Open-source software product line extraction processes: the ArgoUML-SPL and Phaser cases

Software Product Lines (SPLs) are rarely developed from scratch. Commonly, they emerge from one product when there is a need to create tailored variants, or from existing variants created in an ad-hoc way once their separated maintenance and evolution become challenging. Despite the vast literature about re-engineering systems into SPLs and related technical approaches, there is a lack of detailed analysis of the process itself and the effort involved. In this paper, we provide and analyze empirical data of the extraction processes of two open source case studies, namely ArgoUML and Phaser. Both cases emerged from the transition of a monolithic system into an SPL. The analysis relies on information mined from the version control history of their respective source-code repositories and the discussion with developers that took part in the process. Unlike previous works that focused mostly on the structural results of the final SPL, the contribution of this study is an in-depth characterization of the processes. With this work, we aimed at providing a deeper understanding of the strategies for SPL extraction and their implications. Our results indicate that the source code changes can range from almost a fourth to over half of the total lines of code. Developers may or may not use branching strategies for feature extraction. Additionally, the problems faced during the extraction process may be due to lack of tool support, complexity on managing feature dependencies and issues with feature constraints. We made publicly available the datasets and the analysis scripts of both case studies to be used as a baseline for extractive SPL adoption research and practice.This research was partially funded by CNPq, grant no. 408356/2018-9; FAPPR, grant no. 51435; and FAPERJ PDR-10 Fellowship 202073/2020. Open access funding provided by Johannes Kepler University Lin

Feature-to-Code Traceability in Legacy Software Variants

International audienceExisting similar software variants, developed by ad-hoc reuse technique such as left clone-and-own right, represent a starting point to build a software product line (SPL) core assets. To re-engineer such legacy software variants into an SPL for systematic reuse, it is important to be able to identify a mapping between features and their implementing source code elements in different variants. Information Retrieval (IR) methods have been used widely to support this mapping in a single software product. This paper proposes a new approach to improve the performance of IR methods when they are applied to a collection of software variants. The novelty of our approach is twofold. On the one hand, it exploits what software variants have in common and how they differ to improve the accuracy of IR results. On the other hand, it reduces the abstraction gap between features and source code by introducing an intermediate level called left code-topic right, for increasing the number of retrieved links that are relevant. We have applied our approach to a collection of seven variants of a large-scale system by using the ArgoUML-SPL modeling tool. The experimental results showed that our approach outperforms conventional application of IR methods as well as the most recent and relevant work on the subject

ModelVars2SPL : an automated approach to reengineer model variants into software product lines

Orientadora : Profª. Drª. Silvia R. VergilioCoorientador : Prof Dr. Roberto E. Lopez-HerrejonTese (doutorado) - Universidade Federal do Paraná, Setor de Ciências Exatas, Programa de Pós-Graduação em Informática. Defesa: Curitiba, 11/04/2017Inclui referências : f. 74-82Área de concentração : Ciência da computaçãoResumo: Linhas de Produto de Software (LPSs) são famílias de sistemas de software relacionados que são desenvolvidos para um segmento de mercado ou domínio. Comumente, LPSs surgem de um conjunto de variantes existentes, quando a manutenção e/ou evolução individuais tornam-se complexas. Contudo, as abordagens encontradas na literatura para extração de LPS a partir de variantes existentes não dão suporte a modelos de projeto, são parcialmente automatizadas, ou não refletem restrições de domínio em termos de combinação de características. Para lidar com estas limitações, o objetivo deste trabalho é apresentar uma abordagem automatizada para fazer a reengenharia de variantes de modelos em uma LPS, chamada ModelVars2SPL (Variantes de Modelos para Linha de Produto de Software, do Inglês Model Variants to Software Product Line). A entrada para a abordagem é um conjunto de diagramas de classe Linguagem de Modelagem Unificada (UML) e uma lista de características que estes implementam. Todo o processo de reengenharia é coberto, e a saída inclui (i) um Modelo de Características, que representa a combinação de características das variantes de entrada, e (ii) uma Arquitetura de Linha de Produto, que representa uma arquitetura global com características anotadas. O processo de reengenharia da ModelVars2SPL é composto por quatro passos, sendo dois deles apoiados em técnicas baseadas em busca, e os dois outros baseados em algoritmos determinísticos. Não existe a necessidade de especialistas humanos para obter soluções. Para avaliar a abordagem proposta, foi conduzido um experimento para aferir a qualidade das soluções obtidas. A qualidade dos Modelos de Características e das Arquiteturas de Linha de Produto foi medida considerando-se o quão bem as variantes de entrada foram representadas. Além disso, a qualidade das saídas em cada passo da abordagem foi avaliada levando-se em consideração os objetivos do processo de reengenharia. Para a experimentação utilizaram-se dez estudos de caso representando dois cenários diferentes. Os resultados da avaliação mostram que a abordagem consegue obter soluções com alto grau de corretude em termos de representação das variantes de entrada, e que as saídas dos passos estão de acordo com as fases do processo de reengenharia. Com base em um exemplo de uso de uma solução mostra-se como os artefatos de LPS obtidos facilitam a atividade de manutenção. Palavras-chave: Reúso, Reengenharia, Linha de Produto de Software, Extração de LPS, Engenharia de Software Baseada em Busca.Abstract: Software Product Lines (SPLs) are families of related software systems developed for specific market segments or domains. SPLs commonly emerge from sets of existing variants when their individual maintenance and/or evolution become complex. However, current approaches for SPL extraction from existing variants do not support design models, are partially automated, or do not reflect domain constraints in terms of feature combinations. To tackle these limitations, the goal of this work is to present an automated approach to reengineer model variants into an SPL, called ModelVars2SPL (Model Variants to Software Product Line). The input of the approach is a set of Unified Modeling Language (UML) class diagrams and the list of features they implement. All the reengineering process is covered, and the output includes (i) a Feature Model, which represents the combinations of features of the input variants, and (ii) a Product Line Architecture, which represents a global architecture with feature-related annotations. The reengineering process of ModelVars2SPL is composed of four steps, two of them rely on searchbased techniques and the others are based on deterministic algorithms. There is no need for human experts for obtaining solutions. We conducted an experiment to evaluate the quality of the solutions obtained with the proposed approach. The quality of the FMs and PLAs was measured by considering how well these artifacts represent the input variants. Furthermore, we evaluate the quality of the outputs in each step of the approach taking into account the goals of the reengineering process. For the experimentation we used ten case studies representing two di_erent scenarios. The results of the evaluation show that the approach can obtain solutions with high degree of correctness in terms of representing the input variants, and that the outputs of the steps are in accordance to the phases of the reengineering process. Based on an example of use we show how the obtained FM and PLA make easier the maintenance activity. Keywords: Reuse, Reengineering, Software Product Line, SPL extraction, Search-Based Software Engineering