The high computational demand and the modularity of future space applications make the effort of developing multithreading reusable middlewares worthwhile. In this paper, we present a multihreading execution platform and a Software development framework that consists of abstract classes with virtual methods. The presented work is written in C++ following the event-driven programming paradigm and based on the inverse of control programming principle. The platform is portable over different operating systems, e.g., Linux and RTEMS. This platform is supported with a modeling language to automatically generate the code from the given requirements. Our platform has been used in already flying satellites, e.g., Eu:CROPIS. We present in this paper an example that illustrates how to use the proposed platform in designing and implementing an on-board software system.