Almost all current P2P applications are built as monolithic systems: they tightly couple application software with an underlying P2P technology. For simple P2P applications like file sharing of instant messaging this does not represent a deficiency. For more general scenarios, e.g., for providing an electronic market place based on P2P technology, flexibility has to be increased. We propose to decouple the application from its underlying P2P network and introduce a mechanism that allows us to dynamically bind an overlay from a given set to a specific application. This paper describes the design of such a systems architecture that combines the service-oriented architecture paradigm and P2P technology. Using these two different technologies in an integrated way gives us flexibility to bind the best fitting P2P network to the executed service. In addition, it allows us to easily add and deploy new services.