Carsten Kolassa

First-class variability modeling in Matlab/Simulink

Modern cars exist in an vast number of variants. Thus, variability has to be dealt with in all phases of the development process, in particular during model-based development of software-intensive functionality using Matlab/Simulink. Currently, variability is often encoded within a functional model leading to so called 150%-models which easily become very complex and do not scale for larger product lines. To counter these problems, we propose a modular variability modeling approach for Matlab/Simulink based on the concept of delta modeling [8, 9, 24]. A functional variant is described by a delta encapsulating a set of modifications. A sequence of deltas can be applied to a core product to derive the desired variant. We present a prototypical implementation, which is integrated into Matlab/Simulink and offers graphical editing of delta models.

Engineering delta modeling languages

Delta modeling is a modular, yet flexible approach to capture spatial and temporal variability by explicitly representing the differences between system variants or versions. The conceptual idea of delta modeling is language-independent. But, in order to apply delta modeling for a concrete language, so far, a delta language had to be manually developed on top of the base language leading to a large variety of heterogeneous language concepts. In this paper, we present a process that allows deriving a delta language from the grammar of a given base language. Our approach relies on an automatically generated language extension that can be manually adapted to meet domain-specific needs. We illustrate our approach using delta modeling on a textual variant of statecharts.

Paid vs. Volunteer Work in Open Source

Many open source projects have long become commercial. This paper shows just how much of open source software development is paid work and how much has remained volunteer work. Using a conservative approach, we find that about 50% of all open source software development has been paid work for many years now and that many small projects are fully paid for by companies. However, we also find that any non-trivial project balances the amount of paid developer with volunteer work, and we suggest that the ratio of volunteer to paid work can serve as an indicator for the health of open source projects and aid the management of the respective communities.

A comparison of mechanisms for integrating handwritten and generated code for object-oriented programming languages

Code generation from models is a core activity in model-driven development (MDD). For complex systems it is usually impossible to generate the entire software system from models alone. Thus, MDD requires mechanisms for integrating generated and handwritten code. Applying such mechanisms without considering their effects can cause issues in projects with many model and code artifacts, where a sound integration for generated and handwritten code is necessary. We provide an overview of mechanisms for integrating generated and handwritten code for object-oriented languages. In addition to that, we define and apply criteria to compare these mechanisms. The results are intended to help MDD tool developers in choosing an appropriate integration mechanism.

Integration of Handwritten and Generated Object-Oriented Code

In many development projects models are core artifacts used to generate concrete implementations from them. However, for many systems it is impossible or not useful to generate the complete software system from models alone. Hence, developers need mechanisms for integrating generated and handwritten code. Applying such mechanisms without considering their effects can cause issues in projects, where model and code artifacts are essential. Thus, a sound approach for the integration of both forms of code is needed.

Systematic synthesis of delta modeling languages

Delta modeling is a modular, yet flexible approach to capture variability by explicitly representing differences between system variants or versions. The conceptual idea of delta modeling is language-independent. But, to apply delta modeling to a concrete language, either a generic transformation language has to be used or the corresponding delta language has to be manually developed for each considered base language. Generic languages and their tool support often lack readability and specific context condition checking, since they are unrelated to the base language. In this paper, we present a process that allows synthesizing a delta language from the grammar of a given base language. Our method relies on an automatically generated language extension that can be manually adapted to meet domain-specific needs. We illustrate our method using delta modeling on a textual variant of architecture diagrams. Furthermore, we evaluate our method using a comparative case study. This case study covers an architectural, a structural, and a behavioral language and compares the preexisting handwritten grammars to the generated grammars as well as the manually tailored grammars. This paper is an extension of Haber et al. (Proceedings of the 17th international software product line conference (SPLC’13), pp 22–31, 2013).

Evaluation of Variability Concepts for Simulink in the Automotive Domain

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.