Evolving an industrial analytics product line architecture

The software product line (PL) architecture (PLA) is one of the most important PL core assets as it is the abstraction of the products that can be generated, and it represents similarities and variabilities of a PL. Its quality attributes analysis and evaluation can serve as a basis for analyzing the managerial and economical values of a PL. We proposed metrics for PLA complexity and extensibility quality attributes. This paper is concerned with the empirical validation of such metrics. As a result of the experimental work we can conclude that the metrics are relevant indicators of complexity and extensibility of PLA by presenting their correlation analysis.

A software product line (SPL) usually involves a shared set of core assets and a series of application products. To ensure consistency, the evolution of the core assets and all the application products should be coordinated and synchronized under a unified evolution process. Therefore, SPL evolution often involves cross-product propagation and synchronization besides application derivation based on core assets, presenting quite different characteristic from the evolution of individual software products. As software architectures, including the product line architecture (PLA) and application architectures, play a central role in SPL engineering and evolution, architecture-based evolution analysis is a natural way for analyzing and managing SPL evolution. In this paper, we explore common practices of architecture evolution and the rationale behind in industrial SPL development. To this end, we conduct a case study with Wingsoft examination system product line (WES-PL), an industrial product line with an evolution history of eight years and more than 10 application products. In the case study, we reviewed the evolution history of WES-PL architecture and analyzed several typical evolution cases. Based on the historical analysis, we identify some special problems in industrial SPL practice from the aspect of architecture evolution and summarize some useful experiences about SPL evolution decisions to complement classical SPL methodology. On the other hand, we also propose some possible improvements for the evolution management in WES-PL.

In the software product line research, product variants typically differ by their functionality and quality attributes are not purposefully varied. The goal is to study purposeful performance variability in software product lines, in particular, the motivation to vary performance, and the strategy for realizing performance variability in the product line architecture. The research method was a theory-building case study that was augmented with a systematic literature review. The case was a mobile network base station product line with capacity variability. The data collection, analysis and theorizing were conducted in several stages: the initial case study results were augmented with accounts from the literature. We constructed three theoretical models to explain and characterize performance variability in software product lines: the models aim to be generalizable beyond the single case. The results describe capacity variability in a base station product line. Thereafter, theoretical models of performance variability in software product lines in general are proposed. Performance variability is motivated by customer needs and characteristics, by trade-offs and by varying operating environment constraints. Performance variability can be realized by hardware or software means; moreover, the software can either realize performance differences in an emergent way through impacts from other variability or by utilizing purposeful varying design tactics. The results point out two differences compared with the prevailing literature. Firstly, when the customer needs and characteristics enable price differentiation, performance may be varied even with no trade-offs or production cost differences involved. Secondly, due to the dominance of feature modeling, the literature focuses on the impact management realization. However, performance variability can be realized through purposeful design tactics to downgrade the available software resources and by having more efficient hardware.

Software architecture has been a key research area in the software engineering community due to its significant role in creating high-quality software. The trend of developing product lines rather than single products has made the software product line a viable option in the industry. Software product line architecture (SPLA) is regarded as one of the crucial components in the product lines, since all of the resulting products share this common architecture. The increased popularity of software product lines demands a process maturity evaluation methodology. Consequently, this paper presents an architecture process maturity model for software product line engineering to evaluate the current maturity of the product line architecture development process in an organization. Assessment questionnaires and a rating methodology comprise the framework of this model. The objective of the questionnaires is to collect information about the SPLA development process. Thus, in general this work contributes towards the establishment of a comprehensive and unified strategy for the process maturity evaluation of software product line engineering. Furthermore, we conducted two case studies and reported the assessment results, which show the maturity of the architecture development process in two organizations.

This report explains the challenges experienced as Overwatch Textron Systems transitioned to a software product line approach. Overwatch Textron Systems provides both software products and custom software development in the domain of intelligence planning, collection and analysis to the U.S. Government and its allies. This report: a) Describes the approach taken to transition Overwatch Textron Systems to a product line organization. b) Provides an overview of the Overwatch Textron Systems software product line; the Overwatch Intelligence Center. c) Describes the product line architecture that is key to the Overwatch Intelligence Center software product line. d) Provides a summary of the lessons learned during the transition.

The Product Line Architecture (PLA) can be improved by taking into account key factors such as feature modularization, and by continuously evaluating its design according to metrics. Search-Based Software Engineering (SBSE) principles can be used to support an informed-design of PLAs. However, existing search-based design works address only traditional software design not considering intrinsic Software Product Line aspects. This paper presents MOA4PLA, a search-based approach to support the PLA design. It gives a multi-objective treatment to the design problem based on specific PLA metrics. A metamodel to represent the PLA and a novel search operator to improve feature modularization are proposed. Results point out that the application of MOA4PLA leads to PLA designs with well modularized features, contributing to improve features reusability and extensibility. It raises a set of solutions with different design trade-offs that can be used to improve the PLA design.

Microservice has been successfully employed in software industry [1, 11], as they provide modularization and easy management of small and autonomous services, high availability, scalability and short time-to-market. A recent study on microservices shows that most studies generate specific solutions, which emphasize the need for fundamental research, proposals of reusable practices and works that focus on providing information to ease communication between architects and stakeholders [11] -- software architecture can be a powerful tool for this regard. The definition and documentation of the software product line architecture (PLA) is an important activity, especially for inception and extraction of microservice-oriented PLA, because they involve decisions about how to design customizable microservices, how to arrange the communication between microsservices and APIs, etc. In this work, it is proposed a metamodel for the specification of microsserve-oriented PLA design in order to assist the developer in carrying out such an activity. The proposed metamodel was validated in an exploratory study, in which a new PLA was designed through the instantiation of the proposed metamodel and a product was configured from the designed PLA. Both the metamodel and its instantiation were evaluated in a survey involving software developers. The results indicate that the metamodel addresses the structural needs of microservice-oriented architectures. The main contributions of this work are (i) to assist the software product line developers in the specification and documentation of microservice-oriented PLA design and (ii) the lessons about the industrial practice learned from the surveys that are useful to enhance the proposed metamodel.

Software product family or line is a software engineering paradigm that systematizes reuse. In software product line engineering, two phases are distinguished: domain engineering which is in charge of developing a common infrastructure and assets and application engineering which makes use of those assets to generate the products. One of the key aspects of product lines is variability and its management. However, the main focus has been on functional variability and quality variability in software product lines has not received so much attention by researchers. In a product line different members of the line may require different levels of a quality requirement, for instance they could differ in terms of their availability, security, reliability, etc. Due to this variability, quality evaluation in software product lines is much more complicated that in single-systems. One alternative is to evaluate all the products of a line but it is very expensive and ways of reducing evaluation efforts are necessary. In this direction, the paper presents a method for facilitating cost-effective quality evaluation of a product line taking into consideration variability on quality attributes.

Intelligent tutoring systems (ITSs) are effective to provide instruction for students in several situations. Many works have been using gamification by adding game elements to learning contexts aiming to engage students and to drive desired learning behaviours. However, the design of gamified ITS should deal with a huge variability. Software product lines (SPLs) promise to offer rapid product development and more affordable development costs to build software from the same family. A key factor to successfully implement a product-line approach is to structure commonalities and variabilities into a product line architecture (PLA). In this paper, we propose a PLA for developing gamified ITSs that uses an ontology-driven feature modelling strategy. We illustrate how our architecture could be applied to instantiate a product on the basic math domain. We also discuss a set of implications of using it as well as how it could support the evolution/changing of gamified ITSs.

Software Product Lines (SPLs) is a reuse approach in which a family of products is generalized in a common architecture that can be adapted to different clients. The Product Line Architecture (PLA) is one of the most important artifacts of a SPL. PLA design requires great human effort as it involves several factors that are usually in conflict. To ease this task, PLA design can be formulated as an optimization problem with many factors, i.e, as a multi-objective optimization problem. In this context, the MOA4PLA approach was proposed to optimize PLA design using search algorithms and metrics specific to the context. This approach supported by OPLA-Tool has already been used in several works demonstrating its applicability. However, MOA4PLA does not take into account aspects that are subjective, such as the preferences of a particular Decision Maker (DM). To do so, this paper presents a proposal to incorporate the user preferences in the optimization process performed by MOA4PLA, through an interactive process in which the DM subjectively evaluates the solutions in processing time. Thus, the solutions generated can be better suited to the DM's needs or preferences. In order to allow the user interaction, modifications were made in MOA4PLA and implemented in the OPLA-Tool. Aiming at an initial validation of the proposal, an exploratory study was carried out, composed of two experiments: a qualitative and a quantitative. These experiments were realized with the participation of a software architect. Empirical results pointed out that the proposed interactive process enables the generation of PLAs that are in accordance with the architect's preferences. Another significant contribution are the lessons learned on how to improve the interactive process.

Product lines are an important system development paradigm in the automotive industry to amortize costs beyond a single product. The paradigm is well established in the mechanical and electrical engineering practise in automotive companies like Bosch. As software is covering more and more functionality in cars, software product lines are getting more attention. The architecture of a software-intensive system is a key asser in developing a software product line.The Architecture Trade-off Analysis Method (ATAM) developed by the SEI assesses the quality of software architecture early in the development process. ATAM is therefore a useful review technique to guarantee important quality attributes of every single product created with the product line architecture later on. This article reports about the experience Bosch made in using ATAM in two cases.Benefits in using ATAM are not only the review results itself but a better documented and better understood architecture. We experienced the most important benefit of ATAM is the rising stakeholder's awareness of architectural decisions, tradeoffs, and risks. It illuminates the software architecture better than any written documentation.Bosch employees are trained in the evaluation roles in order to trasition ATAM to Bosch.The reports conclude with some suggestions fo improving the ATAM itself and the training of ATAM roles.

Software product line (SPL) is a software engineering paradigm for software development. A software product within a product line often has specific functionalities that are not common to all other products within the product line. Those specific functionalities are termed “variant features” in a product line. SPL paradigm involves the modeling of variant features. However, little work in SPL investigates and addresses the modeling of variant features specific to user interface (UI). Unified Modeling Language (UML) is the de facto modeling language for object-oriented software systems. It is known that UML needs better support in modeling UIs. Thus, much research developed UML extensions to improve UML support in modeling UIs. Yet little of this work is related to developing such extensions for modeling UIs for SPLs in which variant features specific to UI modeling must be addressed. This research develops a UML extension -Web User Interface Modeling Language (WUIML) to address these problems. WUIML defines elements for modeling variant features specific to user interfaces for Web-based SPLs. The model elements in WUIML extend from the metaclass and BasicActivity of the UML2.0 metamodel. WUIML integrates the modeling of variant features specific to user interfaces to UML. For example, in a Web-based patient registration software product line, member products targeting British users may use British date format in the user interface, while member products targeting United States users may use United States date format in the user interface. Thus, this is a variant feature for this product line. WUIML defines a model element, XOR, to represent such exclusive or conditions in a product line user interface model. WUIML would reduce SPL engineers’ efforts needed in UI development. To validate the WUIML research outcome, a case study was conducted. The results of this empirical study indicate that modeling UIs for Web-based SPLs using WUIML is more effective and efficient than using standard UML.

A systematic mapping study on software product line evolution: From legacy system reengineering to product line refactoring

As society is evolving in a digital direction, we should be more oriented in developing new solutions to reduce the investment costs for digitalization solutions. Digitalization foresees the integration of stakeholders in ecosystems, e.g., a factory, an airport, and a bridge. Such integration requires data sharing among different local automation systems owned by different legal bodies, which are possibly located in different countries under their legal systems. The sharing of data enables the optimization of productivity, raw material yield, energy and environmental footprint, etc., which is the basic motivation for automation. Scalability is another key characteristic of a future product, services, and production line architecture. It is a significant investment and should fit for volume and premium products.

In automotive system design, system architects increasingly use model-based approaches for defining product line architectures (PLAs). This trend is strongly supported by the emergence of domain standards like EAST-ADL and AUTOSAR that facilitate a system design approach based on systematic reuse. In our work, we focus on the automated exploration of PLA design spaces by means of multi-objective optimization and ask what are challenges that stakeholders face as part of this design task. Optimizing PLA design spaces shares certain challenges with conventional architecture optimization, like conflicting quality goals and potentially vast design spaces. However, PLA optimization exacerbates these challenges by an additional layer of complexity in the system architecture, due to product line variability in the system. Our main focus in this paper is on achieving a better understanding of the stakeholder requirements on a support infrastructure for automated PLA design space exploration based on PLA system models. We also address the challenges that stakeholders must overcome when integrating such an approach into an existing process landscape. For that purpose, we conducted a study with automotive industry experts and analyzed the findings using the qualitative data analysis methods of Grounded Theory. Based on the study results, we derive a set of challenges for the realization and integration of automated and semi-automated PLA design space exploration in industrial environments.