This article presents an extension of the Fractal component model targeted at programming applications to be run on computing grids: the Grid Component Model (GCM). First, to address the problem of deployment of components on the Grid, deployment strategies have been de ned. Then, as Grid applications often result from the composition of a lot of parallel (sometimes identical) components, composition mechanisms to support collective communications on a set of components are introduced. Finally, because of the constantly evolving environment and requirements for Grid applications, the GCM de nes a set of features intended to support component autonomicity. All these aspects are developed in this paper with the challenging objective to ease the programming of Grid applications, while allowing GCM components to also be the unit of deployment and management

SUMMARYRecently, there has been a lot of interest in using Java for parallel programming. Efforts have been hindered by lack of standard Java parallel programming APIs. To alleviate this problem, various groups started projects to develop Java message passing systems modelled on the successful Message Passing Interface (MPI). Official MPI bindings are currently defined only for C, Fortran, and C++, so early MPI-like environments for Java have been divergent. This paper relates an effort undertaken by a working group of the Java Grande Forum, seeking a consensus on an MPI-like API, to enhance the viability of parallel programming using Java.

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While there is growing interest in using Java for high-performance applications, many in the highperformance computing community do not believe that Java can match the performance of traditional native message passing environments.This paper discusses critical issues that must be addressed in the design of Java based message passing systems. Efficient handling of these issues allows Java-MPI applications to obtain performance which rivals that of traditional native message passing systems. To illustrate these concepts, the design and performance of a pure Java implementation of MPI are discussed.

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