  One way to access the aggregated power of a collection of heterogeneous
machines is to use a grid middleware, such as DIET, GridSolve or NINF. It
addresses the problem of monitoring the resources, of handling the submissions
of jobs and as an example the inherent transfer of input and output data, in
place of the user.
  In this paper we present how to run cosmological simulations using the RAMSES
application along with the DIET middleware. We will describe how to write the
corresponding DIET client and server. The remainder of the paper is organized
as follows: Section 2 presents the DIET middleware. Section 3 describes the
RAMSES cosmological software and simulations, and how to interface it with
DIET. We show how to write a client and a server in Section 4. Finally, Section
5 presents the experiments realized on Grid'5000, the French Research Grid, and
we conclude in Section 6.
