Sylvain Reynaud

A XML-based description language and execution environment for orchestrating grid jobs

Grids are often used through simplified job submission interfaces that abstract the underlying grid infrastructure as a black box. These interfaces suit well to developers of simple grid applications requiring the coordination of grid jobs, for which monitoring and error handling are done more or less manually. However, developers of advanced grid applications such as grid portals need more flexible tools to develop efficient and robust applications with advanced capabilities such as monitoring, error handling, failure recovery, resource release, etc. In this paper, we present through a typical application example a XML-based language designed to describe applications orchestrating grid jobs. We also present the execution environment supporting the proposed language and we show how even simple grid applications can be expressed in this language and benefit of the advanced capabilities of the execution environment.

Uniform Access to Heterogeneous Grid Infrastructures with JSAGA

Grids have been developed to provide uniform access to computing and storage resources, but since existing grid infrastructures have been deployed within the context of distinct projects, technological choices have often differed. Many users need to use several grid infrastructures, and they are facing complexity because of these differences.

From EGEE Operations Portal towards EGI Operations Portal

EGEE to EGI structure based on NGIs evolution induces a large move from the operations that will rely on a sustainable and largely decentralized model. One of the key evolutions for the challenge in the regionalisation relies in the scalability and the flexibility required regarding information source types and information handling. For 5 years, we have developed and maintained a standard-based component that allows us to address both theses issues. This open-source tool, named Lavoisier, has been a critical success factor for the operations dashboard, one of the Operations Portal main features. Indeed, it enables coherent efficient and reliable data handling which is customizable and scalable, as Lavoisier is an extensible service designed to provide a unified view of data collected from multiple heterogeneous data sources. Data views are represented and accessed as XML documents through standard languages such as XSLT, XPath. Moreover, scalability and reliability are enforced by a caching mechanism adaptable to specific data sources and use-cases. We will namely expose how the concept and the implementation enable clear roles separation between plug-in developer, service configuration administrator or end-user. Also, maintainability of the portal code has increased dramatically as the latter is now independent from the data sources technology or from the cache management policies. Finally, integration of data has recently been simplified as the service administrator proceeds now through web interfaces

Le risque d'éboulement des ruines de Séchilienne Étude des modalités de rupture du barrage naturel sur modèle physique

Le versant du mont Sec au lieu dit des ”ruines de Sechilienne” est instable. Des blocs sont susceptibles de tomber. C’est pourquoi de nombreux capteurs surveillent en continu les deplacements de ce versant de montagne. Les experts estiment aujourd’hui qu’il est possible qu’un volume total de l’ordre de trois millions de metres cubes de materiaux s’eboulent dans les trente a cinquante prochaines annees. Dans le pire des cas, il est possible qu’un barrage naturel barre la vallee et donc le cours de la Romanche, d’une hauteur de l’ordre de 6m. Que se passerait-il en cas de crue de la Romanche ? Si le barrage naturel se rompait brusquement, une onde de crue se propagerait rapidement dans la vallee. Pour prevenir ce scenario catastrophe, les premieres etudes de faisabilite prevoyaient la construction de « parades hydrauliques » constituees de casiers et de digues, pour un montant de travaux de plusieurs millions d’Euros. La determination du debit sortant du barrage naturel est un enjeu majeur pour le choix des parades hydrauliques a adopter. Devant la complexite du phenomene de rupture du barrage naturel, les modelisations mathematiques necessitent de prendre beaucoup trop d’hypotheses pour obtenir un resultat fiable. Seule une modelisation sur un modele reduit physique permet de lever ces incertitudes. C’est pourquoi le Sy ndicat M ixte des B assins H ydrauliques de l’ I sere (Symbhi 38) a decide de confier une etude sur modele physique a la CNR. Le modele respecte les regles classiques de similitude de Froude et de transport solide. Trente essais ont ete realises pour encadrer tous les scenarios possibles et ont permis de parametrer une loi d’erosion du barrage naturel.