Abstract. Grids raise new challenges in the following way: heterogeneity of underlying machines/networks and runtime environments (types and performance characteristics), not a single administrative domain, versatility. So the need to have appropriate programming and runtime solutions in order to write, deploy then execute applications on such heterogeneous distributed hardware in an effective and efficient manner. We propose in this article a solution to those challenges which takes the form of a programming and deployment framework featuring parallel, mobile, secure and distributed objects and components.

Group communication is a crucial feature for high-performance and Grid computing. While previous works and libraries proposed such a characteristic (e.g. MPI, or object-oriented frameworks), the use of groups imposed specific constraints on programmers -for instance the use of dedicated interfaces to trigger group communications.We aim at a more flexible mechanism. More specifically, this paper proposes a scheme where, given a Java class, one can initiate group communications using the standard public methods of the class together with the classical dot notation; in that way, group communications remains typed. Furthermore, groups are automatically constructed to handle the result of collective operations, providing an elegant and effective way to program gather operations. This flexibility also allows to handle results that are groups of remotely accessible objects, and to use a group as a means to dispatch different parameters to different group members (for instance in a cyclic manner). Furthemore, hierarchical groups can be easily and dynamically constructed; an important feature to achieve the use of several clusters in Grid computing.Performance measures demonstrate the viability of the approach. The challenge is to provide easy to use, efficient, and dynamic group management for objects dynamically distributed on the Grid.

This article presents an evolution of classical SPMD programming for clusters and grids.It is named "Object-Oriented SPMD" as it is based on remote method invocation. More precisely, it is based on an active object pattern, extended as a typed group of active objects, to which SPMID's specificities are added. The proposed programming model is more flexible: techniques to postpone barrier and to remove any explicit loop make it possible to privilege reactivity and reuse.The resulting OO-SPMD API has been implemented in ProActive. Good scalability and quite competitive performances, compared to what is obtained using C-MPI, are demonstrated.