André Ribes

A Parallel Corba Component Model for Numerical Code Coupling

The fast growth of high bandwidth wide area networks has allowed the building of computational grids, which are constituted of PC clusters and/or parallel machines. Computational grids enable the design of new numerical simulation applications. For example, it is now feasible to couple several scientific codes to obtain a multi-physic application. In order to handle the complexity of such aplications, software component technology appears very appealing. However, most current software component models do not provide any support to transparently and efficiently embed parallel codes into components. This paper deals with GridCCM, an extension to the CORBA (Common Object Request Broker Architecture) Component Model to support parallel components. The feasibility of the model is evaluated thanks to its implementation on top of two CCM prototypes. Preliminary performance results are very good; there is no significant overhead while aggregating the network bandwidth capability of a parallel component.

PACO++: a parallel object model for high performance distributed systems

The availability of high bandwidth wide area networks enables the coupling of several computing resources - supercomputers or PC clusters - together to obtain a high performance distributed system. The question is to determine a suitable programming model that provides transparency, interoperability, reliability, scalability and performance. Since such systems appear as a combination of distributed and parallel systems, it is tempting to extend programming models that were associated to distributed or to parallel systems. Another choice is to combine the two different worlds into a single coherent one. A parallelism oriented model appears more adequate to program parallel codes while a distributed oriented model is more suitable to handle inter-code communications. This issue is addressed with the concept of parallel object. We have applied it to Corba so as to define a parallel Corba object: it is a collection of identical Corba objects with a single program multiple data (SPMD) execution model. This paper presents PACO++, a portable implementation of the concept of parallel Corba object. It examines how the different design issues have been tackled with. For example, scalability is achieved between two parallel Corba objects by involving all members of both collections in the communication: an aggregated bandwidth of 874 Mbit/s has been obtained on a 1 Gbit/s WAN. Such a performance is obtained while preserving the semantics of Corba and in particular interoperability with standard Corba objects.

A Parallel CORBA Component Model for Numerical Code Coupling

The fast growth of high bandwidth wide area networks has allowed the building of computational grids, which are constituted of PC clusters and/or parallel machines. Computational grids enable the design of new numerical simulation applications. For example, it is now feasible to couple several scientific codes to obtain a multi-physic application. In order to handle the complexity of such applications, software component technology appears very appealing. However, most current software component models provide no support to transparently and efficiently embed parallel codes into components. This paper describes a first study of GridCCM, an extension to the CORBA Component Model to support parallel components. The feasibility of the model is evaluated thanks to its implementation on top of two CCM prototypes. Preliminary performance results show that bandwidth is efficiently aggregated.

Padico: a component-based software infrastructure for Grid computing

This paper describes work in progress to develop a component-based software infrastructure, called Padico, for computational Grids based on the CORBA Component Model from the OMG. The objective of Padico is to offer a component model targeting multi-physics simulations or any applications that require the coupling of several codes (simulation or visualization) within a high-performance environment. This paper addresses mainly two issues we identified as important for a Grid-aware component model. The first issue deals with the encapsulation of parallel codes into components. We propose an extension to the CORBA Component Model called GridCCM. The second issue addresses the problem of the communication between components within a computational Grid. We propose a portable runtime, called Padico/spl trade/, able to efficiently support communication in a heterogeneous networking environment.

Handling Exceptions Between Parallel Objects

Scientific computing is evolving from parallel processing to distributed computing with the availability of new computing infras- tructures such as computational grids. We investigate the design of a component model for the Grid aiming at combining both parallel and distributed processing in a seamless way. Our approach is to extend com- ponent models with the concept of parallel components. At runtime, most component models rely on a distributed object model. In this paper, we study an exception handling mechanism suitable for dealing with parallel entities, such as parallel objects, that appear as collections of identical objects but acting as a single object from the programmers viewpoint.

On the design of Adaptive Mesh Refinement applications based on software components

Designing Adaptive Mesh Refinement based applications is a very complex task. The aim of this paper is to study whether component models could simplify their conception and which concepts are needed. The analysis is based on an implementation of an AMR method on top of two component models, ULCM and SALOME.