Application of Micro-Genetic Algorithm for Task Based Computing

Abstract — Pervasive computing calls for applications which are often composed from independent and distributed components using facilities from the environment. This paradigm has evolved into task based computing where the application composition relies on explicit user task descriptions. The composition of applications has to be performed at run-time as the environment is dynamic and heterogeneous due to e.g., mobility of the user. An algorithm that decides on a component set and allocates it onto hosts accordingly to user task preferences and the platform constraints plays a central role in the application composition process. In this paper we will describe an algorithm for task-based application allocation. The algorithm uses micro-genetic approach and is characterized by a very low computational load and good convergence properties. We will compare the performance and the scalability of our algorithm with a straightforward evolutionary algorithm. Besides, we will outline a system for task-based computing where our algorithm is used. I

تحسين توافرية وأداء النظام الموزع بإعادة انتشار مكونات النظام

استخدمت النظم الموزعة كثيراً في الآونة الأخيرة كبديل عن النظم المركزية نظراً لأدائها الأفضل عندما يزداد حجم النظام أو تزيد الحاجة إلى موارد المعالجة. رغم ذلك لازالت تعاني تلك النظم من مشاكل ضعف التوافرية عند حدوث تغيير في البنية التحتية التي تعمل فوقها مما أدى إلى ظهور مفهوم إعادة انتشار مكونات النظام الموزع. في هذا البحث تم تقديم طريقة لأخذ القرار بإعادة الانتشار الأفضل لبعض مكونات النظام الموزع عن طريق المراقبة الذاتية لحالة عقد النظام الموزع بالاستفادة من نظرية الأرتال، من ثم تقديم تقارير عن تلك الحالة إلى المكون المركزي، الذي يقوم حينئذٍ بأخذ قرار إعادة الانتشار إلى العقد المناسبة. Distributed Systems have been use too often recently as an alternative for central systems, due to their better performance when the size of the system or the need to the system resources becomes bigger. On the other hand, distributed systems are still fussing about the availability lack when a change of the infrastructure of the network take a place, which presents the approach of component redeployment in the distributed systems. In this research, we view a method for making decision about best component redeployment in a distributed system via self-monitoring for node status using the Queuing Theory, then handle reports to the central component, which make the choice about redeployment to the suitable node

Towards User-Oriented Application Composition

International audienceThis paper presents an autonomic system for composing ubiquitous applications at run-time. The applications are composed according to the user preferences collected via a physical user interface. This interface allows users to specify preferences by simple actions of touching with their mobile terminals icons in the environment, instead of explicitly selecting resources and dealing with their properties. In this paper, we present a system prototype and an example multimedia application. We also evaluate the performance of the prototype and the allocation algorithm which is used to compose applications

Microservice Transition and its Granularity Problem: A Systematic Mapping Study

Microservices have gained wide recognition and acceptance in software industries as an emerging architectural style for autonomic, scalable, and more reliable computing. The transition to microservices has been highly motivated by the need for better alignment of technical design decisions with improving value potentials of architectures. Despite microservices' popularity, research still lacks disciplined understanding of transition and consensus on the principles and activities underlying "micro-ing" architectures. In this paper, we report on a systematic mapping study that consolidates various views, approaches and activities that commonly assist in the transition to microservices. The study aims to provide a better understanding of the transition; it also contributes a working definition of the transition and technical activities underlying it. We term the transition and technical activities leading to microservice architectures as microservitization. We then shed light on a fundamental problem of microservitization: microservice granularity and reasoning about its adaptation as first-class entities. This study reviews state-of-the-art and -practice related to reasoning about microservice granularity; it reviews modelling approaches, aspects considered, guidelines and processes used to reason about microservice granularity. This study identifies opportunities for future research and development related to reasoning about microservice granularity.Comment: 36 pages including references, 6 figures, and 3 table

SACRE: Supporting contextual requirements' adaptation in modern self-adaptive systems in the presence of uncertainty at runtime

Runtime uncertainty such as unpredictable resource unavailability, changing environmental conditions and user needs, as well as system intrusions or faults represents one of the main current challenges of self-adaptive systems. Moreover, today's systems are increasingly more complex, distributed, decentralized, etc. and therefore have to reason about and cope with more and more unpredictable events. Approaches to deal with such changing requirements in complex today's systems are still missing. This work presents SACRE (Smart Adaptation through Contextual REquirements), our approach leveraging an adaptation feedback loop to detect self-adaptive systems' contextual requirements affected by uncertainty and to integrate machine learning techniques to determine the best operationalization of context based on sensed data at runtime. SACRE is a step forward of our former approach ACon which focus had been on adapting the context in contextual requirements, as well as their basic implementation. SACRE primarily focuses on architectural decisions, addressing self-adaptive systems' engineering challenges. Furthering the work on ACon, in this paper, we perform an evaluation of the entire approach in different uncertainty scenarios in real-time in the extremely demanding domain of smart vehicles. The real-time evaluation is conducted in a simulated environment in which the smart vehicle is implemented through software components. The evaluation results provide empirical evidence about the applicability of SACRE in real and complex software system domains.Comment: 45 pages, journal article, 14 figures, 9 tables, CC-BY-NC-ND 4.0 licens

SACRE: Supporting contextual requirements’ adaptation in modern self-adaptive systems in the presence of uncertainty at runtime

Runtime uncertainty such as unpredictable resource unavailability, changing environmental conditions and user needs, as well as system intrusions or faults represents one of the main current challenges of self-adaptive systems. Moreover, today’s systems are increasingly more complex, distributed, decentralized, etc. and therefore have to reason about and cope with more and more unpredictable events. Approaches to deal with such changing requirements in complex today’s systems are still missing. This work presents SACRE (Smart Adaptation through Contextual REquirements), our approach leveraging an adaptation feedback loop to detect self-adaptive systems’ contextual requirements affected by uncertainty and to integrate machine learning techniques to determine the best operationalization of context based on sensed data at runtime. SACRE is a step forward of our former approach ACon which focus had been on adapting the context in contextual requirements, as well as their basic implementation. SACRE primarily focuses on architectural decisions, addressing selfadaptive systems’ engineering challenges. Furthering the work on ACon, in this paper, we perform an evaluation of the entire approach in different uncertainty scenarios in real-time in the extremely demanding domain of smart vehicles. The real-time evaluation is conducted in a simulated environment in which the smart vehicle is implemented through software components. The evaluation results provide empirical evidence about the applicability of SACRE in real and complex software system domains.Peer ReviewedPostprint (author's final draft

A Decentralized Redeployment Algorithm for Improving the Availability of Distributed Systems

In distributed and mobile environments, the connections among the hosts on which a software system is running are often unstable. As a result of connectivity losses, the overall availability of the system decreases. The distribution of software components onto hardware nodes (i.e., the system’s deployment architecture) may be ill-suited for the given target hardware environment and may need to be altered to improve the software system’s availability. Determining a software system’s deployment that will maximize its availability is an exponentially complex problem. Although several polynomial-time approximative techniques have been developed recently, these techniques rely on the assumption that the system’s deployment architecture and its properties are accessible from a central location. For these reasons, the existing techniques are not applicable to an emerging class of decentralized systems marked by the limited system wide knowledge and lack of centralized control. In this paper we present an approximative solution for the redeployment problem that is suitable for decentralized systems and asses its performance

A Decentralized Redeployment Algorithm for Improving the Availability of Distributed Systems

Abstract. In distributed and mobile environments, the connections among the hosts on which a software system is running are often unstable. As a result of connectivity losses, the overall availability of the system decreases. The distribution of software components onto hardware nodes (i.e., the system’s deployment architecture) may be ill-suited for the given target hardware environment and may need to be altered to improve the software system’s availability. Determining a software system’s deployment that will maximize its availability is an exponentially complex problem. Although several polynomial-time approximative techniques have been developed recently, these techniques rely on the assumption that the system’s deployment architecture and its properties are accessible from a central location. For these reasons, the existing techniques are not applicable to an emerging class of decentralized systems marked by the limited system wide knowledge and lack of centralized control. In this paper we present an approximative solution for the redeployment problem that is suitable for decentralized systems and assess its performance.

Erweiterung einer Komponentenplattform zur Unterstützung multimodaler Anwendungen mit föderierten Endgeräten

Zur Erledigung einer Aufgabe kann der Benutzer mit verschiedenen Endgeräten interagieren, welche unterschiedliche Interaktionsarten (Modalitäten) anbieten. Dabei gibt es jedoch kein Endgerät, welches alle erdenkbaren Modalitäten unterstützt. Aus diesem Grund wird eine komponentenbasierte Integrationsschicht auf Basis einer Komponentenplattform entwickelt, die dem Nutzer die gewünschte Freiheit bei der Wahl der Endgeräte und somit der Modalitäten ermöglicht. Als Ausgangsbasis dafür dient das W3C Multimodal Interaction Framework. Mit Hilfe der Integrationsschicht kann der Nutzer beispielsweise Endgeräteföderationen erzeugen, die einzeln oder gemeinsam zur Interaktion verwendet werden können. Die Integrationsschicht besitzt verschiedene Konzepte, um z.B. Geschäftslogik zur Laufzeit zu verteilen, Komponentenausfälle zu behandeln und die auf verschiedene Endgeräte verteilte Nutzerschnittstelle zu synchronisieren. Die entwickelten Konzepte wurden prototypisch implementiert, validiert und auf Performanz untersucht