A systematic review and an expert survey on capabilities supporting multi product lines

ContextComplex software-intensive systems comprise many subsystems that are often based on heterogeneous technological platforms and managed by different organizational units. Multi product lines (MPLs) are an emerging area of research addressing variability management for such large-scale or ultra-large-scale systems. Despite the increasing number of publications addressing MPLs the research area is still quite fragmented.ObjectiveThe aims of this paper are thus to identify, describe, and classify existing approaches supporting MPLs and to increase the understanding of the underlying research issues. Furthermore, the paper aims at defining success-critical capabilities of infrastructures supporting MPLs.MethodUsing a systematic literature review we identify and analyze existing approaches and research issues regarding MPLs. Approaches described in the literature support capabilities needed to define and operate MPLs. We derive capabilities supporting MPLs from the results of the systematic literature review. We validate and refine these capabilities based on a survey among experts from academia and industry.ResultsThe paper discusses key research issues in MPLs and presents basic and advanced capabilities supporting MPLs. We also show examples from research approaches that demonstrate how these capabilities can be realized.ConclusionsWe conclude that approaches supporting MPLs need to consider both technical aspects like structuring large models and defining dependencies between product lines as well as organizational aspects such as distributed modeling and product derivation by multiple stakeholders. The identified capabilities can help to build, enhance, and evaluate MPL approaches.     

Validating a model-driven software architecture evaluation and improvement method: A family of experiments

ContextSoftware architectures should be evaluated during the early stages of software development in order to verify whether the non-functional requirements (NFRs) of the product can be fulfilled. This activity is even more crucial in software product line (SPL) development, since it is also necessary to identify whether the NFRs of a particular product can be achieved by exercising the variation mechanisms provided by the product line architecture or whether additional transformations are required. These issues have motivated us to propose QuaDAI, a method for the derivation, evaluation and improvement of software architectures in model-driven SPL development.ObjectiveWe present in this paper the results of a family of four experiments carried out to empirically validate the evaluation and improvement strategy of QuaDAI.MethodThe family of experiments was carried out by 92 participants: Computer Science Master’s and undergraduate students from Spain and Italy. The goal was to compare the effectiveness, efficiency, perceived ease of use, perceived usefulness and intention to use with regard to participants using the evaluation and improvement strategy of QuaDAI as opposed to the Architecture Tradeoff Analysis Method (ATAM).ResultsThe main result was that the participants produced their best results when applying QuaDAI, signifying that the participants obtained architectures with better values for the NFRs faster, and that they found the method easier to use, more useful and more likely to be used. The results of the meta-analysis carried out to aggregate the results obtained in the individual experiments also confirmed these results.ConclusionsThe results support the hypothesis that QuaDAI would achieve better results than ATAM in the experiments and that QuaDAI can be considered as a promising approach with which to perform architectural evaluations that occur after the product architecture derivation in model-driven SPL development processes when carried out by novice software evaluators.     

The Pro-PD Process Model for Product Derivation within software product lines

BackgroundThe derivation of products from a software product line is a time consuming and expensive activity. Despite recognition that an effective process could alleviate many of the difficulties associated with product derivation, existing approaches have different scope, emphasise different aspects of the derivation process and are frequently too specialised to serve as a general solution.ObjectiveTo define a systematic process that will provide a structured approach to the derivation of products from a software product line, based on a set of tasks, roles and artefacts.MethodThrough a series of research stages using sources in industry and academia, this research has developed a Process Model for Product Derivation (Pro-PD). We document the evidence for the construction of Pro-PD and the design decisions taken. We evaluate Pro-PD through comparison with prominent existing approaches and standards.ResultsThis research presents a Process Model for Product Derivation (Pro-PD). Pro-PD describes the tasks, roles and work artefacts used to derive products from a software product line.ConclusionIn response to a need for methodological support, we developed Pro-PD (Process Model for Product Derivation). Pro-PD was iteratively developed and evaluated through four research stages. Our research is a first step toward an evidence-based methodology for product derivation and a starting point for the definition of a product derivation approach.     

Applying a selection method to choose Quality Attribute Techniques

ContextSoftware products have requirements on software quality attributes such as safety and performance. Development teams use various specific techniques to achieve these quality requirements. We call these “Quality Attribute Techniques” (QATs). QATs are used to identify, analyse and control potential product quality problems. Although QATs are widely used in practice, there is no systematic approach to represent, select, and integrate them in existing approaches to software process modelling and tailoring.ObjectiveThis research aims to provide a systematic approach to better select and integrate QATs into tailored software process models for projects that develop products with specific product quality requirements.MethodA selection method is developed to support the choice of appropriate techniques for any quality attribute, across the lifecycle. The selection method is based on three perspectives: (1) risk management; (2) process integration; and (3) cost/benefit using Analytic Hierarchy Process (AHP). An industry case study is used to validate the feasibility and effectiveness of applying the selection method.ResultsThe case study demonstrates that the selection method provides a more methodological and effective approach to choose QATs for projects that target a specific quality attribute, compared to the ad hoc selection performed by development teams.ConclusionThe proposed selection method can be used to systematically choose QATs for projects to target specific product qualities throughout the software development lifecycle.     

SimPL: A product-line modeling methodology for families of integrated control systems

ContextIntegrated control systems (ICSs) are heterogeneous systems where software and hardware components are integrated to control and monitor physical devices and processes. A family of ICSs share the same software code base, which is configured differently for each product to form a unique installation. Due to the complexity of ICSs and inadequate automation support, product configuration in this context is typically error-prone and costly.ObjectiveAs a first step to overcome these challenges, we propose a UML-based product-line modeling methodology that provides a foundation for semi-automated product configuration in the specific context of ICSs.MethodWe performed a comprehensive domain analysis to identify characteristics of ICS families, and their configuration challenges. Based on this, we formulated the characteristics of an adequate configuration solution, and derived from them a set of modeling requirements for a model-based solution to configuration. The SimPL methodology is proposed to fulfill these requirements.ResultsTo evaluate the ability of SimPL to fulfill the modeling requirements, we applied it to a large-scale industrial case study. Our experience with the case study shows that SimPL is adequate to provide a model of the product family that meets the modeling requirements. Further evaluation is still required to assess the applicability and scalability of SimPL in practice. Doing this requires conducting field studies with human subjects and is left for future work.ConclusionWe conclude that configuration in ICSs requires better automation support, and UML-based approaches to product family modeling can be tailored to provide the required foundation.     

Improving software product line configuration: A quality attribute-driven approach

ContextDuring the definition of software product lines (SPLs) it is necessary to choose the components that appropriately fulfil a product’s intended functionalities, including its quality requirements (i.e., security, performance, scalability). The selection of the appropriate set of assets from many possible combinations is usually done manually, turning this process into a complex, time-consuming, and error-prone task.ObjectiveOur main objective is to determine whether, with the use of modeling tools, we can simplify and automate the definition process of a SPL, improving the selection process of reusable assets.MethodWe developed a model-driven strategy based on the identification of critical points (sensitivity points) inside the SPL architecture. This strategy automatically selects the components that appropriately match the product’s functional and quality requirements. We validated our approach experimenting with different real configuration and derivation scenarios in a mobile healthcare SPL where we have worked during the last three years.ResultsThrough our SPL experiment, we established that our approach improved in nearly 98% the selection of reusable assets when compared with the unassisted analysis selection. However, using our approach there is an increment in the time required for the configuration corresponding to the learning curve of the proposed tools.ConclusionWe can conclude that our domain-specific modeling approach significantly improves the software architect’s decision making when selecting the most suitable combinations of reusable components in the context of a SPL.     

Key activities for product derivation in software product lines

More and more organizations adopt software product lines to leverage extensive reuse and deliver a multitude of benefits such as increased quality and productivity and a decrease in cost and time-to-market of their software development. When compared to the vast amount of research on developing product lines, relatively little work has been dedicated to the actual use of product lines to derive individual products, i.e., the process of product derivation. Existing approaches to product derivation have been developed independently for different aims and purposes. While the definition of a general approach applicable to every domain may not be possible, it would be interesting for researchers and practitioners to know which activities are common in existing approaches, i.e., what are the key activities in product derivation. In this paper we report on how we compared two product derivation approaches developed by the authors in two different, independent research projects. Both approaches independently sought to identify product derivation activities, one through a process reference model and the other through a tool-supported derivation approach. Both approaches have been developed and validated in research industry collaborations with different companies. Through the comparison of the approaches we identify key product derivation activities. We illustrate the activities’ importance with examples from industry collaborations. To further validate the activities, we analyze three existing product derivation approaches for their support for these activities. The validation provides evidence that the identified activities are relevant to product derivation and we thus conclude that they should be considered (e.g., as a checklist) when developing or evaluating a product derivation approach.     

Advanced product planning: a comprehensive process for systemic definition of new product requirements

This paper reports results of research into the definition of requirements for new consumer products––specifically, electro-mechanical products. The research dealt with the derivation of design requirements that are demonstrably aligned with stakeholder needs. The paper describes a comprehensive process that can enable product development teams to deal with statements of product requirements, as originally collected through market research activities, in a systematic and traceable manner from the early, fuzzy front end, stages of the design process. The process described has been based on principles of systems engineering. A case study from its application and evaluation drawn from the power sector is described in this paper. The case study demonstrates how the process can significantly improve product quality planning practices through revision of captured product requirements, analysis of stakeholder requirements and derivation of design requirements. The paper discusses benefits and issues from the use of the process by product development teams, and identifies areas for further research. Finally, the conclusions drawn from the reported research are presented.

Requirements monitoring frameworks: A systematic review

ContextSoftware systems today often interoperate with each other, thus forming a system of systems (SoS). Due to the scale, complexity, and heterogeneity of SoS, determining compliance with their requirements is challenging, despite the range of existing monitoring approaches. The fragmented research landscape and the diversity of existing approaches, however, make it hard to understand and analyze existing research regarding its suitability for SoS.ObjectiveThe aims of this paper are thus to systematically identify, describe, and classify existing approaches for requirements-based monitoring of software systems at runtime. Specifically, we (i) analyze the characteristics and application areas of monitoring approaches proposed in different domains, we (ii) systematically identify frameworks supporting requirements monitoring, and finally (iii) analyze their support for requirements monitoring in SoS.MethodWe performed a systematic literature review (SLR) to identify existing monitoring approaches and to classify their key characteristics and application areas. Based on this analysis we selected requirements monitoring frameworks, following a definition by Robinson, and analyzed them regarding their support for requirements monitoring in SoS.ResultsWe identified 330 publications, which we used to produce a comprehensive overview of the landscape of requirements monitoring approaches. We analyzed these publications regarding their support for Robinson’s requirements monitoring layers, resulting in 37 identified frameworks. We investigated how well these frameworks support requirements monitoring in SoS.ConclusionsWe conclude that most existing approaches are restricted to certain kinds of checks, particular types of events and data, and mostly also limited to one particular architectural style and technology. This lack of flexibility makes their application in an SoS context difficult. Also, systematic and automated variability management is still missing. Regarding their evaluation, many existing frameworks focus on measuring the performance overhead, while only few frameworks have been assessed in cases studies with real-world systems.     

The DOPLER meta-tool for decision-oriented variability modeling: a multiple case study

The variability of a product line is typically defined in models. However, many existing variability modeling approaches are rigid and don’t allow sufficient domain-specific adaptations. We have thus been developing a flexible and extensible approach for defining product line variability models. Its main purposes are to guide stakeholders through product derivation and to automatically generate product configurations. Our approach is supported by the DOPLER (Decision-Oriented Product Line Engineering for effective Reuse) meta-tool that allows modelers to specify the types of reusable assets, their attributes, and dependencies for their specific system and context. The aim of this paper is to investigate the suitability of our approach for different domains. More specifically, we explored two research questions regarding the implementation of variability and the utility of DOPLER for variability modeling in different domains. We conducted a multiple case study consisting of four cases in the domains of industrial automation systems and business software. In each of these case studies we analyzed variability implementation techniques. Experts from our industry partners then developed domain-specific meta-models, tool extensions, and variability models for their product lines using DOPLER. The four cases demonstrate the flexibility of the DOPLER approach and the extensibility and adaptability of the supporting meta tool.     

Requirements engineering for software product lines: A systematic literature review

ContextSoftware product line engineering (SPLE) is a growing area showing promising results in research and practice. In order to foster its further development and acceptance in industry, it is necessary to assess the quality of the research so that proper evidence for adoption and validity are ensured. This holds in particular for requirements engineering (RE) within SPLE, where a growing number of approaches have been proposed.ObjectiveThis paper focuses on RE within SPLE and has the following goals: assess research quality, synthesize evidence to suggest important implications for practice, and identify research trends, open problems, and areas for improvement.MethodA systematic literature review was conducted with three research questions and assessed 49 studies, dated from 1990 to 2009.ResultsThe evidence for adoption of the methods is not mature, given the primary focus on toy examples. The proposed approaches still have serious limitations in terms of rigor, credibility, and validity of their findings. Additionally, most approaches still lack tool support addressing the heterogeneity and mostly textual nature of requirements formats as well as address only the proactive SPLE adoption strategy.ConclusionsFurther empirical studies should be performed with sufficient rigor to enhance the body of evidence in RE within SPLE. In this context, there is a clear need for conducting studies comparing alternative methods. In order to address scalability and popularization of the approaches, future research should be invested in tool support and in addressing combined SPLE adoption strategies.     

An empirical study on the implementation and evaluation of a goal-driven software development risk management model

ContextBuilding a quality software product in the shortest possible time to satisfy the global market demand gives an enterprise a competitive advantage. However, uncertainties and risks exist at every stage of a software development project. These can have an extremely high influence on the success of the final software product. Early risk management practice is effective to manage such risks and contributes effectively towards the project success.ObjectiveDespite risk management approaches, a detailed guideline that explains where to integrate risk management activities into the project is still missing. Little effort has been directed towards the evaluation of the overall impact of a risk management method. We present a Goal-driven Software Development Risk Management Model (GSRM) and its explicit integration into the requirements engineering phase and an empirical investigation result of applying GSRM into a project.MethodWe combine the case study method with action research so that the results from the case study directly contribute to manage the studied project risks and to identify ways to improve the proposed methodology. The data is collected from multiple sources and analysed both in a qualitative and quantitative way.ResultsWhen risk factors are beyond the control of the project manager and project environment, it is difficult to control these risks. The project scope affects all the dimensions of risk. GSRM is a reasonable risk management method that can be employed in an industrial context. The study results have been compared against other study results in order to generalise findings and identify contextual factors.ConclusionA formal early stage risk management practice provides early warning related to the problems that exists in a project, and it contributes to the overall project success. It is not necessary to always consider budget and schedule constraints as top priority. There exist issues such as requirements, change management, and user satisfaction which can influence these constraints.     

Facilitating construction of safety cases from formal models in Event-B

ContextCertification of safety–critical software systems requires submission of safety assurance documents, e.g., in the form of safety cases. A safety case is a justification argument used to show that a system is safe for a particular application in a particular environment. Different argumentation strategies (informal and formal) are applied to determine the evidence for a safety case. For critical software systems, application of formal methods is often highly recommended for their safety assurance.ObjectiveThe objective of this paper is to propose a methodology that combines two activities: formalisation of system safety requirements of critical software systems for their further verification as well as derivation of structured safety cases from the associated formal specifications.MethodWe propose a classification of system safety requirements in order to facilitate the mapping of informally defined requirements into a formal model. Moreover, we propose a set of argument patterns that aim at enabling the construction of (a part of) a safety case from a formal model in Event-B.ResultsThe results reveal that the proposed classification-based mapping of safety requirements into formal models facilitates requirements traceability. Moreover, the provided detailed guidelines on construction of safety cases aim to simplify the task of the argument pattern instantiation for different classes of system safety requirements. The proposed methodology is illustrated by numerous case studies.ConclusionFirstly, the proposed methodology allows us to map the given system safety requirements into elements of the formal model to be constructed, which is then used for verification of these requirements. Secondly, it guides the construction of a safety case, aiming to demonstrate that the safety requirements are indeed met. Consequently, the argumentation used in such a constructed safety case allows us to support it with formal proofs and model checking results used as the safety evidence.     

Combining service-orientation and software product line engineering: A systematic mapping study

ContextService-Orientation (SO) is a rapidly emerging paradigm for the design and development of adaptive and dynamic software systems. Software Product Line Engineering (SPLE) has also gained attention as a promising and successful software reuse development paradigm over the last decade and proven to provide effective solutions to deal with managing the growing complexity of software systems.ObjectiveThis study aims at characterizing and identifying the existing research on employing and leveraging SO and SPLE.MethodWe conducted a systematic mapping study to identify and analyze related literature. We identified 81 primary studies, dated from 2000–2011 and classified them with respect to research focus, types of research and contribution.ResultThe mapping synthesizes the available evidence about combining the synergy points and integration of SO and SPLE. The analysis shows that the majority of studies focus on service variability modeling and adaptive systems by employing SPLE principles and approaches.In particular, SPLE approaches, especially feature-oriented approaches for variability modeling, have been applied to the design and development of service-oriented systems. While SO is employed in software product line contexts for the realization of product lines to reconcile the flexibility, scalability and dynamism in product derivations thereby creating dynamic software product lines.ConclusionOur study summarizes and characterizes the SO and SPLE topics researchers have investigated over the past decade and identifies promising research directions as due to the synergy generated by integrating methods and techniques from these two areas.     

A HCI technique for improving requirements elicitation

ContextTo develop usable software we need to understand the users that will interact with the system. Personas is a HCI technique that gathers information about users in order to comprehend their characteristics. This information is used to define fictitious persons on which development should focus. Personas provides an understanding of the user, often overlooked in SE developments.ObjectiveThe goal of our research is to modify Personas to readily build the technique into the requirements stage of regular SE developments.MethodWe tried to apply Cooper’s version of the Personas technique and we found shortcomings in both the definition of the procedure to be enacted and the formalization of the product resulting from the execution of each step of the Personas technique. For each of these limitations (up to a total of 11), we devised an improvement to be built into Personas. We have incorporated these improvements into a SE version of Personas. The improved Personas avoid the weaknesses encountered by an average software developer unfamiliar with HCI techniques applying the original Personas.ResultsWe aim to improve requirements elicitation through the use of Personas. We have systematized and formalized Personas in the SE tradition in order to build this new version of the technique into the requirements stage. We have applied our proposal in an application example.ConclusionThe integration of Personas into the SE requirements stage might improves the understanding of what the software product should do and how it should behave. We have modified the HCI Personas technique to comply with the levels of systematization required by SE. We have enriched the SE requirements process by incorporating Personas activities into requirements activities. Requirements elicitation and requirements analysis are the RE activities most affected by incorporating Personas.     

A systematic review on strategic release planning models

ContextStrategic release planning (sometimes referred to as road-mapping) is an important phase of the requirements engineering process performed at product level. It is concerned with selection and assignment of requirements in sequences of releases such that important technical and resource constraints are fulfilled.ObjectivesIn this study we investigate which strategic release planning models have been proposed, their degree of empirical validation, their factors for requirements selection, and whether they are intended for a bespoke or market-driven requirements engineering context.MethodsIn this systematic review a number of article sources are used, including Compendex, Inspec, IEEE Xplore, ACM Digital Library, and Springer Link. Studies are selected after reading titles and abstracts to decide whether the articles are peer reviewed, and relevant to the subject.ResultsTwenty four strategic release planning models are found and mapped in relation to each other, and a taxonomy of requirements selection factors is constructed.ConclusionsWe conclude that many models are related to each other and use similar techniques to address the release planning problem. We also conclude that several requirement selection factors are covered in the different models, but that many methods fail to address factors such as stakeholder value or internal value. Moreover, we conclude that there is a need for further empirical validation of the models in full scale industry trials.     

Shared service recommendations from requirement specifications: A hybrid syntactic and semantic toolkit

ContextSoftware Requirement Specifications (SRSs) are central to software lifecycles. An SRS defines the functionalities and constraints of a desired software system, hence it often serves as reference for further development. Software lifecycles concerned with the conversion of traditional systems into more service-oriented infrastructures can benefit from understanding potential shared capabilities through the analysis of SRSs.ObjectiveIn this paper, we propose an automated approach capable of recommending shared software services from multiple text-based SRSs created by different organizations. Our goal is to facilitate the identification of overlapping requirements in these specifications and subsequently recommend shared components, which promotes software reuse. The shared components can be implemented as services that are invoked across different systems.MethodOur approach leverages the syntactic similarity of the SRS text augmented with semantic information derived from the WordNet database. This work extends our earlier studies by introducing an algorithm that utilizes noun, verb, and predicate relations to enhance the discovery of equivalent requirements and the recommendation of reusable services. A prototype system is implemented to evaluate the approach and experimental results have shown effective recommendation of requirements and their realized shared services.ResultsOur automatic recommendation approach generates recommendations in few minutes compared to 9 h when services are manually inspected by developers. Our approach is also able to recommend services that are overlooked by the same developers, and to identify similarity between requirements even if these requirements are reworded.ConclusionWe show through experimentation that we can efficiently recommend services by leveraging both the syntactical structure and the semantic information of a requirements document and that our approach is more effective than the manual selection of services by experts. We also show that our approach is effective in detecting similar requirements for a single system and hence discovering opportunities for software reuse.     

Managing requirements inter-dependency for software product line derivation

Software Product Line Engineering (SPLE) can reduce software development costs, reduce time to market and improve product quality. A software product line is a set of software products sharing a set of common features but containing variation points. Successful SPLE requires making selection decisions at variation points effectively and efficiently. A significant challenge is how to identify, represent and manage the inter-dependency of selection decisions for requirements. We developed the concept of a meta-model for requirement decision models to bring formalism and consistency to the structure and to model inter-dependencies between requirement selection decisions. Here we present a meta-model for requirement selection decisions that includes inter-dependencies and we use a mobile phone worked example to illustrate our approach. To support our method, we developed two separate tools, V-Define (for domain decision model construction) and V-Resolve (for new product derivation). Finally the results of a metal processing product line case study using the tools are described.

A theory of distances in software engineering

ContextCoordinating a software project across distances is challenging. Even without geographical and time zone distances, other distances within a project can cause communication gaps. For example, organisational and cognitive distances between product owners and development-near roles such as developers and testers can lead to differences in understanding and interpretation of the business requirements. Applying good software development practices, known to enhance alignment and coordination within development projects, can alleviate these challenges.ObjectiveThe aim of our research is to identify and describe underlying factors which can explain why certain practices support aligning and coordinating software development projects.MethodWe have inductively generated a theory analysing empirical data consisting of 15 interviews from 5 different companies. The systematic and iterative analysis was based on an initial hypothesis that distances affect development, and on results from previous research.ResultsWe present a theory of distances that explains how practices improve the communication within a project by impacting distances between people, activities and artefacts. We also present a theoretical model of how specific alignment practices affect different types of distances.ConclusionsThe results provide a basis for further research and can be used by software organisations to improve on software practice.     

Systematizing requirements elicitation technique selection

ContextThis research deals with requirements elicitation technique selection for software product requirements and the overselection of open interviews.ObjectivesThis paper proposes and validates a framework to help requirements engineers select the most adequate elicitation techniques at any time.MethodWe have explored both the existing underlying theory and the results of empirical research to build the framework. Based on this, we have deduced and put together justified proposals about the framework components. We have also had to add information not found in theoretical or empirical sources. In these cases, we drew on our own experience and expertise.ResultsA new validated approach for requirements technique selection. This new approach selects techniques other than open interview, offers a wider range of possible techniques and captures more requirements information.ConclusionsThe framework is easily extensible and changeable. Whenever any theoretical or empirical evidence for an attribute, technique or adequacy value is unearthed, the information can be easily added to the framework.