By means of a systemic approach toward analysis and design of complex systems, we introduce the issue of implementing open computational systems on service-oriented architectures. We start by studying general systems theory, as it accounts for analysis and modeling of complex systems, and then compare three different implementation strategies toward system implementation. As such, the comparison is grounded in the notion of supporting architectures and, more specifically, in the practical case of a service-oriented layered architecture for communicating entities (SOLACE).