Analyzing evolution of variability in a software product line: From contexts and requirements to features

Context

In the long run, features of a software product line (SPL) evolve with respect to changes in stakeholder requirements and system contexts. Neither domain engineering nor requirements engineering handles such co-evolution of requirements and contexts explicitly, making it especially hard to reason about the impact of co-changes in complex scenarios.

Objective

In this paper, we propose a problem-oriented and value-based analysis method for variability evolution analysis. The method takes into account both kinds of changes (requirements and contexts) during the life of an evolving software product line.

Method

The proposed method extends the core requirements engineering ontology with the notions to represent variability-intensive problem decomposition and evolution. On the basis of problemorientation, the analysis method identifies candidate changes, detects influenced features, and evaluates their contributions to the value of the SPL.

Results and Conclusion

The process of applying the analysis method is illustrated using a concrete case study of an evolving enterprise software system, which has confirmed that tracing back to requirements and contextual changes is an effective way to understand the evolution of variability in the software product line.     

Design guidelines for software processes knowledge repository development

Context

Staff turnover in organizations is an important issue that should be taken into account mainly for two reasons:

1.

Employees carry an organization’s knowledge in their heads and take it with them wherever they go

2.

Knowledge accessibility is limited to the amount of knowledge employees want to share

Objective

The aim of this work is to provide a set of guidelines to develop knowledge-based Process Asset Libraries (PAL) to store software engineering best practices, implemented as a wiki.

Method

Fieldwork was carried out in a 2-year training course in agile development. This was validated in two phases (with and without PAL), which were subdivided into two stages: Training and Project.

Results

The study demonstrates that, on the one hand, the learning process can be facilitated using PAL to transfer software process knowledge, and on the other hand, products were developed by junior software engineers with a greater degree of independence.

Conclusion

PAL, as a knowledge repository, helps software engineers to learn about development processes and improves the use of agile processes.     

Conceptual scheduling model and optimized release scheduling for agile environments

Context

Release scheduling deals with the selection and assignment of deliverable features to a sequence of consecutive product deliveries while several constraints are fulfilled. Although agile software development represents a major approach to software engineering, there is no well-established conceptual definition and sound methodological support of agile release scheduling.

Objective

To propose a solution, we present, (1) a conceptual model for agile scheduling, and (2) a novel multiple knapsack-based optimization model with (3) a branch-and-bound optimization algorithm for agile release scheduling.

Method

To evaluate our model simulations were carried out seven real life and several generated data sets.

Results

The developed algorithm strives to prevent resource overload and resource underload, and mitigates risks of delivery slippage.

Conclusion

The results of the experiment suggest that this approach can provide optimized semi-automatic release schedule generations and more informed and established decisions utilizing what-if-analysis on the fly to tailor the best schedule for the specific project context.     

A method for assessing confidence in requirements analysis

Context

During development managers, analysts and designers often need to know whether enough requirements analysis work has been done and whether or not it is safe to proceed to the design stage.

Objective

This paper describes a new, simple and practical method for assessing our confidence in a set of requirements.

Method

We identified four confidence factors and used a goal oriented framework with a simple ordinal scale to develop a method for assessing confidence. We illustrate the method and show how it has been applied to a real systems development project.

Results

We show how assessing confidence in the requirements could have revealed problems in this project earlier and so saved both time and money.

Conclusion

Our meta-level assessment of requirements provides a practical and pragmatic method that can prove useful to managers, analysts and designers who need to know when sufficient requirements analysis has been performed.     

Drivers of agile software development use: Dialectic interplay between benefits and hindrances

Context

Agile software development with its emphasis on producing working code through frequent releases, extensive client interactions and iterative development has emerged as an alternative to traditional plan-based software development methods. While a number of case studies have provided insights into the use and consequences of agile, few empirical studies have examined the factors that drive the adoption and use of agile.

Objective

We draw on intention-based theories and a dialectic perspective to identify factors driving the use of agile practices among adopters of this software development methodology.

Method

Data for the study was gathered through an anonymous online survey of software development professionals. We requested participation from members of a selected list of online discussion groups, and received 98 responses.

Results

Our analyses reveal that subjective norm and training play a significant role in influencing software developers’ use of agile processes and methods, while perceived benefits and perceived limitations are not primary drivers of agile use among adopters. Interestingly, perceived benefit emerges as a significant predictor of agile use only if adopters face hindrances to their agile practices.

Conclusion

We conclude that research in the adoption of software development innovations should examine the effects of both enabling and detracting factors and the interactions between them. Since training, subjective norm, and the interplay between perceived benefits and perceived hindrances appear to be key factors influencing the adoption of agile methods, researchers can focus on how to (a) perform training on agile methods more effectively, (b) facilitate the dialog between developers and managers about perceived benefits and hindrances, and (c) capitalize on subjective norm to publicize the benefits of agile methods within an organization. Further, when managing the transition to new software development methods, we recommend that practitioners adapt their strategies and tactics contingent on the extent of perceived hindrances to the change.     

An ant colony optimization algorithm to improve software quality prediction models: Case of class stability

Context

Assessing software quality at the early stages of the design and development process is very difficult since most of the software quality characteristics are not directly measurable. Nonetheless, they can be derived from other measurable attributes. For this purpose, software quality prediction models have been extensively used. However, building accurate prediction models is hard due to the lack of data in the domain of software engineering. As a result, the prediction models built on one data set show a significant deterioration of their accuracy when they are used to classify new, unseen data.

Objective

The objective of this paper is to present an approach that optimizes the accuracy of software quality predictive models when used to classify new data.

Method

This paper presents an adaptive approach that takes already built predictive models and adapts them (one at a time) to new data. We use an ant colony optimization algorithm in the adaptation process. The approach is validated on stability of classes in object-oriented software systems and can easily be used for any other software quality characteristic. It can also be easily extended to work with software quality predictive problems involving more than two classification labels.

Results

Results show that our approach out-performs the machine learning algorithm C4.5 as well as random guessing. It also preserves the expressiveness of the models which provide not only the classification label but also guidelines to attain it.

Conclusion

Our approach is an adaptive one that can be seen as taking predictive models that have already been built from common domain data and adapting them to context-specific data. This is suitable for the domain of software quality since the data is very scarce and hence predictive models built from one data set is hard to generalize and reuse on new data.     

Beyond the customer: Opening the agile systems development process

Context

A particular strength of agile systems development approaches is that they encourage a move away from ‘introverted’ development, involving the customer in all areas of development, leading to more innovative and hence more valuable information system. However, a move toward open innovation requires a focus that goes beyond a single customer representative, involving a broader range of stakeholders, both inside and outside the organisation in a continuous, systematic way.

Objective

This paper provides an in-depth discussion of the applicability and implications of open innovation in an agile environment.

Method

We draw on two illustrative cases from industry.

Results

We highlight some distinct problems that arose when two project teams tried to combine agile and open innovation principles. For example, openness is often compromised by a perceived competitive element and lack of transparency between business units. In addition, minimal documentation often reduce effective knowledge transfer while the use of short iterations, stand-up meetings and presence of on-site customer reduce the amount of time for sharing ideas outside the team.

Conclusion

A clear understanding of the inter- and intra-organisational applicability and implications of open innovation in agile systems development is required to address key challenges for research and practice.     

Comparing the performance of metaheuristics for the analysis of multi-stakeholder tradeoffs in requirements optimisation

Context

In requirements engineering, there will be many different stake holders. Often the requirements engineer has to find a set of requirements that reflect the needs of several different stake holders, while remaining within budget.

Objective

This paper introduces an optimisation-based approach to the automated analysis of requirements assignments when multiple stake holders are to be satisfied by a single choice of requirements.

Method

The paper reports on experiments using two different multi-objective evolutionary optimisation algorithms with real world data sets as well as synthetic data sets. This empirical validation includes a statistical analysis of the performance of the two algorithms.

Results

The results reveal that the Two-Archive algorithm outperformed the others in convergence as the scale of problems increase. The paper also shows how both traditional and animated Kiviat diagrams can be used to visualise the tensions between the stake holders’ competing requirements in the presence of increasing budgetary pressure.

Conclusion

This paper presented the concept of internal tensioning among multi-stakeholder in requirements analysis and optimisation for the first time. This analysis may be useful in internal negotiations over budgetary allowance for the project.     

Reconciling software development models: A quasi-systematic review

Purpose

The purpose of this paper is to characterize reconciliation among the plan-driven, agile, and free/open source software models of software development.

Design/methodology/approach

An automated quasi-systematic review identified 42 papers, which were then analyzed.

Findings

The main findings are: there exist distinct - organization, group and process - levels of reconciliation; few studies deal with reconciliation among the three models of development; a significant amount of work addresses reconciliation between plan-driven and agile development; several large organizations (such as Microsoft, Motorola, and Philips) are interested in trying to combine these models; and reconciliation among software development models is still an open issue, since it is an emerging area and research on most proposals is at an early stage.

Research limitations

Automated searches may not capture relevant papers in publications that are not indexed. Other data sources not amenable to execution of the protocol were not used. Data extraction was performed by only one researcher, which may increase the risk of threats to internal validity.

Implications

This characterization is important for practitioners wanting to be current with the state of research. This review will also assist the scientific community working with software development processes to build a common understanding of the challenges that must be faced, and to identify areas where research is lacking. Finally, the results will be useful to software industry that is calling for solutions in this area.

Originality/value

There is no other systematic review on this subject, and reconciliation among software development models is an emerging area. This study helps to identify and consolidate the work done so far and to guide future research. The conclusions are an important step towards expanding the body of knowledge in the field.     

Exploring a Bayesian and linear approach to requirements traceability

Context

For large software projects it is important to have some traceability between artefacts from different phases (e.g.requirements, designs, code), and between artefacts and the involved developers. However, if the capturing of traceability information during the project is felt as laborious to developers, they will often be sloppy in registering the relevant traceability links so that the information is incomplete. This makes automated tool-based collection of traceability links a tempting alternative, but this has the opposite challenge of generating too many potential trace relationships, not all of which are equally relevant.

Objective

This paper evaluates how to rank such auto-generated trace relationships.

Method

We present two approaches for such a ranking: a Bayesian technique and a linear inference technique. Both techniques depend on the interaction event trails left behind by collaborating developers while working within a development tool.

Results

The outcome of a preliminary study suggest the advantage of the linear approach, we also explore the challenges and potentials of the two techniques.

Conclusion

The advantage of the two techniques is that they can be used to provide traceability insights that are contextual and would have been much more difficult to capture manually. We also present some key lessons learnt during this research.     

Pattern-based framework for modularized software development and evolution robustness

Context

Software development is now facing much more challenges than ever before due to the intrinsic high complexity and the increasing demands of the quick-service-ready paradigm.

Objective

As the developers are now called for more quality software systems from the industries, there is insufficient guidance from the methodologies and standards of software engineering that can provide assistance to the rapid development of qualified business software.

Method

In this work, we discuss the advantages of the pattern-based software development. We verify the benefits using a pattern-based software framework called OS2F, and a corresponding system design architecture that is intended for the rapid development of web applications.

Results

The objective of the framework/architecture is that, through software patterns, developers should be able to separate the work of system development from the business rules so as to reduce the problems caused by a developer’s lack of business experiences.

Conclusion

Through a suitable pattern-based software framework, the quality of the product can thus be enhanced, software development time and cost decreased, and software evolution robustness improved.     

On the relationship of concern metrics and requirements maintainability

Context

Maintainability has become one of the most essential attributes of software quality, as software maintenance has shown to be one of the most costly and time-consuming tasks of software development. Many studies reveal that maintainability is not often a major consideration in requirements and design stages, and software maintenance costs may be reduced by a more controlled design early in the software life cycle. Several problem factors have been identified as harmful for software maintainability, such as lack of upfront consideration of proper modularity choices. In that sense, the presence of crosscutting concerns is one of such modularity anomalies that possibly exert negative effects on software maintainability. However, to the date there is little or no knowledge about how characteristics of crosscutting concerns, observable in early artefacts, are correlated with maintainability.

Objective

In this setting, this paper introduces an empirical analysis where the correlation between crosscutting properties and two ISO/IEC 9126 maintainability attributes, namely changeability and stability, is presented.

Method

This correlation is based on the utilization of a set of concern metrics that allows the quantification of crosscutting, scattering and tangling.

Results

Our study confirms that a change in a crosscutting concern is more difficult to be accomplished and that artefacts addressing crosscutting concerns are found to be less stable later as the system evolves. Moreover, our empirical analysis reveals that crosscutting properties introduce non-syntactic dependencies between software artefacts, thereby decreasing the quality of software in terms of changeability and stability as well. These subtle dependencies cannot be easily detected without the use of concern metrics.

Conclusion

The correlation provides evidence that the presence of certain crosscutting properties negatively affects to changeability and stability. The whole analysis is performed using as target cases three software product lines, where maintainability properties are of upmost importance not only for individual products but also for the core architecture of the product line.     

Software engineering projects may fail before they are started: Post-mortem analysis of five cancelled projects

Context

Software project cancellations are often caused by mistakes made during the project, and such cancellations make a strong economic impact. We analyzed five cancelled software engineering projects. One case was an internal product development project of a company that sells products to its customers. The other four cases were different software engineering projects, and outcomes of these projects were planned to be delivered to external customers.

Objective

This study reports a post-mortem analysis of five software engineering projects with the aim of providing more knowledge about the reasons for cancellation decisions and the causes behind those reasons.

Methods

The research method is case study. A method for a document-based post-mortem analysis was developed and post-mortem analysis was performed. All project documentation was available for analysis.

Results

The reasons for the cancellation decisions were well-known ones. In four cases of five, the outcome of the project was to be delivered to an external customer, but in these cases the causes of the cancellation reasons were not found from the normal project documentation. In these cases the cause of the cancellation originated in a phase before the start of the project and therefore the project was doomed before it was started.

Conclusion

It is reasonable to suggest that a remarkable portion of project cancellations are due to mistakes made before the project is started in the case of contract-based software engineering projects.     

Post-agility: What follows a decade of agility?

Context

Agile information systems development (ISD) has received much attention from both the practitioner and researcher community over the last 10-15 years. However, it is still unclear what precisely constitutes agile ISD.

Objective

Based on four empirical studies conducted over a 10-year time period from 1999 to 2008 the objective of this paper is to show how the meaning and practice of agile ISD has evolved over time and on this basis to speculate about what comes next.

Method

Four phases of research has been conducted, using a grounded theory approach. For each research phase qualitative interviews were held in American and/or Danish companies and a grounded theory was inductively discovered by careful data analysis. Subsequently, the four unique theories have been analyzed for common themes, and a global theory was identified across the empirical data.

Results

In 1999 companies were developing software at high-speed in a desperate rush to be first-to-market. In 2001 a new high-speed/quick results development process had become established practice. In 2003 changes in the market created the need for a more balanced view on speed and quality, and in 2008 companies were successfully combining agile and plan-driven approaches to achieve the benefits of both. The studies reveal a two-stage pattern in which dramatic changes in the market causes disruption of established practices and process adaptations followed by consolidation of lessons learnt into a once again stable software development process.

Conclusion

The cyclical history of punctuated process evolution makes it possible to distinguish pre-agility from current practices (agility), and on this basis, to speculate about post-agility: a possible next cycle of software process evolution concerned with proactively pursuing the dual goal of agility and alignment through a diversity of means.     

Path dependent stochastic models to detect planned and actual technology use: A case study of OpenOffice

Context

Adopting IT innovation in organizations is a complex decision process driven by technical, social and economic issues. Thus, those organizations that decide to adopt innovation take a decision of uncertain success of implementation, as the actual use of a new technology might not be the one expected. The misalignment between planned and effective use of innovation is called assimilation gap.

Objective

This research aims at defining a quantitative instrument for measuring the assimilation gap and applying it to the case of the adoption of OSS.

Method

In this paper, we use the theory of path dependence and increasing returns of Arthur. In particular, we model the use of software applications (planned or actual) by stochastic processes defined by the daily amounts of files created with the applications. We quantify the assimilation gap by comparing the resulting models by measures of proximity.

Results

We apply and validate our method to a real case study of introduction of OpenOffice. We have found a gap between the planned and the effective use despite well-defined directives to use the new OS technology. These findings suggest a need of strategy re-calibration that takes into account environmental factors and individual attitudes.

Conclusions

The theory of path dependence is a valid instrument to model the assimilation gap provided information on strategy toward innovation and quantitative data on actual use are available.     

Agile methods rapidly replacing traditional methods at Nokia: A survey of opinions on agile transformation

Context

Many organizations have started to deploy agile methods, but so far there exist only a few studies on organization-wide transformations. Are agile methods here to stay? Some claim that agile software development methods are in the mainstream adoption phase in the software industry, while others hope that those are a passing fad. The assumption here is that if agile would not provide real improvement, adopters would be eager at first but turn pessimistic after putting it into practice.

Objective

Despite the growing amount of anecdotal evidence on the success of agile methods across a wide range of different real-life development settings, scientific studies remain scarce. Even less is known about the perception of the impacts of agile transformation when it is deployed in a very large software development environment, and whether agile methods are here to stay. This study aims to fill that gap by providing evidence from a large-scale agile transformation within Nokia. While we have yet to confirm these findings with solid quantitative data, we believe that the perception of the impacts already pinpoints the direction of the impacts of large-scale agile transformation.

Method

The data were collected using a questionnaire. The population of the study contains more than 1000 respondents in seven different countries in Europe, North America, and Asia.

Results

The results reveal that most respondents agree on all accounts with the generally claimed benefits of agile methods. These benefits include higher satisfaction, a feeling of effectiveness, increased quality and transparency, increased autonomy and happiness, and earlier detection of defects. Finally, 60% of respondents would not like to return to the old way of working.

Conclusion

While the perception of the impact of agile methods is predominantly positive, several challenge areas were discovered. However, based on this study, agile methods are here to stay.     

Research synthesis in software engineering: A tertiary study

Context

Comparing and contrasting evidence from multiple studies is necessary to build knowledge and reach conclusions about the empirical support for a phenomenon. Therefore, research synthesis is at the center of the scientific enterprise in the software engineering discipline.

Objective

The objective of this article is to contribute to a better understanding of the challenges in synthesizing software engineering research and their implications for the progress of research and practice.

Method

A tertiary study of journal articles and full proceedings papers from the inception of evidence-based software engineering was performed to assess the types and methods of research synthesis in systematic reviews in software engineering.

Results

As many as half of the 49 reviews included in the study did not contain any synthesis. Of the studies that did contain synthesis, two thirds performed a narrative or a thematic synthesis. Only a few studies adequately demonstrated a robust, academic approach to research synthesis.

Conclusion

We concluded that, despite the focus on systematic reviews, there is limited attention paid to research synthesis in software engineering. This trend needs to change and a repertoire of synthesis methods needs to be an integral part of systematic reviews to increase their significance and utility for research and practice.     

A systematic review of software architecture evolution research

Context

Software evolvability describes a software system’s ability to easily accommodate future changes. It is a fundamental characteristic for making strategic decisions, and increasing economic value of software. For long-lived systems, there is a need to address evolvability explicitly during the entire software lifecycle in order to prolong the productive lifetime of software systems. For this reason, many research studies have been proposed in this area both by researchers and industry practitioners. These studies comprise a spectrum of particular techniques and practices, covering various activities in software lifecycle. However, no systematic review has been conducted previously to provide an extensive overview of software architecture evolvability research.

Objective

In this work, we present such a systematic review of architecting for software evolvability. The objective of this review is to obtain an overview of the existing approaches in analyzing and improving software evolvability at architectural level, and investigate impacts on research and practice.

Method

The identification of the primary studies in this review was based on a pre-defined search strategy and a multi-step selection process.

Results

Based on research topics in these studies, we have identified five main categories of themes: (i) techniques supporting quality consideration during software architecture design, (ii) architectural quality evaluation, (iii) economic valuation, (iv) architectural knowledge management, and (v) modeling techniques. A comprehensive overview of these categories and related studies is presented.

Conclusion

The findings of this review also reveal suggestions for further research and practice, such as (i) it is necessary to establish a theoretical foundation for software evolution research due to the fact that the expertise in this area is still built on the basis of case studies instead of generalized knowledge; (ii) it is necessary to combine appropriate techniques to address the multifaceted perspectives of software evolvability due to the fact that each technique has its specific focus and context for which it is appropriate in the entire software lifecycle.     

The value of software sizing

Context

One of the difficulties faced by software development Project Managers is estimating the cost and schedule for new projects. Previous industry surveys have concluded that software size and cost estimation is a significant technical area of concern. In order to estimate cost and schedule it is important to have a good understanding of the size of the software product to be developed. There are a number of techniques used to derive software size, with function points being amongst the most documented.

Objective

In this paper we explore the utility of function point software sizing techniques when applied to two levels of software requirements documentation in a commercial software development organisation. The goal of the research is to appraise the value (cost/benefit) which functional sizing techniques can bring to the project planning and management of software projects within a small-to-medium sized software development enterprise (SME).

Method

Functional counts were made at the bid and detailed functional specification stages for each of five commercial projects used in the research. Three variants of the NESMA method were used to determine these function counts. Through a structured interview session, feedback on the sizing results was obtained to evaluate its feasibility and potential future contribution to the company.

Results

The results of our research suggest there is value in performing size estimates at two appropriate stages in the software development lifecycle, with simplified methods providing the optimal return on effort expended.

Conclusion

The ‘Estimated NESMA’ is the most appropriate tool for use in size estimation for the company studied. The use of software sizing provides a valuable contribution which would augment, but not replace, the company’s existing cost estimation approach.     

Formal model for assigning human resources to teams in software projects

Context

Human resources play a critical role in software project success. However, people are still the least formalized factor in today’s process models. Generally, people are assigned to roles and project teams are formed on the basis of project leaders’ experience of people, constraints (e.g. availability) and skill requirements. Yet this process has to take multiple factors into account. Few works in the literature model this process. Most of these are informal proposals focusing on the individual assignment of people to project tasks and do not consider other aspects like team formation as a whole.

Objective

In this paper we formulate a formal model for assigning human resources to software project teams. Additionally, we describe the key results of the knowledge management process enacted to output the elements of the model.

Method

The model elements were identified using the Delphi expert consultation method and applying psychological tests. The proposed model was implemented in a software tool and validated on two software development organization assignment scenarios.

Results

We built a formal model for the process of assigning human resources to software project teams. This model takes into account as many factors as possible and aids the assignment of individuals to project roles, as well as the formation of the team as a whole.We found that the rules that were identified to form software development project teams are useful. From the tests we found that model implementation was feasible (all the executions of the implemented problem-solving algorithms output feasible solutions in response times that can be considered as acceptable).

Conclusion

Using the Delphi method we were able to propose software project roles and competences. Psychological tests and data mining tools identified useful rules for forming software project teams. These were used to build a formal model. This model was built into a tool that returns role assignments in acceptable response times. This decision support tool helps managers assign people to roles and to form teams. Using the tool, project leaders can flexibly evaluate different team make-ups, taking into account several factors, as well as different constraints and objectives.