Dynamic replacement of software in hard real-time systems: practical assessment

There are systems that cannot be stopped without losses. However, these systems require modifications during their operational life. Dynamic software replacement is a mechanism that allows components updating without stopping the whole system. The paper deals with dynamic replacement in hard real time systems. A protocol for dynamic replacement of software components in embedded hard real time systems was described and proved theoretically. In order to assess it practically, an implementation of the most critical aspects of this protocol has been carried out. Special attention has been devoted to ensure that the protocol does not interfere with the fulfillment of the deadlines of the real time processes and that the schedulability test can be applied