“This talk will focus on challenges in designing software libraries and middleware for upcoming exascale systems with millions of processors and accelerators. Two kinds of application domains – Scientific Computing and Big data will be considered. For scientific computing domain, we will discuss about challenges in designing runtime environments for MPI and PGAS (UPC and OpenSHMEM) programming models by taking into account support for multi-core, high-performance networks, GPGPUs and Intel MIC. “