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.     

Managing requirements conflicts in software product lines: A goal and scenario based approach

The product line approach is recognized as a successful approach to reuse in software development. However, in many cases, it has resulted in interactions between requirements and/or features. Interaction detection, especially conflict detection between requirements has become more challenging. Thus, detecting conflicts between requirements is essential for successful product line development. Formal methods have been proposed to address this problem, however, they are hard to understand by non-experts and are limited to restricted domains. In addition, there is no overall process that covers all the steps for managing conflicts. We propose an approach for systematically identifying and managing requirements conflicts, which is based on requirements partition in natural language and supported by a tool. To demonstrate its feasibility, the proposed approach has been applied to the home integration system (HIS) domain and the results are discussed.     

A case-;study of requirements reuse through product families

Increasingly, software organisations are looking towards large-;scale reuse as a way of improving productivity, raising quality and reducing delivery timescales. Many in the reuse community have suggested notions of product-;line development and domain engineering life-;cycles. Achieving these in practice, however, requires a systematic process for “early” reuse (requirements reuse) as well as late reuse (code reuse). This paper discusses pratical experience of early reuse. We describe FORE (Family Of REquirements), an approach that we have developed in our work in the domain of aircraft engine control systems. The FORE approach concentrates on the definition of a generic product concept and the formalisation of its requirements. We describe the FORE approach in general terms, and then show how it has been applied in an industrial case-;study. We make an initial evaluation of the FORE approach (and early reuse in general) in terms of how it has changed an existing requirements engineering process. We compare the FORE approach to related work in early reuse, and draw some conclusions about how the approach may scale to other problems.     

基于UML用例图的软件产品线需求建模方法

软件产品线方法是一种面向特定领域的、大规模、大粒度的软件复用技术。明确建模和描述软件产品线需求是软件产品线开发的关键问题之一。而传统的UML用例图等方法不足以完整描述产品线需求,特别是其变化性。通过分析软件产品线开发过程和软件产品线需求建模的特殊性,采用扩展UML用例图标签的方法,实现对软件产品线需求的明确描述。以网络图书销售软件产品线为例,进行具体说明。     

An approach to developing domain requirements as a core asset based on commonality and variability analysis in a product line

The methodologies of product line engineering emphasize proactive reuse to construct high-quality products more quickly that are less costly. Requirements engineering for software product families differs significantly from requirements engineering for single software products. The requirements for a product line are written for the group of systems as a whole, with requirements for individual systems specified by a delta or an increment to the generic set. Therefore, it is necessary to identify and explicitly denote the regions of commonality and points of variation at the requirements level. In this paper, we suggest a method of producing requirements that will be a core asset in the product line. We describe a process for developing domain requirements where commonality and variability in a domain are explicitly considered. A CASE environment, named DREAM, for managing commonality and variability analysis of domain requirements is also described. We also describe a case study for an e-travel system domain where we found that our approach to developing domain requirements based on commonality and variability analysis helped to produce domain requirements as a core asset for product lines.     

Deriving engineering software from requirements

With the advent of intelligent computer aided design systems, companies such as Boeing are embarking on an era in which core competitive engineering knowledge and design rationale is being encoded in software systems. The promise of this technology is that this knowledge can be leveraged across many different designs, product families, and even different uses (e.g., generative process planning for manufacturing). The current state of the practice attempts to achieve this goal through the reuse of software components. A fundamental problem with this approach to knowledge sharing and reuse is that what we are trying to reuse is software—the end artifact in a long and complicated process that goes from requirement specifications, through a process of design, to implementations. Knowledge sharing and reuse can not easily and uniformly occur at the software level. So what can be done as an alternative? This paper describes a theory, methodology, language, and tool for the semi-automatic development and maintenance of engineering software from requirement specifications. In essence, this paradigm for software development and maintenance is one that explicitly captures requirement specifications, designs, implementations, and the refinement processes that lead from requirements all the way down to software. By recording this entire refinement history, we stand a better chance of leveraging knowledge for different uses.     

A Knowledge-Based Software Engineering Environment for reusable software requirements and architectures

This paper describes a prototype Knowledge-Based Software Engineering Environment used to demonstrate the concepts of reuse of software requirements and software architectures. The prototype environment, which is application-domain independent, is used to support the development of domain models and to generate target system specifications from them. The prototype environment consists of an integrated set of commercial-off-the-shelf software tools and custom developed software tools.The concept of reuse is prevalent at several levels of the domain modeling method and prototype environment. The environment itself is domain-independent thereby supporting the specification of diverse application domain models. The domain modeling method specifies a family of systems rather than a single system; features characterize the variations in functional requirements supported by the family and individual family members are specified by the features they are to support. The knowledge-based approach to target system generation provides the rules for generating target system specifications from the domain model; target system specifications, themselves, may be stored in an object repository for subsequent retrieval and reuse.     

Dynamic decision models for staged software product line configuration

Software product line engineering practices offer desirable characteristics such as rapid product development, reduced time-to-market, and more affordable development costs as a result of systematic representation of the variabilities of a domain of discourse that leads to methodical reuse of software assets. The development lifecycle of a product line consists of two main phases: domain engineering, which deals with the understanding and formally modeling of the target domain, and application engineering that is concerned with the configuration of a product line into one concrete product based on the preferences and requirements of the stakeholders. The work presented in this paper focuses on the application engineering phase and builds both the theoretical and technological tools to assist the stakeholders in (a) understanding the complex interactions of the features of a product line; (b) eliciting the utility of each feature for the stakeholders and hence exposing the stakeholders’ otherwise implicit preferences in a way that they can more easily make decisions; and (c) dynamically building a decision model through interaction with the stakeholders and by considering the structural characteristics of software product line feature models, which will guide the stakeholders through the product configuration process. Initial exploratory empirical experiments that we have performed show that our proposed approach for helping stakeholders understand their feature preferences and its associated staged feature model configuration process is able to positively impact the quality of the end results of the application engineering process within the context of the limited number of participants. In addition, it has been observed that the offered tooling support is able to ease the staged feature model configuration process.     

Saving reuse from the noose: reuse of analogous specifications through human involvement in reuse process

Analogy is proposed as an alternative paradigm for the reuse of specifications during requirements analysis. First, critical determinants of analogies between software engineering problems are discussed in relation to a specification retrieval mechanism. Second, the process of specification reuse is examined. Specification reuse by analogy is knowledge-intensive, hence an important role is proposed for the analyst during specification reuse: analyst involvement would appear necessary to categorize a new problem, select between candidate reusable specifications, and customize the selected specification to the new domain. Finally, a specification reuse tool is proposed that recognises the collaborative nature of reuse by analogy. This tool assists and advises the analyst during reuse founded on cognitive models of analyst behaviour during analogous reasoning and reuse. The prototype version of this intelligent reuse advisor (Ira) is outlined.     

Requirements engineering in software product line engineering

Many attempts have been made to increase the productivity and quality of software products based on software reuse. Software product line practice is one such approach, one that focuses on developing a family of products which have a majority of features in common. Hence, there are numerous requirements that are common across the family, but others are unique to individual products. Traditional requirements engineering methods were conceived to deal with single product requirements and are usually not flexible enough to address the needs arising from reusing requirements for a family of products. There is also the additional burden of correctly identifying and engineering both product-line-wide requirements and product-specific requirements as well as evolving them. Therefore, in this special issue, we want to highlight the importance and the role of requirements engineering for product line development as well as to provide insights into the state of the art in the field.     

基于产品线工程方法提高组件容器的可复用性

组件容器为组件提供部署和运行环境,是基于组件的分布式应用开发的核心。近年来,开发网构软件的需求驱动着组件技术持续改进,新型组件不断涌现,这对组件容器的开发效率提出更高的要求。因此,在组件容器开发过程中大规模复用已有的软件资产变得非常重要。在许多情况下,产品线工程已被证实是有效的系统化复用的工程方法。首先探讨将产品线工程应用于组件容器开发所面临的主要困难,并提出相应的解决方案;然后给出了一个组件容器的产品线——PLACE的设计,解释了其两个主要部分:产品线体系结构和产品派生流程;最后,通过一个实际案例,展示利用PLACE设计开发组件容器的完整过程,结果证实体系结构和源代码的复用性都有一定程度的提高。     

Empirical assessment of two approaches for specifying software product line use case scenarios

Modularity benefits, including the independent maintenance and comprehension of individual modules, have been widely advocated. However, empirical assessments to investigate those benefits have mostly focused on source code, and thus, the relevance of modularity to earlier artifacts is still not so clear (such as requirements and design models). In this paper, we use a multimethod technique, including designed experiments, to empirically evaluate the benefits of modularity in the context of two approaches for specifying product line use case scenarios: PLUSS and MSVCM. The first uses an annotative approach for specifying variability, whereas the second relies on aspect-oriented constructs for separating common and variant scenario specifications. After evaluating these approaches through the specifications of several systems, we find out that MSVCM reduces feature scattering and improves scenario cohesion. These results suggest that evolving a product line specification using MSVCM requires only localized changes. On the other hand, the results of six experiments reveal that MSVCM requires more time to derive the product line specifications and, contrasting with the modularity results, reduces the time to evolve a product line specification only when the subjects have been well trained and are used to the task of evolving product line specifications.     

XTraQue: traceability for product line systems

Product line engineering has been increasingly used to support the development and deployment of software systems that share a common set of features and are developed based on the reuse of core assets. The large number and heterogeneity of documents generated during the development of product line systems may cause difficulties to identify common and variable aspects among applications, and to reuse core assets that are available under the product line. In this paper, we present a traceability approach for product line systems. Traceability has been recognised as an important task in software system development. Traceability relations can improve the quality of the product being developed and reduce development time and cost. We present a rule-based approach to support automatic generation of traceability relations between feature-based object-oriented documents. We define a traceability reference model with nine different types of traceability relations for eight types of documents. The traceability rules used in our work are classified into two groups namely (a) direct rules, which support the creation of traceability relations that do not depend on the existence of other relations, and (b) indirect rules, which require the existence of previously generated relations. The documents are represented in XML and the rules are represented in an extension of XQuery. A prototype tool called XTraQue has been implemented. This tool, together with a mobile phone product line case study, has been used to demonstrate and evaluate our work in various experiments. The results of these experiments are encouraging and comparable with other approaches that support automatic generation of traceability relations. This work has been partially supported by Dhurakijpundit University, Thailand.     

Fuzzy logic as a basis for reusing task-based specifications

In this paper, we propose an approach to reusing requirements specification, called task-based specifications in conceptual graphs (TBCG). In TBCG, task-based specification methodology is used to serve as the mechanism to structure the knowledge captured in conceptual models, and conceptual graphs are adopted as the formalism to express requirements specification. TBCG provides several mechanisms to facilitate the reuse of formal specifications: a contextual retrieval mechanism to support context-sensitive specifications retrieval and incremental context acquisition, a graph matching mechanism to compute the similarity between two graphs based on the semantic match and fuzzy logic, and a paraphraser to serve as an explanation mechanism for the retrieval specifications. ©1999 John Wiley & Sons, Inc.     

Specifying software quality with the extended ISO model

Specifying the quality of software products is a valuable addition to functional specification, clarifying product properties such as learnability and availability. Specifying such properties is considered difficult due to the different parties involved and the implicit nature of the requirements. The QUINT project gathered experience with product specification by means of the Extended ISO model: an extension to the ISO 9126 model of software quality. By defining indicators and specifying how they should be measured, quality specifications can make requirements explicit. Recommendations and pitfalls for composing a specification are grouped by the context in which quality specifications can be used.     

A holistic approach to feature modeling for product line requirements engineering

Requirements engineering (RE) offers the means to discover, model, and manage the requirements of the products that comprise a product line, while software product line engineering (SPLE) offers the means of realizing the products’ requirements from a common base of software assets. In practice, however, RE and SPLE have proven to be less complementary than they should. While some RE techniques, particularly goal modeling, support the exploration of alternative solutions, the appropriate solution is typically conditional on context and a large product line may have many product-defining contexts. Thus, scalability and traceability through into product line features are key challenges for RE. Feature modeling, by contrast, has been widely accepted as a way of modeling commonality and variability of products of a product line that may be very complex. In this paper, we propose a goal-driven feature modeling approach that separates a feature space in terms of problem space and solution space features, and establish explicit mappings between them. This approach contributes to reducing the inherent complexity of a mixed-view feature model, deriving key engineering drivers for developing core assets of a product line, and facilitating the quality-based product configuration.     

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.     

从领域需求到产品线体系结构的映射——一种面向特征的方法

领域需求之间的依赖关系对软件产品线的体系结构有很大的影响,在已有的面向特征的管理产品线需求依赖的方法中很少有研究从需求到产品线体系结构的映射.基于一种特征依赖的分类方法,提出了从领域需求到特征,以及从特征到产品线体系结构的映射规则.通过这些映射规则,一致的需求通过映射得到一致的产品线核心资产,从而减少产品线中核心资产的不一致性并增加产品线的复用程度.用金融领域的现货交易产品线作为实例说明这个方法的实用性.     

Automating the product derivation process of multi-agent systems product lines

Agent-oriented software engineering and software product lines are two promising software engineering techniques. Recent research work has been exploring their integration, namely multi-agent systems product lines (MAS-PLs), to promote reuse and variability management in the context of complex software systems. However, current product derivation approaches do not provide specific mechanisms to deal with MAS-PLs. This is essential because they typically encompass several concerns (e.g., trust, coordination, transaction, state persistence) that are constructed on the basis of heterogeneous technologies (e.g., object-oriented frameworks and platforms). In this paper, we propose the use of multi-level models to support the configuration knowledge specification and automatic product derivation of MAS-PLs. Our approach provides an agent-specific architecture model that uses abstractions and instantiation rules that are relevant to this application domain. In order to evaluate the feasibility and effectiveness of the proposed approach, we have implemented it as an extension of an existing product derivation tool, called GenArch. The approach has also been evaluated through the automatic instantiation of two MAS-PLs, demonstrating its potential and benefits to product derivation and configuration knowledge specification.     

The role of polymorphic reuse mechanisms in schema evolution in anobject-oriented database

A seamless approach to the incremental design and reuse of object oriented methods and query specifications is presented. We argue for avoiding or minimizing the effort required for manually reprogramming methods and queries due to schema modifications, and demonstrate how the role of polymorphic reuse mechanisms is exploited for enhancing the adaptiveness of database programs against schema evolution in an object oriented database. The salient features of our approach are the use of propagation patterns and a mechanism for propagation pattern refinement. Propagation patterns are employed as an interesting specification formalism for modeling operational requirements. They encourage the reuse of operational specifications against the structural modification of an object oriented schema. Propagation pattern refinement is suited for the specification of reusable operational modules. It promotes the reusability of propagation patterns toward the operational requirement changes. This approach has a formal basis and emphasizes structural derivation of specifications. The main innovations are in raising the level of abstraction for behavioral schema design, and for making possible the derivation of operational semantics from structural specifications. As a result, both the modularity and reusability of object oriented schemas are increased