The Isis project: Fault-tolerance in large distributed systems

This final status report covers activities of the Isis project during the first half of 1992. During the report period, the Isis effort has achieved a major milestone in its effort to redesign and reimplement the Isis system using Mach and Chorus as target operating system environments. In addition, we completed a number of publications that address issues raised in our prior work; some of these have recently appeared in print, while others are now being considered for publication in a variety of journals and conferences

Eventual Consistency: Origin and Support

Eventual consistency is demanded nowadays in geo-replicated services that need to be highly scalable and available. According to the CAP constraints, when network partitions may arise, a distributed service should choose between being strongly consistent or being highly available. Since scalable services should be available, a relaxed consistency (while the network is partitioned) is the preferred choice. Eventual consistency is not a common data-centric consistency model, but only a state convergence condition to be added to a relaxed consistency model. There are still several aspects of eventual consistency that have not been analysed in depth in previous works: 1. which are the oldest replication proposals providing eventual consistency, 2. which replica consistency models provide the best basis for building eventually consistent services, 3. which mechanisms should be considered for implementing an eventually consistent service, and 4. which are the best combinations of those mechanisms for achieving different concrete goals. This paper provides some notes on these important topics

Despliegue del servicio RoutingMaps en entornos "cloud"

[ES] El proceso de despliegue de servicios en entornos cloud es complejo, pues se deben gestionar problemas como las posibles interrupciones del servicio, la pérdida de calidad del servicio en determinadas situaciones, la compatibilidad entre versiones de componentes o la gestión del estado del servicio. En este trabajo académico se analizan los distintos problemas del proceso de despliegue y se diseña e implementa una solución para cada uno de ellos. Las soluciones obtenidas se aplicarán en el proceso de migración de la aplicación de escritorio de gestión de enrutamiento de vehículos, RoutingMaps, a un servicio desplegado en entornos cloud. En este proceso de migración se diseña e implementa una arquitectura basada en microservicios. Todos los componentes del servicio se ejecutarán en contenedores Docker y serán gestionados por el orquestador de contenedores Kubernetes.[EN] The process of deploying services in cloud environments is complex, problems such as possible service interruptions, loss of quality of service in certain situations, compatibility between versions of components or management of service state must be managed. In this academic work the different problems of the deployment process are analyzed and a solution for each one of them is designed and implemented. The solutions obtained will be applied in the process of migrating the vehicle routing management desktop application, RoutingMaps, to a service deployed in cloud environments. In this migration process, a microservices-based architecture is designed and implemented. All components of the service will run in Docker containers and will be managed by the Kubernetes container orchestrator.Morant Moya, Ó. (2020). Despliegue del servicio RoutingMaps en entornos "cloud". http://hdl.handle.net/10251/151173TFG

Soluciones distribuidas para una aplicación cliente/servidor de simulación

En el documento se describen tres diferentes modelos de distribución de una aplicación cliente/servidor centralizada, con el fin de reducir los retrasos en los mensajes, aportar escalabilidad y aportar tolerancia a fallos, con sus respectivas simulaciones y estudios de los datos obtenidos.Villar Monserrat, A. (2008). Soluciones distribuidas para una aplicación cliente/servidor de simulación. http://hdl.handle.net/10251/13618Archivo delegad

Déploiement d'applications patrimoniales en environnements de type informatique dans le nuage

L'objectif de cette thèse est d'offrir une solution de bout en bout permettant de décrire et de déployer de façon fiable une application distribuée dans un environnement virtualisé. Ceci passe par la définition d'un formalisme permettant de décrirer une application ainsi que son environnement d'exécution, puis de fournir les outils capable d'interpéter ce formalisme pour déployer (installer, instancier et configurer) l'application sur une plate-forme de type cloud computing.Cloud computing aims to cut down on the outlay and operational expenses involved in setting up and running applications. To do this, an application is split into a set of virtualized hardware and software resources. This virtualized application can be autonomously managed, making it responsive to the dynamic changes affecting its running environment. This is referred to as Application Life-cycle Management (ALM). In cloud computing, ALM is a growing but immature market, with many offers claiming to significantly improve productivity. However, all these solutions are faced with a major restriction: the duality between the level of autonomy they offer and the type of applications they can handle. To address this, this thesis focuses on managing the initial deployment of an application to demonstrate that the duality is artificial. The main contributions of this work are presented in a platform named VAMP (Virtual Applications Management Platform). VAMP can deploy any legacy application distributed in the cloud, in an autonomous, generic and reliable way. It consists of: a component-based model to describe the elements making up an application and their projection on the running infrastructure, as well as the dependencies binding them in the applicative architecture; an asynchronous, distributed and reliable protocol for self-configuration and self-activation of the application; mechanisms ensuring the reliability of the VAMP system itself. Beyond implementing the solution, the most critical aspects of running VAMP have been formally verified using model checking tools. A validation step was also used to demonstrate the genericity of the proposal through various real-life implementations.SAVOIE-SCD - Bib.électronique (730659901) / SudocGRENOBLE1/INP-Bib.électronique (384210012) / SudocGRENOBLE2/3-Bib.électronique (384219901) / SudocSudocFranceF

Optimal Primary-Backup Protocols

. We give primary--backup protocols for various models of failure. These protocols are optimal with respect to degree of replication, failover time, and response time to client requests. 1 Introduction One way to implement a fault-tolerant service is to employ multiple sites that fail independently. The state of the service is replicated and distributed among these sites, and updates are coordinated so that even when a subset of the sites fail, the service remains available. A common approach to structuring such replicated services is to designate one site as the primary and all the others as backups. Clients make requests by sending messages only to the primary. If the primary fails, then a failover occurs and one of the backups takes over. This service architecture is commonly called the primary-backup or the primary-copy approach [1]. In [5] we give lower bounds for implementingprimary-backup protocols under various models of failure. These lower bounds constrain the degree of..