CloudHealth: A Model-Driven Approach to Watch the Health of Cloud Services

Cloud systems are complex and large systems where services provided by different operators must coexist and eventually cooperate. In such a complex environment, controlling the health of both the whole environment and the individual services is extremely important to timely and effectively react to misbehaviours, unexpected events, and failures. Although there are solutions to monitor cloud systems at different granularity levels, how to relate the many KPIs that can be collected about the health of the system and how health information can be properly reported to operators are open questions. This paper reports the early results we achieved in the challenge of monitoring the health of cloud systems. In particular we present CloudHealth, a model-based health monitoring approach that can be used by operators to watch specific quality attributes. The CloudHealth Monitoring Model describes how to operationalize high level monitoring goals by dividing them into subgoals, deriving metrics for the subgoals, and using probes to collect the metrics. We use the CloudHealth Monitoring Model to control the probes that must be deployed on the target system, the KPIs that are dynamically collected, and the visualization of the data in dashboards.Comment: 8 pages, 2 figures, 1 tabl

Architecture dynamique basée sur la description de la variabilité et des services identifiés depuis des applications orientées objet

Service Oriented Architecture (SOA) is an architectural design paradigm which facilitates building and composing flexible, extensible and reusable service-oriented assets. These latter are encapsulated behind well-defined and published interfaces that can be dynamically discovered by third-party services. Before the advent of SOA, several software systems were developed using older technologies. Many of these systems still afford a business value, however they suffer from evolution and maintenance problems. It is advantageous to modernize those software systems towards service-based ones. In this sense, several re-engineering techniques propose migrating object-oriented applications towards SOA. Nonetheless, these approaches rely on ad-hoc criteria to correctly identify services in object-oriented legacy source code.Besides, one of the most distinguishing features of a service-oriented application is the ability to dynamically reconfigure and adjust its behavior to cope with changing environment during execution. However, in existing architecture description languages handling this aspect, reconfiguration rules are represented in an ad-hoc manner; reconfiguration scenarios are often implicit. This fact hinders a full management of dynamic reconfiguration at architecture level. Moreover, it constitutes a challenge to trace dynamic reconfiguration description/management at different levels of abstraction.In order to overcome the aforementioned problems, our contributions are presented in two axes: First, in the context of migrating legacy software towards SOA, we propose a service identification approach based on a quality measurement model, where service characteristics are considered, refined to measurable metrics in order to measure the semantic correctness of identified services. The second axis is dedicated to an Architecture Description Language (ADL) proposition that describes a variant-rich service-based architecture. In this modular ADL, dynamic reconfigurations are specified at architecture level. Moreover, the description is enriched with context and variability information, in order to enable a variability-based self-reconfiguration of architecture in response to context changes at runtime.L'Orienté Service (SOA) est un paradigme de conception qui facilite la construction d’applications extensibles et reconfigurables basées sur des artefacts réutilisables qui sont les services. Ceux-ci sont structurés via des interfaces bien définies et publiables et qui peuvent être dynamiquement découvertes.Beaucoup d’approches ont été proposées dans la littérature pour la réingénierie d’applications existantes développées dans des paradigmes pré-services, principalement l’orienté objet, vers SOA. L’objectif est de permettre de sauvegarder la valeur métier de ces d’applications tout en leur permettant de bénéficier des avantages de SOA. Le problème est que ces approches s'appuient sur des critères ad-hoc pour identifier correctement des services dans le code source des applications existantes.Par ailleurs, l'une des caractéristiques les plus distinctives d'une application orientée service est sa capacité de se reconfigurer dynamiquement et d'adapter son comportement en fonction de son contexte d'exécution. Cependant, dans les langages de description d'architecture (ADL) existants dont l’aspect de reconfiguration et pris en compte, les règles de reconfiguration sont représentées d'une manière ad-hoc; en général, elles ne sont pas modélisées d'une manière explicite mais enfouillées dans la description de l'architecture. D'une part, ceci engendre une difficulté de la gestion de la reconfiguration dynamique au niveau de l'architecture et d’autre part, la traçabilité de la description de la reconfiguration dynamique à travers les différents niveaux d'abstraction est difficile à représenter et à gérer.Afin de surmonter les problèmes précédents, nous proposons dans le cadre de cette thèse deux contributions. D'abord, nous proposons une approche d'identification de services basée sur un modèle de qualité où les caractéristiques des services sont étudiées, raffinées et réifiées en une fonction que nous utilisons pour mesurer la validité sémantique de ces services. La deuxième contribution consiste en une proposition d'un langage de description d'architecture orientée service (ADL) qui intègre la description de la variabilité architecturale. Dans cette ADL les services qui peuvent constituer l’architecture, les éléments de contexte dont les changements d’état sont à l’origine des changements architecturaux, les variantes des éléments architecturaux sélectionnées en fonction des états des éléments de contexte et le comportement architectural dynamique sont ainsi spécifiés de façon modulaire

An Architecture Description Language for Dynamic Service-Oriented Product Lines

International audienceReconciling Software Product Lines (SPL) and Service Oriented Architecture (SOA) allows modeling and implementing systems that systematically adapt their behavior in respond to surrounding context changes. Both approaches are complementary with regard to the variability and the dynamicity properties. Architecture Description Language (ADL), on the other hand, is recognized as an important element in the description and analysis of software properties. Different ADLs have been proposed in SOA or in SPL domains. Nevertheless, none of these ADLs allows describing variability and dynamicity features together in the context of service-oriented dynamic product lines. In this sense, our work attempts to describe the changing architecture of Dynamic Service-Oriented Product Lines (DSOPL). We propose an ADL that allows describing three types of information: architecture's structural elements, variability elements and system’s configuration. Furthermore, we introduce context elements on which service reconfiguration is based

Reconfigurable Service-Based Architecture Based on Variability Description

International audienceSelf-adaptive systems evolve during system's execution against changes in operating environment. Such evolution and re-configuration can be specified at architecture level using a syntactical expressive language such as Architecture Description Languages (ADLs). Variability modeling is an excellent instrument to model variations of software artifacts and their behavior within a self-adaptive system. However , existing ADLs that support dynamic reconfiguration do not explicitly model variation points on which the recon-figuration is based. This constitutes a barrier for a flexible management of reconfiguration at architecture level as well as traceability issues between a dynamic description given at architectural level and its counterpart at other abstraction levels. In this paper, we propose a variant-rich service-oriented ADL that enables system to reconfigure itself at runtime in response to a context change. To this end, our modular ADL, called Dynamic Service-Oriented Product Lines Architecture Description Language (DSOPL-ADL), specifies dynamic reconfigurations at architecture level besides specifying structural, variability and context information. Among several specified variable configurations at architecture level, one concrete configuration is generated at runtime triggered by a context value. Furthermore, an implementation code can be automatically generated from the architectural description

Service Identification Based on Quality Metrics Object - Oriented Legacy System Migration Towards SOA

International audienceMigrating towards Service Oriented Architecture SOA has become a major topic of interest during the recent years. Since emerging service technologies have forced non-service based software systems to become legacy, many efforts and researches have been carried out to enable these legacy systems to survive. In this context, several service identification solutions have been proposed. These approaches are either manual, thus considered expensive, or rely on ad-hoc criteria that fail to identify relevant services. In this paper, within the big picture of migrating object-oriented legacy systems towards SOA, we address automatic service identification from source code based on service quality characteristics. To achieve this, we propose a quality measurement model where characteristics of services are refined to measurable metrics