Michiel Helvensteijn

Abstract delta modeling

Delta modeling is an approach to facilitate automated product derivation for software product lines. It is based on a set of deltas specifying modifications that are incrementally applied to a core product. The applicability of deltas depends on feature-dependent conditions. This paper presents abstract delta modeling, which explores delta modeling from an abstract, algebraic perspective. Compared to previous work, we take a more flexible approach with respect to conflicts between modifications and introduce the notion of conflict-resolving deltas. We present conditions on the structure of deltas to ensure unambiguous product generation.

Abstract delta modelling

Delta modelling is an approach to facilitate the automated product derivation for software product lines. It is based on a set of deltas specifying modifications that are incrementally applied to a core product. The applicability of deltas depends on application conditions over features. This paper presents abstract delta modelling , which explores delta modelling from an abstract, algebraic perspective. Compared to the previous work, we take a more flexible approach to conflicts between modifications by introducing the notion of conflict-resolving deltas. Furthermore, we extend our approach to allow the nesting of delta models for increased modularity. We also present conditions on the structure of deltas to ensure unambiguous product generation.

Delta modeling in practice: a Fredhopper case study

Delta modeling is a method for modeling software product lines (SPL), which supports the automated derivation of products. ABS is a recent modeling language and accompanying toolset that implements delta modeling as its core paradigm for developing variable systems. Due to its novelty, delta modeling has so far seen little practical application. However, only practical evaluation can indicate to what extent the delta modeling methodology is suited for the efficient and accurate modeling and implementation of SPLs. This paper reports on the development of an industrial scale product line in ABS following a workflow that guides the application of delta modeling in practice. By following the delta modeling workflow (DMW), we show how conflicting feature functionality can be systematically reconciled, and how DMW guides the implementation towards a globally unambiguous and complete product line. We further explain how this experience has been used to refine the workflow and its support by the ABS language.

HATS abstract behavioral specification: the architectural view

The Abstract Behavioral Specification (ABS) language is a formal, executable, object-oriented, concurrent modeling language intended for behavioral modeling of complex software systems that exhibit a high degree of variation, such as software product lines. We give an overview of the architectural aspects of ABS: a feature-driven development workflow, a formal notion of deployment components for specifying environmental constraints, and a dynamic component model that is integrated into the language. We employ an industrial case study to demonstrate how the various aspects work together in practice.

Dynamic delta modeling

Abstract Delta Modeling (ADM) offers an algebraic description of how a (software) product line may be built so that every product can be automatically derived by structured reuse of code. In traditional application engineering a single valid feature configuration is chosen, which does not change during the lifetime of the product. However, there are many useful applications for product lines that change their configuration at run time. We present a new technique for generating efficient dynamic product lines from their static counterparts. We use Mealy machines for their dynamic reconfiguration. Furthermore, we posit that monitoring some features will be more expensive than monitoring others, and present techniques for minimizing the cost of monitoring the system. We stay in the abstract setting of ADM but the techniques can be instantiated to any concrete domain. We illustrate them through the example of a mobile application for Android, which dynamically reconfigures a devices operating profile based on environmental factors.

Delta modeling workflow

In previous work we show how abstract delta modeling can be used to model product lines. The formalism assigns a functional meaning to features from a feature model and provides a novel mechanism for resolving implementation conflicts without code duplication or overspecification. But in the vast expressive space of delta modeling, it may not be clear to a developer how to create a product line from scratch. The formalism was descriptive rather than prescriptive. To that end, we propose a development workflow based directly on Abstract Delta Modeling. We show preservation of global unambiguity and completeness in the product lines resulting from this workflow. We also show that the work-flow naturally supports concurrent development.

The Open Physiology workflow: modeling processes over physiology circuitboards of interoperable tissue units.

A key challenge for the physiology modeling community is to enable the searching, objective comparison and, ultimately, re-use of models and associated data that are interoperable in terms of their physiological meaning. In this work, we outline the development of a workflow to modularize the simulation of tissue-level processes in physiology. In particular, we show how, via this approach, we can systematically extract, parcellate and annotate tissue histology data to represent component units of tissue function. These functional units are semantically interoperable, in terms of their physiological meaning. In particular, they are interoperable with respect to [i] each other and with respect to [ii] a circuitboard representation of long-range advective routes of fluid flow over which to model long-range molecular exchange between these units. We exemplify this approach through the combination of models for physiology-based pharmacokinetics and pharmacodynamics to quantitatively depict biological mechanisms across multiple scales. Links to the data, models and software components that constitute this workflow are found at http://open-physiology.org/.

Requirements for the formal representation of pathophysiology mechanisms by clinicians

Knowledge of multiscale mechanisms in pathophysiology is the bedrock of clinical practice. If quantitative methods, predicting patient-specific behaviour of these pathophysiology mechanisms, are to be brought to bear on clinical decision-making, the Human Physiome community and Clinical community must share a common computational blueprint for pathophysiology mechanisms. A number of obstacles stand in the way of this sharing—not least the technical and operational challenges that must be overcome to ensure that (i) the explicit biological meanings of the Physiomes quantitative methods to represent mechanisms are open to articulation, verification and study by clinicians, and that (ii) clinicians are given the tools and training to explicitly express disease manifestations in direct contribution to modelling. To this end, the Physiome and Clinical communities must co-develop a common computational toolkit, based on this blueprint, to bridge the representation of knowledge of pathophysiology mechanisms (a) that is implicitly depicted in electronic health records and the literature, with (b) that found in mathematical models explicitly describing mechanisms. In particular, this paper makes use of a step-wise description of a specific disease mechanism as a means to elicit the requirements of representing pathophysiological meaning explicitly. The computational blueprint developed from these requirements addresses the Clinical community goals to (i) organize and manage healthcare resources in terms of relevant disease-related knowledge of mechanisms and (ii) train the next generation of physicians in the application of quantitative methods relevant to their research and practice.

ApiNATOMY: Towards Multiscale Views of Human Anatomy

Physiology experts deal with complex biophysical relationships, across multiple spatial and temporal scales. Automating the discovery of such relationships, in terms of physiological meaning, is a key goal to the physiology community. ApiNATOMY is an effort to provide an interface between the physiology expert’s knowledge and all ranges of data relevant to physiology. It does this through an intuitive graphical interface for managing semantic metadata and ontologies relevant to physiology. In this paper, we present a web-based ApiNATOMY environment, allowing physiology experts to navigate through circuitboard visualizations of body components, and their cardiovascular and neural connections, across different scales. Overlaid on these schematics are graphical renderings of organs, neurons and gene products, as well as mathematical models of processes semantically annotated with this knowledge.

A modal logic for abstract delta modeling

Abstract Delta Modeling is a technique for implementing (software) product lines. Deltas are placed in a partial order which restricts their application and are then sequentially applied to a core product in order to form specific products in the product line. In this paper we explore the semantics of deltas in more detail. We regard them as relations between products and introduce a multimodal logic that may be used for reasoning about their effects. Our main innovation is a modality for partially ordered sets of deltas. We prove completeness results on both the frame level and the model level and demonstrate the logic through an example.