A novel micro-kernel approach to building parallel/distributed simulation systems is presented. Using this approach, a unified system architecture is developed for incorporating multiple types of simulation processes. The processes hold potential to employ a variety of synchronization mechanisms, and could even alter their choice of mechanism dynamically. Supported mechanisms include traditional lookahead-based conservative and state saving-based optimistic execution approaches. Also supported are newer mechanisms such as reverse computation-based optimistic execution and aggregation-based event processing, all within a single parsimonious application programming interface. The internal implementation and a preliminary performance evaluation of this interface are presented in ?sik, which is an efficient parallel/distributed realization of the micro-kernel architecture in C++.