Visual Programming of Fault-Tolerant Distributed Applications

The design of fault-tolerant distributed applications is a complex task. In addition to application functionalities, the programmer must consider issues related to both replication and distribution for every application component concerned with fault-tolerance. This paper describes an approach which combines two environments (SystemSpecs and GARF) so as to: (1) graphically design applications using high level Petri nets and (2) discharge the programmer of faulttolerance issues. 1 Introduction The design of fault-tolerant distributed applications is a complex task. Considering replication and distribution at design time complicates the programmer's work and may distract him from his main task: implementing application functionalities. Moreover, making a component fault-tolerant is independent of its functionality and may be automatically performed. This paper presents the integration of two environments: GARF [1, 2] and SystemSpecs [3] in order to automatically build fault-tolerant ap..

Édition Coopérative et Large Échelle dans Duplex

{\DUPLEX} est un environnement d'édition coopérative pour des utilisateurs connectés sur Internet. La large échelle implique l'hétérogénéité, des délais de communication non bornés et des pannes. Dans ce cadre, les techniques traditionnelles utilisées pour l'édition coopérative dans un réseau local sont inefficaces. {\DUPLEX} propose un modèle basé sur une décomposition du document en parties indépendantes maintenues individuellement par un noyau dupliqué. Le traitement de l'atomicité et du contrôle de duplication devient réalisable puisque confiné à un petit contexte. Les utilisateurs interagissent avec le noyau soit en récupérant une copie locale d'un objet du noyau qu'ils peuvent modifier à loisir dans leur environnement local, soit au contraire en répercutant au niveau du noyau une copie locale. Les communications sont réduites au minimun autorisant une utilisation à large échelle. Le contrôle de concurrence offre des mécanismes optimistes ou pessimistes pour chaque objet individuellement tout en garantissant une cohérence forte (la linéarisabilité)

Visual Programming of Fault-Tolerant Distributed Applications

The design of fault-tolerant distributed applications is a complex task. In addition to application functionalities, the programmer must consider issues related to both replication and distribution for every application component concerned with fault-tolerance. This paper describes an approach which combines two environments (Specs and Garf) so as to: (1) graphically design applications using high level Petri nets and (2) discharge the programmer of fault-tolerance issues

Customizing the behavior of middleware: the PIE approach

New York, US

Integration of cell-free expression and solid-state NMR to investigate the dynamic properties of different sites of the growth hormone secretagogue receptor

Cell-free expression represents an attractive method to produce large quantities of selectively labeled protein for NMR applications. Here, cell-free expression was used to label specific regions of the growth hormone secretagogue receptor (GHSR) with NMR-active isotopes. The GHSR is a member of the class A family of G protein-coupled receptors. A cell-free expression system was established to produce the GHSR in the precipitated form. The solubilized receptor was refolded in vitro and reconstituted into DMPC lipid membranes. Methionines, arginines, and histidines were chosen for 13C-labeling as they are representative for the transmembrane domains, the loops and flanking regions of the transmembrane α-helices, and the C-terminus of the receptor, respectively. The dynamics of the isotopically labeled residues was characterized by solid-state NMR measuring motionally averaged 1H-13C dipolar couplings, which were converted into molecular order parameters. Separated local field DIPSHIFT experiments under magic-angle spinning conditions using either varying cross polarization contact times or direct excitation provided order parameters for these residues showing that the C-terminus was the segment with the highest motional amplitude. The loop regions and helix ends as well as the transmembrane regions of the GHSR represent relatively rigid segments in the overall very flexible receptor molecule. Although no site resolution could be achieved in the experiments, the previously reported highly dynamic character of the receptor concluded from uniformly 13C labeled receptor samples could be further specified by this segmental labeling approach, leading to a more diversified understanding. of the receptor dynamics under equilibrium condition