Feature-oriented Product Lines Research Articles

Template-Based Generator for Single-Choice Questions

Manual composition of tasks and exams is a challenging and time-consuming task. Especially when exams are taken remotely without the personal monitoring by examiners, most exams can easily lose their integrity with the use of previously done exercises or student communication. This research introduces an approach that incorporates the principles of the generative software development and aspects of the feature-oriented product line engineering process into the field of question creation and generation. The resulting generator can be used to generate single-choice-question-families by means of written question templates. The generated questions within a question-family differ based on the set features and parameters and can be imported into the target learning management system ILIAS. Without much effort, examiners and educators can use the generator to create variants of their questions and deliver them to their students.

Properties of a Feature in Code-Assets: An Exploratory Study

Software product line engineering is a paradigm for developing a family of software products from a repository of reusable assets rather than developing each individual product from scratch. In featureoriented software product line engineering, the common and the variable characteristics of the products are expressed in terms of features. Using software product line engineering approach, software products are produced en masse by means of two engineering phases: (i) Domain Engineering and, (ii) Application Engineering. At the domain engineering phase, reusable assets are developed with variation points where variant features may be bound for each of the diverse products. At the application engineering phase, individual and customized products are developed from the reusable assets. Ideally, the reusable assets should be adaptable with less effort to support additional variations (features) that were not planned beforehand in order to increase the usage context of SPL as a result of expanding markets or when a new usage context of software product line emerges. This paper presents an exploration research to investigate the properties of features, in the code-asset implemented using Object-Oriented Programming Style. In the exploration, we observed that program elements of disparate features formed unions as well as intersections that may affect modifiability of the code-assets. The implication of this research to practice is that an unstable product line and with the tendency of emerging variations should aim for techniques that limit the number of intersections between program elements of different features. Similarly, the implication of the observation to research is that there should be subsequent investigations using multiple case studies in different software domains and programming styles to improve the understanding of the findings.

Goal-oriented modeling and verification of feature-oriented product lines

Goal models represent requirements and intentions of a software system. They play an important role in the development life cycle of software product lines (SPLs). In the domain engineering phase, goal models guide the development of variability in SPLs by providing the rationale for the variability, while they are used for the configuration of SPLs in the application engineering phase. However, variability in SPLs, which is represented by feature models, usually has design and implementation-induced constraints. When those constraints are not aligned with variability in goal models, the configuration with goal models becomes error prone. To remedy this problem, we propose a description logic (DL)-based approach to represent both models and their relations in a common DL knowledge base. Moreover, we apply reasoning to detect inconsistencies in the variability of goal and feature models. A formal proof is provided to demonstrate the correctness of the reasoning approach. An empirical evaluation shows computational tractability of the inconsistency detection.

Type safety for feature-oriented product lines

A feature-oriented product line is a family of programs that share a common set of features. A feature implements a stakeholder’s requirement and represents a design decision or configuration option. When added to a program, a feature involves the introduction of new structures, such as classes and methods, and the refinement of existing ones, such as extending methods. A feature-oriented decomposition enables a generator to create an executable program by composing feature code solely on the basis of the feature selection of a user—no other information needed. A key challenge of product line engineering is to guarantee that only well-typed programs are generated. As the number of valid feature combinations grows combinatorially with the number of features, it is not feasible to type check all programs individually. The only feasible approach is to have a type system check the entire code base of the feature-oriented product line. We have developed such a type system on the basis of a formal model of a feature-oriented Java-like language. The type system guaranties type safety for feature-oriented product lines. That is, it ensures that every valid program of a well-typed product line is well-typed. Our formal model including type system is sound and complete.

A feature-oriented approach for developing reusable product line assets of service-based systems

Service orientation (SO) is a relevant promising candidate for accommodating rapidly changing user needs and expectations. One of the goals of adopting SO is the improvement of reusability, however, the development of service-based system in practice has uncovered several challenging issues, such as how to identify reusable services, how to determine configurations of services that are relevant to users’ current product configuration and context, and how to maintain service validity after configuration changes. In this paper, we propose a method that addresses these issues by adapting a feature-oriented product line engineering approach. The method is notable in that it guides developers to identify reusable services at the right level of granularity and to map users’ context to relevant service configuration, and it also provides a means to check the validity of services at runtime in terms of invariants and pre/post-conditions of services. Moreover, we propose a heterogeneous style based architecture model for developing such systems.

특성 지향의 제품계열공학을 위한 애스팩트 구현 패턴

특성 지향 제품계열공학은 특성 관점에서 제품계열의 핵심자산을 개발하고 이를 활용하여 제품을 개발하는 접근방법으로서, 이를 위한 첫번째 단계는 하나의 특성을 하나의 모듈화된 단위로 구현하는 것이다. 관점 지향 프로그래밍은 특성 구현의 모듈화를 향상시키기 위한 효과적인 메커니즘을 제공한다. 하지만, 특성이 일반적으로 서로 독립적이지 않기 때문에 어떤 특성 구현 모듈의 변화는 다른 특성 구현 모듈에 변화를 일으키거나 원하지 않는 부작용을 야기시킬 수도 있다. 뿐만 아니라, 하나의 특성이 제품에 결합되는 시점이 컴파일 시점에서부터 로드 시점, 실행 시점에 이르기까지 다양할 수 있으므로, 특성이 언제 제품에 결합하느냐에 따라 다르게 구현되어야 할지도 모른다. 따라서, 본 논문에서는 각 특성 구현 모듈이 다른 모듈과 독립적이 되도록 하기 위해서, 특성 구현 모듈로부터 특성 의존성 및 특성 결합 시점을 효과적으로 분리시킬 수 있는 애스팩트 패턴을 제안한다. 이러한 패턴들은 특성 구현 모듈이 특성의 선택에 따라서 다른 모듈에 영향을 주지 않고 유연하게 합성될 수 있도록 한다. 이와 같은 접근 방법을 예시하고 평가하기 위해 공학용 계산기 제품계열을 사용한다. Modular implementation of a feature is a first step toward feature-oriented product line engineering, which develops and then utilizes core assets to configure products in terms of features. Aspect-oriented programming provides effective mechanisms for improving the modularity of feature implementations. However, as features in general are not independent of each other, changes in the implementation of one feature may cause changes to or side effects in the implementation of other features. Moreover, since the time at which a feature is incorporated into products, called feature binding time, may be various from compile time through load time to run time, a feature may have to be implemented differently depending on when the feature is bound into a product. To make each feature implementation module as independent as possible, this paper proposes aspectual implementation patterns that can effectively separate feature dependencies as well as feature binding time from feature implementation modules. These patterns enable flexible composition of feature implementation modules without affecting other modules according to feature selection. The approaches are demonstrated and evaluated based on a product line of scientific calculator applications.

Feature-oriented product line engineering

The feature-oriented reuse method analyzes and models a product line's commonalities and differences in terms of product features and uses the analysis results to develop architectures and components. The article illustrates, with a home integration system example, how FORM brings efficiency into product line development.