After 10 years of preparation, the world has entered the Exascale era. These supercomputers confirm the trend of a shift towards accelerated architectures where GPUs provide the computing power. The Alice Recoque Exascale machine to be installed in France, at CEA/TGCC, can only follow this trend. This raises a challenge for French and European applications that have to be redesigned to use these infrastructure.

CExA will work to offer applications a sustainable middleware that can act as a future-proof software catalyst to leverage heterogeneous and GPU-based supercomputers:

1. adopt and adapt Kokkos and contribute to its ecosystem to offer applications a sustainable software catalyst,
2. implement this approach in three demonstrator applications to guide our choices and demonstrate their effectiveness,
3. offer training and contribute to the dissemination of CExA to build an expert network sharing experience and knowledge.

With this project, the CEA will acquire mastery of an essential link in the software stack by increasing its skills on existing tools while filling gaps on critical points for the specific needs of the CEA, the French and European HPC ecosystem.