Nobody’s perfect: interactive synthesis from parametrized real-time scenarios

ABSTRACT As technical systems keep growing more complex and sophisticated, designing software for the safety-critical coordination between their components becomes increasingly difficult. Verifying and correcting these components already represents a significant part of the development process both with respect to time and cost. Scenario-based synthesis has been put forward as an approach to accelerate the transition from requirements to a correct, verified model. I

A Collaboration-based Approach to Service Specification and Detection of Implied Scenarios

ABSTRACT Methods for service specification should be simple and intuitive. At the same time they should be precise and allow early validations to be performed, in order to detect inconsistencies as early as possible in the service development cycle. In this paper we present a service specification approach based on UML 2.0 collaborations. It aims to be a constructive approach, rather than a corrective one, as it is intended to promote understanding and help reducing the number of specification errors. We also address the detection of implied scenarios from collaboration-based service specifications, and propose an approach that limits the state explosion problem. This is possible since the detection analysis is modular and it is performed at a high-level of abstraction

Seismic Assessment and Retrofit of Reinforced Concrete Structures

Many constructions are built with reinforced or prestressed concrete, and most of them are designed or expected to resist earthquake actions in addition to gravity loads. To limit the effects of seismic events on reinforced or prestressed concrete structures, many attempts have been made by researchers in order to (i) improve the knowledge of the response of materials (steel bars and concrete) and members by means of laboratory tests, (ii) develop numerical and capacity models, (iii) enhance procedures for the dynamic analysis and assessment of the seismic performance of structures and (iv) suggest innovative interventions for the seismic retrofit of old and damaged reinforced or prestressed concrete structures. This Special Issue is a collection of 11 important research works that cover a wide range of problems related to the previously mentioned research fields. Both researchers and practical engineers are expected to greatly benefit from this Special Issue in view of their own work and for a better comprehension of the response of r.c. members and structures

Eighth Workshop and Tutorial on Practical Use of Coloured Petri Nets and the CPN Tools, Aarhus, Denmark, October 22-24, 2007

This booklet contains the proceedings of the Eighth Workshop on Practical Use of Coloured Petri Nets and the CPN Tools, October 22-24, 2007. The workshop is organised by the CPN group at the Department of Computer Science, University of Aarhus, Denmark. The papers are also available in electronic form via the web pages: http://www.daimi.au.dk/CPnets/workshop0

Intégration de la modélisation comportementale dans la conception par points de vue

View-based modeling is the main subject of this thesis. It is a variant of the object oriented modeling approach for the analysis and design of complex systems, focusing on the actors that use the system and decomposing the specification according to their needs. With this prospect, our team developed a UML profile named VUML (View based UML), which allows the elaboration of a unique and sharable model accessible according to the view of each of the system's actors. However the achieved work on the VUML profile does not tackle the behavior aspects of the modeling process. The VUML approach address the structural aspects related to the composition of views and to the sharing of data without dealing with the way these views will react, or how to be able to synchronize them in order to obtain the behavior of multiple-view objects (instances of a multi-view class). The achieved work in this thesis aims to fill this gap by providing new mechanism to the VUML profile that allows expressing the behavioral needs of a system. We will focus on describing the individual behavior of multi-view objects by state-machines that require adjustments of UML modeling concepts. To achieve this objective we introduced the concept of event probes, which allow to specify implicit communication between the view-objects via event observation. This allows decoupling the view specifications that are a priori strongly interconnected, and therefore allows them to be designed separately, in agreement with the VUML method recommendations, and then to be integrated without the need of making modifications. We first define the concept of event monitoring and identified the different types of probes and the appropriate parameters that characterize them. We also define a set of concepts that can extend and manipulate probes. Then we propose a UML-compatible representation of the introduced concepts in form of a profile named VxUML (extension of VUML). In addition to defining the profile elements (stereotypes, tagged value, predefined library classes), we have developed rules for proper formation of the static semantics using OCL to reduce ambiguity in the specification of such concepts. Afterwards, to demonstrate the usefulness of the concepts introduced, we developed a case study through which we sought to provide a full view-based model, addressing both structural and behavioral aspects. At the end, to concretely validate our approach in a model driven engineering setting, we developed a code generator that takes as input a specification developed in VxUML profile. This generator uses the techniques of model transformation related to the code generation, including transformation of platform independent models (PIM) to platform specific models (PSM), and transformation of PSMs to code; the current target language is Java. Finally, another contribution of this thesis is a process associated with VxUML. It is an approach that complements the approach associated with VUML (which deal only with structural aspects) to be able to use in methodical manner the new mechanisms dedicated to behavioral treatment. Now, the VxUML development process offers a complete view based modeling, that is, dealing with both structural and behavioral aspects. Keywords: View based modeling, VUML profile, VxUML profile, event observation, multi-view states machine, behavior composition.La modélisation par points de vue constitue la thématique générale de notre travail de thèse. C'est une approche de modélisation orientée objet, visant l'analyse et la conception des systèmes complexes avec une démarche centrée autour des acteurs interagissant avec le système. Notre équipe a ainsi développé un profil UML appelé VUML (View based UML), qui permet l'élaboration d'un modèle unique partageable à partir de vues associées aux points de vue des acteurs. Cependant, les travaux réalisés sur le profil VUML [Nassar, 05 ; Anwar, 09] ne couvrent pas les aspects comportementaux de la modélisation. En effet, – en proposant la notion de classe multivue – VUML traite les aspects structuraux liés à la composition des vues et au partage des données statiques sans prendre en compte la manière dont ces vues vont réagir, ni comment les synchroniser afin de représenter le comportement des objets multivue (instances d'une classe multivue). Les travaux effectués dans le cadre de cette thèse cherchent à combler ce manque en dotant le profil VUML de nouveaux mécanismes permettant d'exprimer le comportement d'un système. Nous nous sommes concentrés pour cela sur le comportement des objets multivue décrit par des machines à états qui nécessitent des adaptations des concepts de modélisation UML. Pour réaliser cet objectif nous avons introduit la notion de sonde d'événements, qui permet de spécifier des communications implicites entre les vues par observation d'événements. Ceci permet de découpler des spécifications qui sont a priori fortement interconnectées, de les concevoir séparément par points de vue, selon les préconisations de la méthode VUML, puis de les intégrer sans avoir à les modifier. Nous avons tout d'abord défini le concept de sonde d'événements, identifié les différents types de sondes avec les paramètres associés, puis défini un ensemble de concepts permettant d'enrichir et de manipuler les sondes. Nous avons ensuite proposé une représentation compatible avec VUML des concepts introduits sous forme d'un profil nommé VxUML (extension de VUML). En plus de la définition des éléments du profil (stéréotypes, valeurs marquées, classes de librairie prédéfinies), nous avons développé en OCL des règles de bonne formation (sémantique statique). Pour illustrer l'intérêt des concepts introduits, nous avons développé une étude de cas en proposant une modélisation par points de vue complète traitant à la fois les aspects structurel et comportemental. Pour valider concrètement notre approche, nous avons développé, selon une approche IDM, un générateur de code qui prend en entrée une spécification de système en VxUML. Ce générateur utilise les techniques de transformation de modèles liées à la génération de code, et notamment les transformations de modèles indépendants de plate-forme (PIM) vers des modèles spécifiques à une plate-forme (PSM), et des modèles PSM vers le code ; il a été développé dans un premier temps avec le langage cible Java. Sur le plan méthodologique, nous avons défini une démarche associée à VxUML, qui complète celle de VUML, en permettant d'utiliser d'une manière méthodique les mécanismes dédiés au traitement du comportement. Désormais, le processus de développement VxUML permet une modélisation par points de vue complète, traitant à la fois les aspects structurel et comportemental. Mots clés : Conception par points de vue, profil VUML, profil VxUML, sonde d'événements, machine à états multivue, composition du comportement

A Game-Theoretic Approach to Strategic Resource Allocation Mechanisms in Edge and Fog Computing

With the rapid growth of Internet of Things (IoT), cloud-centric application management raises questions related to quality of service for real-time applications. Fog and edge computing (FEC) provide a complement to the cloud by filling the gap between cloud and IoT. Resource management on multiple resources from distributed and administrative FEC nodes is a key challenge to ensure the quality of end-user’s experience. To improve resource utilisation and system performance, researchers have been proposed many fair allocation mechanisms for resource management. Dominant Resource Fairness (DRF), a resource allocation policy for multiple resource types, meets most of the required fair allocation characteristics. However, DRF is suitable for centralised resource allocation without considering the effects (or feedbacks) of large-scale distributed environments like multi-controller software defined networking (SDN). Nash bargaining from micro-economic theory or competitive equilibrium equal incomes (CEEI) are well suited to solving dynamic optimisation problems proposing to ‘proportionately’ share resources among distributed participants. Although CEEI’s decentralised policy guarantees load balancing for performance isolation, they are not faultproof for computation offloading. The thesis aims to propose a hybrid and fair allocation mechanism for rejuvenation of decentralised SDN controller deployment. We apply multi-agent reinforcement learning (MARL) with robustness against adversarial controllers to enable efficient priority scheduling for FEC. Motivated by software cybernetics and homeostasis, weighted DRF is generalised by applying the principles of feedback (positive or/and negative network effects) in reverse game theory (GT) to design hybrid scheduling schemes for joint multi-resource and multitask offloading/forwarding in FEC environments. In the first piece of study, monotonic scheduling for joint offloading at the federated edge is addressed by proposing truthful mechanism (algorithmic) to neutralise harmful negative and positive distributive bargain externalities respectively. The IP-DRF scheme is a MARL approach applying partition form game (PFG) to guarantee second-best Pareto optimality viii | P a g e (SBPO) in allocation of multi-resources from deterministic policy in both population and resource non-monotonicity settings. In the second study, we propose DFog-DRF scheme to address truthful fog scheduling with bottleneck fairness in fault-probable wireless hierarchical networks by applying constrained coalition formation (CCF) games to implement MARL. The multi-objective optimisation problem for fog throughput maximisation is solved via a constraint dimensionality reduction methodology using fairness constraints for efficient gateway and low-level controller’s placement. For evaluation, we develop an agent-based framework to implement fair allocation policies in distributed data centre environments. In empirical results, the deterministic policy of IP-DRF scheme provides SBPO and reduces the average execution and turnaround time by 19% and 11.52% as compared to the Nash bargaining or CEEI deterministic policy for 57,445 cloudlets in population non-monotonic settings. The processing cost of tasks shows significant improvement (6.89% and 9.03% for fixed and variable pricing) for the resource non-monotonic setting - using 38,000 cloudlets. The DFog-DRF scheme when benchmarked against asset fair (MIP) policy shows superior performance (less than 1% in time complexity) for up to 30 FEC nodes. Furthermore, empirical results using 210 mobiles and 420 applications prove the efficacy of our hybrid scheduling scheme for hierarchical clustering considering latency and network usage for throughput maximisation.Abubakar Tafawa Balewa University, Bauchi (Tetfund, Nigeria

a bottom-up approach for model-based software development

Models in software engineering are descriptive structures so that transformations can connect their contents at a semantic level. In model-based software development, algorithmic program code usually exists alongside models - derived from them or with the purpose to amend them. While thus both kinds of notations must be considered by developers, no consistent mapping is given since transformations between models and code are usually unidirectional for code generation. This impedes a continuous integration of both, limits the applicability of models, and prevents error tracking and monitoring at run time with respect to models. In this thesis, the approach of embedded models is introduced. Embedded models define patterns in program code whose elements have formal relations to models and can be executed by reflection at the same time. Model specifications are thus embedded in implementations and can be accessed by bidirectional transformations for design, verification, execution, and monitoring. The thesis focuses on the development of such patterns and their precise description as well as on the connection to other program code surrounding embedded models. Implementations are described for two modeling domains, state machines and process models, including tools for design, verification, execution, monitoring, and design recovery. The approach is evaluated with two case studies, the modeling of a real-world load generator for performance tests and the development of model-based educational graphical scenarios for university teaching. Both case studies show that the approach is valid and fulfills its purpose for a certain class of applications. Focusing on the integration in implementations, embedded models are thus a bottom-up approach for model-based software development

XXIII Congreso Argentino de Ciencias de la Computación - CACIC 2017 : Libro de actas

Trabajos presentados en el XXIII Congreso Argentino de Ciencias de la Computación (CACIC), celebrado en la ciudad de La Plata los días 9 al 13 de octubre de 2017, organizado por la Red de Universidades con Carreras en Informática (RedUNCI) y la Facultad de Informática de la Universidad Nacional de La Plata (UNLP).Red de Universidades con Carreras en Informática (RedUNCI