Evaluating two ways of calculating priorities in requirements hierarchies - An experiment on hierarchical cumulative voting

When developing large-scale software systems, there is often a large amount of requirements present, and they often reside on several hierarchical levels. In most cases, not all stated requirements can be implemented into the product due to different constraints, and the requirements must hence be prioritized. As requirements on different abstraction levels shall not be compared, prioritization techniques that are able to handle multi-level prioritization are needed. Different such techniques exist, but they seem to result in unfair comparisons when a hierarchy is unbalanced. In this paper, an empirical experiment is presented where an approach that compensate for this challenge is evaluated. The results indicate that some form of compensation is preferred, and that the subjects’ preference is not influenced by the amount of information given.     

Specifications in Context: Stakeholders, Systems and Modelling of Conflict

This paper looks from an ethnographic viewpoint at the case of two information systems in a multinational engineering consultancy. It proposes using the rich findings from ethnographic analysis during requirements discovery. The paper shows how context – organisational and social – can be taken into account during an information system development process. Socio-technical approaches are holistic in nature and provide opportunities to produce information systems utilising social science insights, computer science technical competence and psychological approaches. These approaches provide fact-finding methods that are appropriate to system participants’ and organisational stakeholders’ needs.  The paper recommends a method of modelling that results in a computerised information system data model that reflects the conflicting and competing data and multiple perspectives of participants and stakeholders, and that improves interactivity and conflict management.     

Requirements Management: A Cinderella Story

Why do the business requirements and the final software product often have little in common? Why are stakeholders, developers and managers reluctant to embrace a full requirements process? Why does everybody say, ‘We don’t have time for requirements’? Why is the potentially most beneficial part of the development process ignored or short-changed?  Following are some observations about why the real requirements for the product often go undiscovered. We will address this by focusing on the different concerns of the people involved in requirements.     

Requirements Validation: Execution of UML Models with CPN Tools

Requirements validation is a critical task in any engineering project. The confrontation of stakeholders with static requirements models is not enough, since stakeholders with non-computer science education are not able to discover all the inter-dependencies between the elicited requirements. Even with simple unified modelling language (UML) requirements models, it is not easy for the development team to get confidence on the stakeholders’ requirements validation. This paper describes an approach, based on the construction of executable interactive prototypes, to support the validation of workflow requirements, where the system to be built must explicitly support the interaction between people within a pervasive cooperative workflow execution. A case study from a real project is used to illustrate the proposed approach. This work has been supported by projects uPAIN (AdI/IDEIA/70/2004/3.1B/00364/007) and STACOS (FCT/POSI/CHS/48875/2002).     

A systematic literature review of software requirements prioritization research

ContextDuring requirements engineering, prioritization is performed to grade or rank requirements in their order of importance and subsequent implementation releases. It is a major step taken in making crucial decisions so as to increase the economic value of a system.ObjectiveThe purpose of this study is to identify and analyze existing prioritization techniques in the context of the formulated research questions.MethodSearch terms with relevant keywords were used to identify primary studies that relate requirements prioritization classified under journal articles, conference papers, workshops, symposiums, book chapters and IEEE bulletins.Results73 Primary studies were selected from the search processes. Out of these studies; 13 were journal articles, 35 were conference papers and 8 were workshop papers. Furthermore, contributions from symposiums as well as IEEE bulletins were 2 each while the total number of book chapters amounted to 13.ConclusionPrioritization has been significantly discussed in the requirements engineering domain. However, it was generally discovered that, existing prioritization techniques suffer from a number of limitations which includes: lack of scalability, methods of dealing with rank updates during requirements evolution, coordination among stakeholders and requirements dependency issues. Also, the applicability of existing techniques in complex and real setting has not been reported yet.     

Investigating the penalty reward calculus of software users and its impact on requirements prioritization

ContextThe current requirements engineering techniques for prioritization of software requirements implicitly assume that each user requirement will have an independent and symmetric impact on user satisfaction. For example, it is assumed that implementing a high priority user requirement will positively impact his satisfaction and not implementing a high priority user requirement will negatively impact his satisfaction. Further, the impacts of implementing multiple user requirements on his satisfaction are expected to be additive. But is this always the case?ObjectiveThis paper empirically examines whether the assumptions of symmetric and multiplicative impacts of user requirements on his satisfaction are valid. Further, the study assesses the relative efficacy of 5 methods of requirements prioritization in managing these effects as reflected by the user satisfaction with the prioritized requirement sets.MethodTo test for existence and mitigation of asymmetric effects an adaptation of the widely accepted PRCA (Penalty Reward Contrast Analysis) method was used for 5 requirements prioritization techniques. To test for existence and mitigation of multiplicative effects MHMR (Moderated Hierarchical Multiple Regression) a well-accepted technique for testing interaction effects was used.ResultsBoth asymmetric and multiplicative effects of software requirements on user satisfaction were observed for requirements prioritized using all 5 requirements prioritization methods raising questions about the efficacy of present day requirements prioritization techniques. Further, the results of the experiment led to proposing a new method for requirements prioritization for managing these effects.ConclusionThe study empirically demonstrates the complexities of prioritizing software requirements and calls for a new generation of methods to address them. Understanding and resolving these complexities will enable software providers to conserve resources by enabling them to parsimoniously selecting only those requirements for implementation in the software product that have maximum incremental impact on user satisfaction.     

Experiments with test case prioritization using relevant slices

Software testing and retesting occurs continuously during the software development lifecycle to detect errors as early as possible and to gain confidence that changes to software do not introduce defects. Once developed, test suites are reused and updated frequently, and their sizes grow as software evolves. Due to time and resource constraints, an important goal during regression testing of software is to prioritize the execution of test cases in a suite so as to improve the chances of increasing the rate of fault detection. Prior techniques for test case prioritization are based on the total number of coverage requirements exercised by the test cases. In this paper, we present a new approach to prioritize test cases that takes into account the coverage requirements present in the relevant slices of the outputs of test cases. We have implemented three different heuristics based on our relevant slicing based approach to prioritize test cases and conducted experiments to compare the effectiveness of our techniques with those of the traditional techniques that only account for the total requirement coverage. Our detailed experimental study and results provide interesting insights into the effectiveness of using relevant slices for test case prioritization in terms of ability to achieve high rate of fault detection.     

Priority scheduling service for E-commerce web servers

Service scheduling is one of the crucial issues in E-commerce environment. E-commerce web servers often get overloaded as they have to deal with a large number of customers’ requests—for example, browse, search, and pay, in order to make purchases or to get product information from E-commerce web sites. In this paper, we propose a new approach in order to effectively handle high traffic load and to improve web server’s performance. Our solution is to exploit networking techniques and to classify customers’ requests into different classes such that some requests are prioritised over others. We contend that such classification is financially beneficial to E-commerce services as in these services some requests are more valuable than others. For instance, the processing of “browse” request should get less priority than “payment” request as the latter is considered to be more valuable to the service provider. Our approach analyses the arrival process of distinct requests and employs a priority scheduling service at the network nodes that gives preferential treatment to high priority requests. The proposed approach is tested through various experiments which show significant decrease in the response time of high priority requests. This also reduces the probability of dropping high priority requests by a web server and thus enabling service providers to generate more revenue.     

Modeling stakeholders for information systems design processes

In the software engineering area, stakeholders play a significant role in requirements elicitation and validation. Moreover, all the project management is integrally affected by stakeholders’ perspectives and their participation. This effect is strengthened when projects involve several organizations. Thus, a clear and explicit representation of the stakeholders and their attributes is required in order to achieve their effective management. The integration of this representation with other models capturing the knowledge of engineering design processes can be of great utility in software development projects. In this sense, this article describes the construction of an integrated model for representing stakeholders in information systems design processes. This proposal considers diverse attributes related to stakeholders and gives information for performing quantitative calculations about their interest and influence over the project. Thus, more inclusive experiences of the information systems development can be supported, even more if contexts with the participation of several organizations are considered.     

Risk-based test case prioritization using a fuzzy expert system

Context: The use of system requirements and their risks enables software testers to identify more important test cases that can reveal the faults associated with system components.Objective: The goal of this research is to make the requirements risk estimation process more systematic and precise by reducing subjectivity using a fuzzy expert system. Further, we provide empirical results that show that our proposed approach can improve the effectiveness of test case prioritization.Method: In this research, we used requirements modification status, complexity, security, and size of the software requirements as risk indicators and employed a fuzzy expert system to estimate the requirements risks. Further, we employed a semi-automated process to gather the required data for our approach and to make the risk estimation process less subjective.Results: The results of our study indicated that the prioritized tests based on our new approach can detect faults early, and also the approach can be effective at finding more faults earlier in the high-risk system components compared to the control techniques.Conclusion: We proposed an enhanced risk-based test case prioritization approach that estimates requirements risks systematically with a fuzzy expert system. With the proposed approach, testers can detect more faults earlier than with other control techniques. Further, the proposed semi-automated, systematic approach can easily be applied to industrial applications and can help improve regression testing effectiveness.