Requirements engineering for crossover services: Issues, challenges and research directions

IET SoftwareVolume 15, Issue 1 p. 107-125 ORIGINAL RESEARCH PAPEROpen Access Requirements engineering for crossover services: Issues, challenges and research directions Zhengli Liu, Zhengli Liu School of Computer Science, Wuhan University, Wuhan, ChinaSearch for more papers by this authorBing Li, Corresponding Author Bing Li bingli@whu.edu.cn School of Computer Science, Wuhan University, Wuhan, China Correspondence Bing Li and Jian Wang, School of Computer Science, Wuhan University, Wuhan, China. Email: bingli@whu.edu.cn (B. L.) and jianwang@whu.edu.cn (J. W.)Search for more papers by this authorJian Wang, Corresponding Author Jian Wang bingli@whu.edu.cn School of Computer Science, Wuhan University, Wuhan, China Correspondence Bing Li and Jian Wang, School of Computer Science, Wuhan University, Wuhan, China. Email: bingli@whu.edu.cn (B. L.) and jianwang@whu.edu.cn (J. W.)Search for more papers by this authorRong Yang, Rong Yang College of Computer Science and Technology, Hubei University of Science and Technology, Xian 'Ning, ChinaSearch for more papers by this author Zhengli Liu, Zhengli Liu School of Computer Science, Wuhan University, Wuhan, ChinaSearch for more papers by this authorBing Li, Corresponding Author Bing Li bingli@whu.edu.cn School of Computer Science, Wuhan University, Wuhan, China Correspondence Bing Li and Jian Wang, School of Computer Science, Wuhan University, Wuhan, China. Email: bingli@whu.edu.cn (B. L.) and jianwang@whu.edu.cn (J. W.)Search for more papers by this authorJian Wang, Corresponding Author Jian Wang bingli@whu.edu.cn School of Computer Science, Wuhan University, Wuhan, China Correspondence Bing Li and Jian Wang, School of Computer Science, Wuhan University, Wuhan, China. Email: bingli@whu.edu.cn (B. L.) and jianwang@whu.edu.cn (J. W.)Search for more papers by this authorRong Yang, Rong Yang College of Computer Science and Technology, Hubei University of Science and Technology, Xian 'Ning, ChinaSearch for more papers by this author First published: 31 December 2020 https://doi.org/10.1049/sfw2.12014AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Abstract Crossover services involve deep convergence of services in different domains. Requirements analysis of crossover services often requires the collaboration of engineers in different domains and various organizations. The industry has a demand for sophisticated requirements engineering (RE) methods to address challenges brought by crossover and convergence. However, many methods proposed by researchers have not been widely used in the industry, and the reason is that these methods provide technological solutions to the problems and challenges that may not be considered accurate or even real by practitioners in the crossover services industry. A great effort is needed to explore what needs, expectations, and constraints that RE approaches must satisfy and promote the adoption of novel RE approaches in the crossover services industry. The authors have conducted an industrial study to gain an in-depth understanding of practitioners' needs concerning RE research and method development. The study involved qualitative interviews as well as questionnaires to collect data. The objective of this study is to investigate issues, challenges, and practices of crossover services RE from practitioners' perspectives and to reveal potential guidelines for researchers and tools developers. Findings from five aspects of RE methods are reported and some research directions for future crossover services RE research are provided. 1 INTRODUCTION Faced with consumption upgrades and fierce market competition in the Internet era, many enterprises have deeply integrated resources and services in different domains and innovated business models through expanding their business to other industries, thus forming a new business model: crossover service. For example, as one of the largest OTA (Online Travel Agency) service providers in China, Fliggy can provide air ticket booking, hotel booking, and attraction ticket booking services for users. To provide a better travel experience for users with uncertain itineraries and reduce losses caused by cancelling orders, Fliggy has converged insurance services on the basis of hotel reservation services and launched an insurance cancellation service to users when they cancel reservations due to itinerary change or even with no reason, which can greatly improve user experience. Crossover service [1] is defined as an innovation creation process for enterprises to provide users with creative, novel, and cross-domain products/services by breaking through the traditional boundaries of enterprises and domains. Such a service is generally characterised by three basic characteristics: Crossover: Crossover services usually span multiple business and industrial areas and show typical crossover characteristics. Convergence: Services in different fields are deeply converged into a new crossover service. This convergence involves value convergence, quality convergence, data convergence, and process convergence. Complexity: Unlike most classical single-domain-oriented services, crossover services span multiple industry domains and require the integration of heterogeneous resources across multiple domains to meet the needs of users in different domains, which also increases the complexity of development. Despite the advantages of crossover services, enterprises still face huge challenges when migrating to crossover services. Crossover services involve the coordination of multiple organizations and the heterogeneity of different industries and fragmentation of areas which leads to great obstacles to requirements negotiations. Also, there are many stakeholders in crossover service ecosystems, and their goals are different, which are prone to inconsistencies and conflicts in requirements. Moreover, the complexity of crossover services leads to a higher risk of potential errors and defects in requirements specifications, which greatly increases the probability of project failure. Requirements engineering (RE) is critical to the success of crossover services. Fanmuy reported a strong correlation between project performances and RE capabilities; that is, organizations with low capabilities in RE are likely to have poor performance projects and vice versa [2]. To obtain high-quality requirements and reduce development efforts to ensure the success of projects, many researchers have proposed a large number of RE methods from different perspectives, such as goal-based, model-based, scenario-based, and value-based RE methods. However, many methods have not been applied on a large scale in the industry [3]. One possible explanation is that the proposed methods did not consider the real needs of the industry effectively. The starting point of the methods proposed by many researchers is the problems pointed out in the existing literature, but these problems are not consistent with the real needs of the industry [3]. To bridge the gap between academia and industry, researchers and developers of RE tools need to have a deeper understanding of issues and challenges in RE. Although the existing literature provides some insights into the current application of RE in the industry [3-6], as an emerging service mode, RE of crossover services faces enormous challenges, but there is no literature on systematic research on this issue. To investigate and understand the essential issues and challenges, we conducted an industry study guided by the following research question: What are current industry needs concerning methods support for RE in the crossover service domain? This paper aims to conduct empirical research grounded on the recent trends in the crossover services industry and thus to fill the gap between the research conducted by academicians and its implementation undertaken by practitioners. To reveal the RE challenges faced by crossover service companies and gain insights into both academia and industry, we researched five areas related to RE: Use traditional RE methods or require new approaches. Support for value convergence. Quality assurance of requirements specifications. Requirements negotiations across multiple organizations. Support for requirements convergence. To carry out this research, we selected participants from companies that provide crossover services in China. To deeply study the issues and challenges encountered in the industry during the process of crossover service requirements analysis, we designed a questionnaire and conducted in-depth interviews with practitioners to collect important and meaningful data. We consider the empirical study results as particularly useful for the following audience: RE researchers who want to provide new methods for crossover services, RE tool developers who wish to develop new tools or improve existing tools to assist analysts in conducting crossover service RE activities; and decision-makers who want to transfer their services to other domains, that is, to provide crossover services. The remaining sections are structured as follows: Section 2 introduces research questions. Section 3 presents the research methods for our study. In Section 4, key findings of our investigation and evidences that support the key findings are reported. Section 5 discusses some implications and trade-offs, and we put forward some future RE research directions based on the findings. Section 6 introduces related work. Section 7 summarises the paper and discusses future work. 2 MOTIVATIONS As a new emerging industry, only a few literatures focus on RE of crossover services [7, 8], and these studies only provide some methods to model requirements without making an in-depth analysis of industry needs. Therefore, one of the main purposes of our study is to explore real challenges and difficulties faced by the crossover service industry in the requirements analysis process, which can provide new research directions for researchers and guidelines for developers of RE tools. In the following part, we explain the motivation for choosing the five investigation aspects stated in Section 1: Use traditional RE methods or require new methods: In the past years, many researchers proposed many RE methods from different perspectives, such as goal-based methods [9-11], value-based methods [12-14], scenario-based methods [15, 16], and Unified Modeling Language (UML)-based methods [17]. These methods have been widely used in the industry; however, given the characteristics of crossover and convergence, we need to explore whether these traditional methods can still be applied in requirements analysis of crossover services. Furthermore, we are concerned about new RE methods that the industry needs. The exploration of these issues will identify current challenges and problems faced by the crossover services industry and their real needs, which will help researchers to identify new problems and find new research directions, furthermore, this is also useful to close the gap between academia and industry. Support for value convergence: The existing value-based RE methods mainly focus on modeling the value network in specific business scenarios, and the primary purpose is to clarify the value exchange between stakeholders [12, 18]. However, in industry, these modeling methods have not been widely adopted. Some studies have pointed out that value convergence is an important aspect of crossover service [8]. In industry, value modeling of crossover services not only needs to model the value network formed by stakeholders of different domains but also needs to deeply converge value models of different domains to get the final unified value model. Since previous works have neglected practitioners' needs with regard to improved methods for value convergence, we chose this aspect as an investigation focus of our study. Quality assurance of requirements specification: The quality of requirements specification is critical to ensuring the success of software services. Crossover services involve collaborations of different industries and organizations, and domain knowledge in these organizations is different. Besides, the development of requirements specifications often needs collaboration of requirements analysts from multiple organizations, which results in a higher probability of quality problems in the requirements specifications. What's more, potential errors in requirements specifications can lead to rework later, wasting a lot of time and increasing software development costs. Although some studies have focused on ensuring the quality of software specifications, different methods are required for different quality metrics. For crossover services, researchers and tool developers need to know which specific requirements quality metrics need to be improved. So, we investigated which quality criteria for requirements are most challenging in crossover services and hence require improved methods to support. Requirements negotiation across multiple organizations: Crossover services often span multiple business domains, multiple organizations, multiple regions, or even multiple countries. Therefore, the requirements negotiation process needs collaboration and communication among various stakeholders (e.g. requirements engineers, users, product managers, and developers) from different organizations and domains to reach a consensus viewpoint. Therefore, it is necessary to investigate difficulties and challenges faced by the industry in carrying out requirements negotiation activities and identify which new collaboration methods or tools the industry needs to support requirements negotiation tasks. Support for requirements convergence: In the past years, many RE modeling methods [19-21] have been proposed, which mainly focus on the requirements of a particular domain, without considering issues of requirements convergence from multiple domains. Different from requirements negotiations that focus on requirements collaboration activities, requirements convergence mainly covers all the convergence activities of requirements derived from stakeholders of different domains. These requirements convergence activities may involve requirements merging, requirements supplement, and requirements conflict resolution. During the process of requirements convergence, when requirements conflicts occur, requirements negotiation may be triggered to reach an agreement among stakeholders. Thus, requirements negotiation could contribute to the requirements convergence. However, the current research on requirements convergence of crossover service is quite scarce. The exploration of these issues helps identify issues and challenges in the process of requirements convergence of crossover services, so as to provide new research directions for researchers and new ideas for tool developers. 3 RESEARCH METHODOLOGY To comprehensively study the issues and challenges of RE in crossover services, we conduct an exploratory research and use a mixed way to collect data, including participatory observations, semi-structured interviews, and questionnaires. By analyzing the data collected from various channels, we reach our conclusions. 3.1 Participatory observation The first author has practiced for two months in a crossover service company and directly participated in the business scenario analysis and requirements discussion meeting of a crossover service converged by an online travel service and an insurance service. In his daily agenda, he records how the team conducts requirements analysis, such as how the participants in the team and other external teams conduct requirements analysis and how the team ensures the quality of requirements. This in-depth involvement with the development team of crossover services contributes positively to subsequent interviewees selection and questionnaire design. 3.2 Questionnaire To obtain some quantitative data and provide additional evidence to enhance the interpretation of the qualitative data from the interviews, we set up a questionnaire to collect some valuable and meaningful data. Before formulating the questionnaire, we first read some literatures to explore the concerns of the RE field and then built a draft questionnaire with the consideration of characteristics of crossover services. Furthermore, we communicated with practitioners in the industry and corrected the questionnaire according to their feedbacks and suggestions. Note that to avoid research bias, these practitioners did not participate in the follow-up questionnaire and interview. Following the continuous iteration process, the questionnaire was finally constructed (Table 1). The questionnaire consists of 24 items, covering topics of the five investigation aspects stated in Section 2. In the process of questionnaire design, we ensure that different questions in the questionnaire are worded differently, and we avoid using words that could introduce bias in the question. Furthermore, we also invite colleagues to review the questions used in the questionnaire to avoid a possible source of bias. The respondents are requested to complete the questionnaire within seven days. We then process the collected questionnaire results. First of all, the answers to similar opinions are combined. Then, we classify the answers according to the topics and sort out issues, challenges, and practical experience. Finally, we merge the results with the semi-structured interviews. We recruited 20 participants, and only 16 of them answered the questionnaires. During the selection process, we selected participants with different organizational levels and responsibilities in different positions to participate in our interviews. Meanwhile, if practitioners are from the same company, we make sure that they come from different departments or teams. What's more, the recruited practitioners have a good understanding of RE of crossover services and have directly participated in the development of crossover services projects. TABLE 1. Questions in the questionnaire No. Statement 1 Which role do you play in crossover service development? 2 How much experience do you have in RE? 3 What is your familiarity with RE? 4 Which methods do you mainly use during the process of crossover service requirements analysis? 5 Do you think traditional requirements analysis methods can efficiently address the challenges of crossover service? 6 What is the final output format after requirements analysis? 7 Do you classify requirements at different abstraction levels? 8 Which methods do you use to manage the priority of requirements? 9 Do you think that considering value convergence in the requirements analysis stage is helpful for the subsequent service design and development? 10 Which methods do you use to support value convergence in requirements analysis? 11 Do you think current value convergence methods are sufficient? 12 Which methods do you use to deal with conflicts in the process of value convergence? 13 Which methods do you use to evaluate the quality of the requirements specification? 14 Which quality metrics do you think need to be strengthened in the future? 15 Do you often communicate with external participants when you participate in requirements engineering of crossover services? 16 Does crossover bring obstacles to cross-organizational requirements negotiations? 17 How do you communicate with external participants? 18 When do you need to negotiate requirements with external participants, and how do you contact them? 19 Which stakeholders contribute the most requirements? 20 Do you think the existing RE methods are sufficient to support the requirements convergence? 21 Do you think new tools are needed to support requirements convergence? 22 Which methods do you use to address the conflicts caused by requirements convergence? 23 What kinds of functionalities should be offered by new RE methods to handle the challenges of crossover services RE? 24 What kinds of features should be offered by new RE tools to alleviate the challenges of crossover service? Abbreviation: RE, requirements engineering. 3.3 Semi-structured interviews We invite the participants who have participated in the questionnaires to take part in our interviews, including one operational engineer, one department leader, two technical leaders, five product managers, and seven developers, as shown in Figure 1. In the study, we did not pay attention to the gender, age, or nationality of the participants, as these factors did not affect the participants' attitude towards crossover service RE. FIGURE 1Open in figure viewerPowerPoint Answer to statement 1 The interview process follows these guidelines: We introduce the purpose of our interview to the interviewee; We raise some guiding questions to start the interview. These guiding questions come from the questionnaires filled out by the participants, aiming to get more in-depth details about their viewpoints. For example, ① In the questionnaire, I found that your team still uses traditional RE methods. Can they effectively complete the task of crossover service requirements analysis? ② How do you deal with the complexity of requirements due to crossover and convergence? ③ Do you think the existing methods or tools are sufficient to support value convergence? Why? ④ Which methods or tools do you use to address the conflicts caused by value convergence? Why? ⑤ Which methods or tools do you use to ensure the quality of requirements specifications? ⑥ In the process of participating in the crossover services requirements analysis, which metrics of the requirements specifications, do you think need to be strengthened? ⑦ What are the difficulties you are facing during the requirements negotiation of crossover service? ⑧ In your opinion, the existing methods cannot effectively cope with the requirements convergence of crossover service. Why? ⑨ In general, what functions do you think the future RE tools need to provide to better support the task of crossover services requirements analysis? Strict adherence to the interview guiding questions is not enforced. The interviewer should be allowed to respond flexibly to the participants' answers and investigate the topics in the interview in more detail. Furthermore, the interviews are open-ended, and participants are free to express their opinions. Therefore, the guiding questions to different participants may be various. To avoid bias and tendency, we do not use guiding questions that can prompt participants to respond in favour of a particular assumption. For example we use 'which methods do you use' instead of 'do you use xxx method'. If the answers do not sound right, we will ask the question in different ways. Note that directly asking closed questions during the interview might bias participants toward confirmation. To avoid this bias, the participants were independent of each other and were asked open questions, followed by the 'why' question. 3. Interviewees can speak freely and talk about their practice and experience in participating in crossover service requirements analysis; 4. We record what the interviewees said and repeat to them to confirm the accuracy of the content. The whole interview process covers several research issues we are concerned about. After the interview, we sort out all conversation contents and classify the conversation of similar topics together; we then analyze the topics and find out which topics are related to issues and challenges, and which are related to RE practice and experience; and finally, we cross-validate these classified topics to ensure the accuracy of classification. Based on the above analysis, we report the issues and challenges faced by crossover service RE, as well as some major findings. 3.4 Demographic questionnaire To ensure the effectiveness of the conclusions of this study, we design some demographic questionnaire to verify that the participants meet the inclusion criteria of the study. The demographic questionnaire consists of three questions about the professional roles and experience of individual participants with RE. Three-quarters of the participants reported their experience with RE to be between two and five years, and 19% reported more than five years of experience, as shown in Figure 2. FIGURE 2Open in figure viewerPowerPoint Participants' years of experience with requirements engineering (RE) for crossover services (answer to statement 2) In addition, 100% of the participants self-reported their level of experience in RE as familiar, master, or expert, as shown in Figure 3. Our research aimed at revealing the real needs of the crossover service industry. Therefore, research participants are required to be familiar with this field and participate in crossover service RE practice for a long time to assess the current practice and trends therein. Based on the above considerations, we have selected the participants' years of experience rather than 'theoretical knowledge about RE' as the most critical measure of the participants' qualifications. FIGURE 3Open in figure viewerPowerPoint Participants' familiarity with requirements engineering for crossover services (answer to statement 3) 4 KEY FINDINGS AND EVIDENCE In this section, we will list some key findings obtained from the questionnaire and interviews, as well as some existing practical experience in the industry. For each concern, we will first report key findings and then give evidence that supports these findings. We present some future research directions derived from our findings in Section 5. 4.1 Use traditional requirements engineering methods or require new methods In recent years, many RE methods have been proposed and applied in many industry domains; however, faced with new challenges brought by crossover services, whether traditional RE methods can still work is an important focus. 4.1.1 Key findings Finding 1.1: The fact that traditional RE methods are widely used in industry does not imply that they can address the challenges of crossover service requirement analysis, such as cross-organization collaborative requirements modeling and requirements convergence. In fact, many requirements engineers are dissatisfied with traditional RE methods. Finding 1.2: Natural language and prototype systems are the most commonly used types of requirement specifications. Although natural language text is widely used by many companies, practitioners are not satisfied because it is often accompanied by ambiguity and inconsistency. Finding 1.3: Classification of requirements from different abstraction levels is considered to be an effective way to deal with the complexity of RE. However, only a few practitioners report that they use abstraction layers to address requirements complexity. Finding 1.4: Values and core business are major factors that influence requirements priorities in practice. 4.1.2 Evidence Evidence for finding 1.1: In the questionnaire, most participants reported that UML and natural language are the main RE methods (see Figure 4). The reason is that UML is a requirement modeling standard of Object Management Group (OMG), and there are many mature engineering tools to support it, such as IBM Rational Rose and Visio. Besides, role-based and scenario-based methods are also used by many practitioners. Besides, it should be noted that goal-based methods are not widely used in the industry [3]. One of the primary reasons is that many practitioners are not familiar with goal-oriented methods. Also, the majority of the participants reported that existing RE methods were not sufficient to support requirements analysis of crossover services, and only three participants held the opposite opinions (see Figure 5). FIGURE 4Open in figure viewerPowerPoint Answers to statement 4 FIGURE 5Open in figure viewerPowerPoint Answers to statement 5 In the interviews, the practitioners reported that UML was the most widely used requirement modeling method in the industry. Because crossover services involve complex scenarios and many stakeholders, scenario-based and role-based methods are also used by many teams to model user requirements. In addition, several participants reported that their teams adopted goal-based approaches to decompose business goals and allocate them to various departments. Although traditional RE methods are still used for requirements modeling and analysis, this does not mean that they can meet the challenges of crossover services. Although traditional RE methods can model requirements of different domains, they cannot effectively deal with the challenges of requirements convergence. Moreover, the practitioners reported that they have to rely on their personal experience and domain knowledge to achieve the convergence of requirements from different domains manually. During the first author's participation in crossover service projects, several practitioners from a crossover service enterprise stated that traditional UML-based methods such as use case diagrams and sequence diagrams were still used for requirements analysis. In addition, many participants stated that these technologies are very mature, and developers are familiar with them