes troublesome difficulties to interpret and model DW requirements. Moreover, applying MDA for this kind of project requires using new tools to avoid this drawback. In this paper, we provide an MDA framework to design DW requirements and generate afterwards the multidimensional schema. The framework is based on UML profiles and presents to decision-makers a graphical tool for modelling their strategic visions in order to build the system-to-be. Besides, the proposal allows for dealing with data historization and metadata in the generated multidimensional model to perform properly the extract transform load process.

Article
Industry 4.0 is expected to deliver significant productivity gain taking advantage of Internet of things (IoT). Smart solutions, enhanced by IoT, are constantly driving revolutionary approaches in multiple domains. Smart factories are one domain where intelligent integrated robotic systems will revolutionize manufacturing, resulting in a complex ecosystem, where humans, robots and machinery are combined. In this setting, human safety requirements are of paramount importance. This paper focuses on symbiotic human–robot collaboration systems (HRC), where human safety requirements are essential. Hence, it aims to explore and prioritize human safety requirement dependencies, as well as their dependencies with other critical requirements of smart factory operation, as effectiveness and performance. Toward this end, the proposed approach is based on SysML to represent the requirements dependencies and pairwise comparisons, a fundamental decision-making method, to quantify the importance of these dependencies. This model-driven approach is used as the primary medium for conveying traceability among human safety requirements as well as traceability from safety requirements to effectiveness and performance requirements in the system model. The analysis is based on the operational requirements identified in the European project HORSE, which aims to develop a methodological/technical framework for easy adaptation of robotic solutions from small-/medium-sized enterprises. Validation of the results is also performed to further elaborate on human safety requirement dependency exploration. The outcomes of this paper may be beneficial for symbiotic HRC systems in the early design stage. As the system is being developed with an emphasis on human safety, all these requirements that have been assessed with highly prioritized dependencies should be taken into account, whereas those with negligible ones have to be ignored since they do not significantly affect the rest of the process. Since operational requirements may be conflicted and incompatible, this approach may be very useful for other systems as well during the system design phase to find the appropriate solution satisfying the majority of the requirements, giving a priority to the ones with highly ranked dependencies and hence facilitating the implementation phase and afterward the production line. The outcomes may be used as a step in developing a model-driven approach which should be able to support the manufacturing process, facilitating the integration of systems and software modeling, which is increasingly important for robotic systems in smart factories incorporating HRC.

Article
Urban environments are urgently required to become smarter to overcome sustainability and resilience challenges whilst remaining economically viable. This involves a vast increase in the penetration of ICT resources, both physical and virtual, with the requirement to factor in built environment, socio-economic and human artefacts. This paper, therefore, proposes a methodology for eliciting, testing, and deploying, requirements in the field of urban cybernetics. This extends best practice requirements engineering principles to meet the demands of this growing niche. The paper follows a case study approach of applying the methodology in the smart water domain, where it achieves positive results. The approach not only heavily utilises iteration alongside domain experts, but also mandates the integration of technical domain experts to ensure software requirements are met. A key novelty of the approach is prioritising a balance between (a) knowledge engineers’ tenacity for logical accuracy, (b) software engineers’ need for speed, simplicity, and integration with other components, and (c) the domain experts’ needs to invoke ownership and hence nurture adoption of the resulting ontology.

Article
Modeling of natural language requirements, especially for a large system, can take a significant amount of effort and time. Many automated model-driven approaches partially address this problem. However, the application of state-of-the-art neural network architectures to automated model element identification tasks has not been studied. In this paper, we perform an empirical study on automatic model elements identification for component state transition models from use case documents. We analyzed four different neural network architectures: feed forward neural network, convolutional neural network, recurrent neural network (RNN) with long short-term memory, and RNN with gated recurrent unit (GRU), and the trade-offs among them using six use case documents. We analyzed the effect of factors such as types of splitting, types of predictions, types of designs, and types of annotations on performance of neural networks. The results of neural networks on the test and unseen data showed that RNN with GRU is the most effective neural network architecture. However, the factors that result in effective predictions of neural networks are dependent on the type of the model element.

Article
The design of data warehouses (DWs) is based on both their data sources and users’ requirements. The more closely the DW multidimensional schema reflects the stakeholders’ needs, the more effectively they will make use of the DW content for their OLAP analyses. Thus, considerable attention has been given in the literature to DW requirements analysis, including requirements elicitation, specification and validation. Unfortunately, traditional approaches are based on complex formalisms that cannot be used with decision makers who have no previous experience with DWs and OLAP. This forces a sharp separation between elicitation and specification. To cope with this problem, we propose a new requirements analysis process where pivot tables, a well-known representation for multidimensional data often used by decision makers, are enhanced to be used both for elicitation and as a specification formalism. A pivot table is a two-dimensional spreadsheet that supports the analyses of multidimensional data by nesting several dimensions on the x- or y-axis and displaying data on multiple pages. The requirements analysis process we propose is iterative and relies on both unstructured and structured interviews; particular attention is given to enable the design of irregular multidimensional schemata, which are often present in real-world DWs but can hardly be understood by unskilled users. Finally, we validate our proposal using a real case study in the biodiversity domain.

Article
The research in this paper adds to the discussion linked to the challenge of capturing and modeling tacit knowledge throughout software development projects. The issue emerged when modeling functional requirements during a project for a client. However, using the design science research methodology at a particular point in the project helped to create an artifact, a functional requirements modeling technique, that resolved the issue with tacit knowledge. Accordingly, this paper includes research based upon the stages of the design science research methodology to design and test the artifact in an observable situation, empirically grounding the research undertaken. An integral component of the design science research methodology, the knowledge base, assimilated structuration and semiotic theories so that other researchers can test the validity of the artifact created. First, structuration theory helped to identify how tacit knowledge is communicated and can be understood when modeling functional requirements for new software. Second, structuration theory prescribed the application of semiotics which facilitated the development of the artifact. Additionally, following the stages of the design science research methodology and associated tasks allows the research to be reproduced in other software development contexts. As a positive outcome, using the functional requirements modeling technique created, specifically for obtaining tacit knowledge on the software development project, indicates that using such knowledge increases the likelihood of deploying software successfully.

Article
Telos is a conceptual modeling language intended to capture software knowledge, such as software system requirements, domain knowledge, architectures, design decisions and more. To accomplish this, Telos was designed to be extensible in the sense that the concepts used to capture software knowledge can be defined in the language itself, instead of being built-in. This extensibility is accomplished through powerful metamodeling features, which proved very useful for interrelating heterogeneous models from requirements, model-driven software engineering, data integration, ontology engineering, cultural informatics and education. We trace the evolution of ideas and research results in the Telos project from its origins in the late eighties. Our account looks at the semantics of Telos, its various implementations and its applications. We also recount related research by other groups and the cross-influences of ideas thereof. We conclude with lessons learnt. Full paper via ShareIt: https://rdcu.be/b2TMH

Top-cited authors
• Utrecht University
• University of Toronto
• Utrecht University
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• Università degli Studi di Trento