Desain Perangkat Lunak : Konsep dan Tantangannya

Desain perangkat lunak merupakan tahapan pengembangan perangkat lunak yang hasilnya akan digunakan oleh pengembang perangkat lunak untuk membuat program. Dalam tulisan ini, disajikan berbagai konsep penting mengenai desain perangkat lunak, termasuk proses desain itu sendiri. Tulisan ini diakhiri dengan mengkaji berbagai tantangan dalam desain perangkat lunak, dalam hal bagaimana merancang perangkat lunak secara efektif dan perancangan perangkat lunak untuk embedded system. Dari kajian tersebut diharapkan memicu riset-riset dalam desain perangkat lunak

The learning of sociotechnical practices in embedded systems development

Embedded systems are an important element of controlling wind turbines. Embedded systems development and learning are inseparable. This paper presents a study of wind turbine control systems and the developers’ learning with the hope of contributing to the understanding of embedded systems development and practice-based learning. Our approach focuses on the sociotechnical practices, including the reciprocity between constitutive means and the developers’ individual experience; central matters in this framework involve the process of understanding the indeterminacy and the handling of the IT. The embedded systems development case addresses development of hardware, software and their interfaces. Learning occurs, enabled by converging understanding of the indeterminate situation and the different experience of the developers. The case shows that embedded systems developers deliberately keep technical knowledge close to their chests, which constrains learning. The paper contributes to the understanding of the individual systems developer’s learning and the mechanisms of enablers and obstacles in the learning processes

A software integration approach for designing and assessing dependable embedded systems

Embedded systems increasingly entail complex issues of hardware-software (HW-SW) co-design. As the number and range of SW functional components typically exceed the finite HW resources, a common approach is that of resource sharing (i.e., the deployment of diverse SW functionalities onto the same HW resources). Consequently, to result in a meaningful co-design solution, one needs to factor the issues of processing capability, power, communication bandwidth, precedence relations, real-time deadlines, space, and cost. As SW functions of diverse criticality (e.g. brake control and infotainment functions) get integrated, an explicit integration requirement need is to carefully plan resource sharing such that faults in low-criticality functions do not affect higher-criticality functions. On this background, the main contribution of this paper is a dependability-driven framework that helps to conduct the integration of SW components onto HW resources such that the maintenance of system dependability over integration of diverse criticality components is assured by design. We first develop a clustering strategy for SW components into Fault Containment Modules (FCMs) such that error propagation via interaction is minimized. Subsequently, the rules of composition for FCMs with respect to error propagation are developed. To allocate the resulting FCMs to the existing HW resources we provide several heuristics, each optimizing particular attributes thereof. Further, a framework for assessing the goodness of the achieved HW-SW composition as a dependable embedded system is presented. Two new techniques for quantifying the goodness of the proposed mappings are introduced by examples, both based on a multi-criteria decision theoretic approach. (C) 2010 Elsevier Inc. All rights reserved

Placement, ordonnancement et mécanismes de migration de tâches temps-réel pour des architectures distribuées multicoeurs

Les systèmes temps-réel embarqués critiques intègrent un nombre croissant de fonctionnalités comme le montrent les domaines de l'automobile ou de l'aéronautique. Ces systèmes doivent offrir un niveau maximal de sûreté de fonctionnement en disposant des mécanismes pour traiter les défaillances éventuelles et doivent être également performants, avec le respect de contraintes temps-réel strictes. Ces systèmes sont en outre contraints par leur nature embarquée : les ressources sont limitées, tels que par exemple leur espace mémoire et leur capacité de calcul. Dans cette thèse, nous traitons deux problématiques principales de ce type de systèmes. La première porte sur la manière d'apporter une meilleure tolérance aux fautes dans les systèmes temps-réel distribués subissant des défaillances matérielles multiples et permanentes. Ces systèmes sont souvent conçus avec une allocation statique des tâches. Une approche plus exible effectuant des recon gurations est utile si elle permet d'optimiser l'allocation à chaque défaillance rencontrée, pour les ressources restantes. Nous proposons une telle approche hors-ligne assurant un dimensionnement adapté pour prendre en compte les ressources nécessaires à l'exécution de ces actions. Ces recon gurations peuvent demander une réallocation des tâches ou répliques si l'espace mémoire local est limité. Dans un contexte temps-réel strict, nous dé nissons notamment des mécanismes et des techniques de migration garantissant l'ordonnançabilité globale du système. La deuxième problématique se focalise sur l'optimisation de l'exécution des tâches au niveau local dans un contexte multicoeurs préemptif. Nous proposons une méthode d'ordonnancement optimal disposant d'une meilleure extensibilité que les approches existantes en minimisant les surcoûts : le nombre de changements de contexte préemptions et migrations locales) et la complexité de l'ordonnanceurCritical real-time embedded systems are integrating an increasing number of functionalities, as shown in automotive domain or aeronautics. These systems require high dependability including mechanisms to handle possible failures and have to be effective, meeting hard real-time constraints. These systems are also constrained by their embedded nature : resources are limited, such as their memory and their computing capacities. In this thesis, we focus on two main problems for this type of systems. The rst one is about a way to bring a better fault-tolerance in distributed real-time systems when multiple and permanent hardware failures can occur. In classical systems, the design is limited to a static task assignment. A more exible approach exploiting recon gurations is useful if it allows to optimize assignment at each failure for the remaining resources. We propose an off-line approach to obtain an adapted sizing taking into account necessary resources to execute these actions. These recon gurations may require to reallocate tasks or replicas if memory capacities are limited. In a hard real-time context, we de ne mechanisms and migration techniques to guarantee global schedulability of the system. The second problem focus on optimizing performance to run tasks at a local level in a multicore preemptive context. We propose an optimal scheduling method allowing a better scalability than existing approaches by minimizing overheads : the number of context switches (local preemptions and migrations) and the scheduler complexityTOULOUSE-INP (315552154) / SudocSudocFranceF

Placement, ordonnancement et mécanismes de migration de tâches temps-réel pour des architectures distribuées multicoeurs

Les systèmes temps-réel embarqués critiques intègrent un nombre croissant de fonctionnalités comme le montrent les domaines de l'automobile ou de l'aéronautique. Ces systèmes doivent offrir un niveau maximal de sûreté de fonctionnement en disposant des mécanismes pour traiter les défaillances éventuelles et doivent être également performants, avec le respect de contraintes temps-réel strictes. Ces systèmes sont en outre contraints par leur nature embarquée : les ressources sont limitées, tels que par exemple leur espace mémoire et leur capacité de calcul. Dans cette thèse, nous traitons deux problématiques principales de ce type de systèmes. La première porte sur la manière d'apporter une meilleure tolérance aux fautes dans les systèmes temps-réel distribués subissant des défaillances matérielles multiples et permanentes. Ces systèmes sont souvent conçus avec une allocation statique des tâches. Une approche plus flexible effectuant des reconfigurations est utile si elle permet d'optimiser l'allocation à chaque défaillance rencontrée, pour les ressources restantes. Nous proposons une telle approche hors-ligne assurant un dimensionnement adapté pour prendre en compte les ressources nécessaires à l'exécution de ces actions. Ces reconfigurations peuvent demander une réallocation des tâches ou répliques si l'espace mémoire local est limité. Dans un contexte temps-réel strict, nous définissons notamment des mécanismes et des techniques de migration garantissant l'ordonnançabilité globale du système. La deuxième problématique se focalise sur l'optimisation de l'exécution des tâches au niveau local dans un contexte multicoeurs préemptif. Nous proposons une méthode d'ordonnancement optimal disposant d'une meilleure extensibilité que les approches existantes en minimisant les surcoûts : le nombre de changements de contexte préemptions et migrations locales) et la complexité de l'ordonnanceur. ABSTRACT : Critical real-time embedded systems are integrating an increasing number of functionalities, as shown in automotive domain or aeronautics. These systems require high dependability including mechanisms to handle possible failures and have to be effective, meeting hard real-time constraints. These systems are also constrained by their embedded nature : resources are limited, such as their memory and their computing capacities. In this thesis, we focus on two main problems for this type of systems. The first one is about a way to bring a better fault-tolerance in distributed real-time systems when multiple and permanent hardware failures can occur. In classical systems, the design is limited to a static task assignment. A more flexible approach exploiting reconfigurations is useful if it allows to optimize assignment at each failure for the remaining resources. We propose an off-line approach to obtain an adapted sizing taking into account necessary resources to execute these actions. These reconfigurations may require to reallocate tasks or replicas if memory capacities are limited. In a hard real-time context, we define mechanisms and migration techniques to guarantee global schedulability of the system. The second problem focus on optimizing performance to run tasks at a local level in a multicore preemptive context. We propose an optimal scheduling method allowing a better scalability than existing approaches by minimizing overheads : the number of context switches (local preemptions and migrations) and the scheduler complexity

Applying patterns in embedded systems design for managing quality attributes and their trade-offs

Embedded systems comprise one of the most important types of software-intensive systems, as they are pervasive and used in daily life more than any other type, e.g., in cars or in electrical appliances. When these systems operate under hard constraints, the violation of which can lead to catastrophic events, the system is classified as a critical embedded system (CES). The quality attributes related to these hard constraints are named critical quality attributes (CQAs). For example, the performance of the software for cruise-control or self-driving in a car are critical as they can potentially relate to harming human lives. Despite the growing body of knowledge on engineering CESs, there is still a lack of approaches that can support its design, while managing CQAs and their trade-offs with noncritical ones (e.g., maintainability and reusability). To address this gap, the state-of-research and practice on designing CES and managing quality trade-offs were explored, approaches to improve its design identified, and the merit of these approaches empirically investigated. When designing software, one common approach is to organize its components according to well-known structures, named design patterns. However, these patterns may be avoided in some classes of systems such as CES, as they are sometimes associated with the detriment of CQAs. In short, the findings reported in the thesis suggest that, when applicable, design patterns can promote CQAs while supporting the management of trade-offs. The thesis also reports on a phenomena, namely pattern grime, and factors that can influence the extent of the observed benefits