Performance variability in software product lines: proposing theories from a case study

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.     

Variability extraction and modeling for product variants

Fast-changing hardware and software technologies in addition to larger and more specialized customer bases demand software tailored to meet very diverse requirements. Software development approaches that aim at capturing this diversity on a single consolidated platform often require large upfront investments, e.g., time or budget. Alternatively, companies resort to developing one variant of a software product at a time by reusing as much as possible from already-existing product variants. However, identifying and extracting the parts to reuse is an error-prone and inefficient task compounded by the typically large number of product variants. Hence, more disciplined and systematic approaches are needed to cope with the complexity of developing and maintaining sets of product variants. Such approaches require detailed information about the product variants, the features they provide and their relations. In this paper, we present an approach to extract such variability information from product variants. It identifies traces from features and feature interactions to their implementation artifacts, and computes their dependencies. This work can be useful in many scenarios ranging from ad hoc development approaches such as clone-and-own to systematic reuse approaches such as software product lines. We applied our variability extraction approach to six case studies and provide a detailed evaluation. The results show that the extracted variability information is consistent with the variability in our six case study systems given by their variability models and available product variants.     

软件产品线可变性建模技术系统综述

软件产品线是实现大规模的软件复用、保证高质量的新产品开发的最佳实践.软件产品线的关键问题是如何进行可变性管理,并基于可变性管理实现软件核心资产的复用.软件产品线可变性建模是可变性管理的关键技术,实现产品家族成员的共性和可变性的描述.可变性建模涉及软件开发的全生命周期,在领域工程和应用工程中,尤其是在产品构建过程中,起到重要的作用.从众多的建模技术中选择合适的建模技术是十分困难的,在软件产品线领域中开展了可变性建模技术的系统综述,按照系统综述的方法对可变性建模技术进行了系统总结,根据系统综述规则,选取了从1990 年~2011 年发表的论文进行综述.讨论了系统综述的研究成果,从可变性建模方法分类、重要可变性建模技术对比等方面进行深入的探讨,为建模人员和研究人员对可变性建模技术的选择和研究提供支持.最后分析了可变性建模技术的研究趋势,并对可变性建模技术有待深入的研究难点和发展趋势进行了展望.     

Modes in component behavior specification via EBP and their application in product lines

The concept of software product lines (SPL) is a modern approach to software development simplifying construction of related variants of a product thus lowering development costs and shortening time-to-market. In SPL, software components play an important role. In this paper, we show how the original idea of component mode can be captured and further developed in behavior specification via the formalism of extended behavior protocols (EBP). Moreover, we demonstrate how the modes in behavior specification can be used for modeling behavior of an entire product line. The main benefits include (i) the existence of a single behavior specification capturing the behavior of all product variants, and (ii) automatic verification of absence of communication errors among the cooperating components taking the variability into account. These benefits are demonstrated on a part of a non-trivial case study.     

Classifying variability modeling techniques

Variability modeling is important for managing variability in software product families, especially during product derivation. In the past few years, several variability modeling techniques have been developed, each using its own concepts to model the variability provided by a product family. The publications regarding these techniques were written from different viewpoints, use different examples, and rely on a different technical background. This paper sheds light on the similarities and differences between six variability modeling techniques, by exemplifying the techniques with one running example, and classifying them using a framework of key characteristics for variability modeling. It furthermore discusses the relation between differences among those techniques, and the scope, size, and application domain of product families.     

基于特征模型的软件产品线可变性建模方法

特征建模是软件产品线开发中的一项关键活动,对特征可变性和特征依赖的建模是特征模型中最重要的组成部分。阐述了特征模型的元模型,着重讨论了特征可变性建模过程,详细分析了特征可变性、特征之间关系、特征依赖类型的识别方法和使用特征依赖矩阵的表示方法。在此基础上,还通过一个库房监视系统应用软件的产品线可变性建模实例验证了该方法的有效性。     

一种基于UML的软件产品线可变性建模方法

将UML引入到软件产品线开发中,在产品线可变性分析的基础上,提出了一种基于UML的产品线可变性建模方法。该方法不仅支持可选、多选一等可变点类型的描述,还支持软件产品线可变性的约束建模。在此基础上,还通过一个手机应用软件的产品线可变性建模实例验证了该方法的有效性。     

Automatic generation of variants depending on changes of product properties in a flexible manufacturing environment

Competition forces manufacturing systems to be flexible and to increase product variety and process complexity. These tasks depend on the flexible design of a bill of materials (BOM), one of the most important inputs in manufacturing planning and control systems. Product variety forces systems to generate BOMs with regard to product properties through a BOM pattern. A variant bill of materials provides a structure to manage product variability. In this study, an algorithm is designed to build a BOM pattern using computer-aided design and computer-aided manufacturing (CAD/CAM) data, and another algorithm is designed to generate variants with regard to product specifications. Genetic algorithm is used to generate new products to provide high product variability for testing algorithms. After the test, both algorithms are applied to a real industry problem. The BOM pattern is built automatically using CAD/CAM data, and variants are generated with regard to the pattern, and the results are discussed.     

面向软件产品家族的变化性建模方法

用户需求和运行环境的变化增加了软件产品开发、维护和演化的难度.另一方面,如果能对同类软件(比如软件产品家族)的变化性实施有效的控制,则可以极大地促进软件复用,提高软件生产效率和质量.对变化性建模是控制变化性的有效手段,既有助于变化性的识别和规约,又能够提供足够的机制支持变化性的演化.提出了一种面向产品家族的变化性建模方法,以变化性的管理策略为指导,从扩展的用况(use case)模型入手捕获系统行为的变化性,以特征模型来组织功能性需求和质量属性并识别其变化性,两种模型对变化性的建模采用相同的机制.还结合一个实例讨论了产品家族变化性建模的全过程.该研究对产品家族变化性的分析与建模具有一定的参考作用.     

Supporting distributed product configuration by integrating heterogeneous variability modeling approaches

ContextIn industrial settings products are developed by more than one organization. Software vendors and suppliers commonly typically maintain their own product lines, which contribute to a larger (multi) product line or software ecosystem. It is unrealistic to assume that the participating organizations will agree on using a specific variability modeling technique—they will rather use different approaches and tools to manage the variability of their systems.ObjectiveWe aim to support product configuration in software ecosystems based on several variability models with different semantics that have been created using different notations.MethodWe present an integrative approach that provides a unified perspective to users configuring products in multi product line environments, regardless of the different modeling methods and tools used internally. We also present a technical infrastructure and a prototype implementation based on web services.ResultsWe show the feasibility of the approach and its implementation by using it with the three most widespread types of variability modeling approaches in the product line community, i.e., feature-based, OVM-style, and decision-oriented modeling. To demonstrate the feasibility and flexibility of our approach, we present an example derived from industrial experience in enterprise resource planning. We further applied the approach to support the configuration of privacy settings in the Android ecosystem based on multiple variability models. We also evaluated the performance of different model enactment strategies used in our approach.ConclusionsTools and techniques allowing stakeholders to handle variability in a uniform manner can considerably foster the initiation and growth of software ecosystems from the perspective of software reuse and configuration.     

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.     

Optimal platform investment for product family design

Existing models for developing modular product families based on a common platform are either too engineering oriented or too marketing centric. In this paper, we propose an intermediate modeling ground that bridges this gap by simultaneously considering essential concepts from engineering and marketing to construct an alternative model for platform-based product families. In this model, each variant (in the platform-based product family) contributes a percentage to overall market coverage inside a target market segment. The extent to which a specific variant contributes to market coverage is linked to its degree of distinctiveness. On the other hand the cost of development of all variants (that constitute the product family) is also dependent on the degree of commonality between these variants. The objective of the model is to maximize market coverage subject to an available development budget. Based on a conceptual design of the product family, the proposed model suggests the optimal initial investment in the platform, the commonality level between variants, and the number of variants to be produced in order to maximize market coverage using both analytical and simulation techniques. An application example using an ice scraper product family is included to demonstrate the proposed model.     

Weaving variability into domain metamodels

Domain-specific modeling languages (DSMLs) are the essence of MDE. A DSML describes the concepts of a particular domain in a metamodel, as well as their relationships. Using a DSML, it is possible to describe a wide range of different models that often share a common base and vary on some parts. On the one hand, some current approaches tend to distinguish the variability language from the DSMLs themselves, implying greater learning curve for DSMLs stakeholders and a significant overhead in product line engineering. On the other hand, approaches integrating variability in DSMLs lack generality and tool support. We argue that aspect-oriented modeling techniques enabling flexible metamodel composition and results obtained by the software product line community to manage and resolve variability form the pillars for a solution for integrating variability into DSMLs. In this article, we consider variability as an independent and generic aspect to be woven into the DSML. In particular, we detail how variability is woven and how to perform product line derivation. We validate our approach through the weaving of variability into two different metamodels: Ecore??widely used for DSML definition??and SmartAdapters, our aspect model weaver. These results emphasize how new abilities of the language can be provided by this means.     

On the refinement of use case models with variability support

Modeling software product lines shall imply modeling from different perspectives with different modeling artifacts such as use case diagrams, component diagrams, class diagrams, activity diagrams, sequence diagrams and others. In this paper, we elaborate on use cases for modeling product lines and we explore them from the perspective of variability by working with the unified modeling language (UML) ?extend? relationship. We also explore them from the perspective of detail by (functionally) refining use cases with ?extend? relationships between them. This paper’s intent is to provide for comprehension about use case modeling with functional refinement when variability is present.     

管理导向的软件产品族变化性建模方法研究

控制和管理软件产品族变化性对提高软件复用性、满足用户多变需求具有重要意义.提出一种管理导向的软件产品族变化性建模(Management-oriented variability modeling,MOVM)方法,该方法以变化性管理为指导,贯穿于整个软件产品族变化性生命周期以及反馈演化过程,对各阶段设计相应的策略以支持变...     

业务流程模型中生成特征模型方法的研究

目前的软件产品系统中,由于现有的造型系统研究的只是单一系统的开发,因此使用现有的方法进行特征造型时就会导致最终开发出来的产品的质量和产量比较低。通过使用增加产品复用性的软件产品线,提出了从业务流程模型中生成特征模型的方法。该方法通过使用重叠操作算法,将业务流程中相似的功能编成一个用例组,清晰地显示了业务流程中的共性和差异性,从而为整个业务流程实现了软件化,提高了产品的质量和产量。     

面向软件密集型系统的体系结构可变性建模

软件体系结构提供了软件系统的高层抽象,对于软件密集型系统的开发具有重要意义,基于体系结构层次的可变性管理可以有效地实现软件的定制和演化。目前体系结构层次的可变性建模并没有得到足够的关注,在分析出领域体系结构后,无法很好地实现体系结构的建模,而且体系结构层次可变性建模方法并没有很好地对可变性的复杂依赖关系进行建模。提出了一种基于多视图的体系结构可变性建模方法,基于UML Profile扩展机制,定义了可变性的构造型、标记值和相关的约束,并利用基于分离的可变性建模方法,定义可变点交互视图对系统中存在的依赖进行建模。基于可变性视图和依赖视图分离的可变性建模方法,实现了复杂依赖关系的有效管理,提高了可变性建模的效果。以船舶故障预测与健康管理系统作为研究案例,对该方法进行了验证,结果表明该方法能够有效地实现软件密集型系统的建模。     

Defining variability in activity diagrams and Petri nets

Control flow models, such as UML activity diagrams or Petri nets, are widely accepted modeling languages used to support quality assurance activities in single system engineering as well as software product line (SPL) engineering. Quality assurance in product line engineering is a challenging task since a defect in a domain artifact may affect several products of the product line. Thus, proper quality assurance approaches need to pay special attention to the product line variability. Automation is essential to support quality assurance approaches. A prerequisite for automation is a profound formalization of the underlying control flow models and, in the context of SPLs, of the variability therein.     

Requirements-driven incremental adoption of variability management techniques and tools: an industrial experience report

In theory, software product line engineering has reached a mature state. In practice though, implementing a variability management approach remains a tough case-by-case challenge for any organization. To tame the complexity of this undertaking, it is inevitable to handle variability from multiple perspectives and to manage variability consistently across artifacts, tools, and workflows. Especially, a solid understanding and management of the requirements to be met by the products is an inevitable prerequisite. In this article, we share experiences from the ongoing incremental adoption of explicit variability management at TRW Automotive’s department for automotive slip control systems—located in Koblenz, Germany. On the technical side, the three key drivers of this adoption effort are (a) domain modeling and scoping, (b) handling of variability in requirements and (c) tighter integration of software engineering focus areas (e.g., domain modeling, requirements engineering, architectural modeling) to make use of variability-related data. In addition to implementation challenges with using and integrating concrete third-party tools, social and workflow-related issues are covered as well. The lessons learned are presented, discussed, and thoroughly compared with the state of the art in research.     

PRONTO: An ontology for comprehensive and consistent representation of product information

Nowadays, it is quite common for collaborating organizations (or even different areas within a company) to develop and maintain their own product model. This situation leads to information duplication and its associated problems. Besides, traditional product models do not properly handle the high number of variants managed in today competitive markets. In addition, there is a need for an integrated product model to be shared by all the organizations participating in global supply chains (SCs) or all the areas within a company. One way to reach an intelligent integration among product models is by means of an ontology. PRoduct ONTOlogy (PRONTO) is an ontology for the product modeling domain, able to efficiently handle product variants. It defines and integrates two hierarchies to represent product information: the abstraction hierarchy (AH) and the structural one (SH). This contribution presents a ConceptBase formal specification of PRONTO that focuses on the structural hierarchy of products. This hierarchy is a tool to handle product information associated with the multiple available recipes or processes to manufacture a particular product or a set of similar products. The formal specification presented in the paper also includes mechanisms to infer structural information from the explicit knowledge represented at each of the AH levels: Family, VariantSet and Product. This proposal efficiently handles a great number of variants and allows representing product information with distinct granularity degrees, which is a requirement for planning activities taking place at different time horizons. PRONTO easily manages crucial features that should be taken into account in a product representation, such as the efficient handling of product families and variants concepts, composition and decomposition structures and the possibility of specifying constraints. To demonstrate the semantic expressiveness of the proposed ontology a food industry related case-study is addressed and discussed in detail.