Holger Rendel

Carsten Kolassa, Holger Rendel, Bernhard Rumpe

Modeling variability in Matlab/Simulink becomes more and more important. We took the two variability modeling concepts already included in Matlab/Simulink and our own one and evaluated them to find out which one is suited best for modeling variability in the automotive domain. We conducted a controlled experiment with developers at Volkswagen AG to decide which concept is preferred by developers and if their preference aligns with measurable performance factors. We found out that all existing concepts are viable approaches and that the delta approach is both the preferred concept as well as the objectively most efficient one, which makes Delta-Simulink a good solution to model variability in the automotive domain.

Christian Berger, Holger Rendel, Bernhard Rumpe

A product line approach can save valuable resources by reusing artifacts. Especially for software artifacts, the reuse of existing components is highly desirable. In recent literature, the creation of software product lines is mainly proposed from a top-down point of view regarding features which are visible by customers. In practice, however, the design for a product line often arises from one or few existing products that descend from a very first product starting with copy-paste and evolving individually. In this contribution, we propose the theoretical basis to derive a set of metrics for evaluating similar software products in an objective manner. These metrics are used to evaluate the set of product's ability to form a product line.

Christian Berger, Holger Rendel, Bernhard Rumpe et al.

Nowadays, customer products like vehicles do not only contain mechanical parts but also a highly complex software and their manufacturers have to offer many variants of technically very similar systems with sometimes only small differences in their behavior. The proper reuse of software artifacts which realize this behavior using a software product line is discussed in recent literature and appropriate methods and techniques for their management are proposed. However, establishing a software product line for integrating already existing legacy software to reuse valuable resources for future similar products is very company-specific. In this paper, a method is outlined for evaluating objectively a legacy software's potential to create a software product line. This method is applied to several development projects at Volkswagen AG Business Unit Braunschweig to evaluate the software product line potential for steering systems.

Arne Haber, Holger Rendel, Bernhard Rumpe et al.

Architectural modeling is an integral part of modern software development. In particular, diverse systems benefit from precise architectural models since similar components can often be reused between different system variants. However, during all phases of diverse system development, system variability has to be considered and modeled by appropriate means. Delta modeling is a language-independent approach for modeling system variability. A set of diverse systems is represented by a core system and a set of deltas specifying modifications to the core system. In this paper, we give a first sketch of how to apply delta modeling in MontiArc, an existing architecture description language, in order to obtain an integrated modeling language for architectural variability. The developed language, MontiArc, allows the modular modeling of variable software architectures and supports proactive as well as extractive product line development.

Arne Haber, Thomas Kutz, Holger Rendel et al.

Modeling of software architectures is a fundamental part of software development processes. Reuse of software components and early analysis of software topologies allow the reduction of development costs and increases software quality. Integrating variability modeling concepts into architecture description languages (ADLs) is essential for the development of diverse software systems with high demands on software quality. In this paper, we present the integration of delta modeling into the existing ADL MontiArc. Delta modeling is a language-independent variability modeling approach supporting proactive, reactive and extractive product line development. We show how ?-MontiArc, a language for explicit modeling of architectural variability based on delta modeling, is implemented as domain-specific language (DSL) using the DSL development framework MontiCore. We also demonstrate how MontiCore's language reuse mechanisms provide efficient means to derive an implementation of ?-MontiArc tool implementation. We evaluate ?-Monti-Arc by comparing it with annotative variability modeling.

Arne Haber, Thomas Kutz, Holger Rendel et al.

Modeling variability in software architectures is a fundamental part of software product line development. ?-MontiArc allows describing architectural variability in a modular way by a designated core architecture and a set of architectural delta models modifying the core architecture to realize other architecture variants. Delta models have to satisfy a set of applicability conditions for the definedness of the architectural variants. The applicability conditions can in principle be checked by generating all possible architecture variants, which requires considering the same intermediate architectures repeatedly. In order to reuse previously computed architecture variants, we propose a family-based analysis of the applicability conditions using the concept of inverse deltas.