Configurable business software solutions are increasingly being implemented based on service oriented architectures (SOA). Hereunto model driven approaches for the definition and implementation of such software systems are indispensable. In addition reference models with pre-defined business processes can accelerate decisively the implementation of standard software solutions. In this paper we present a new integrated service oriented approach of a multi-layer model. XML nets, a kind of high-level Petri nets based on XML standards and Web Service nets that are additionally based on web service standards provide the creation of reference models for configurable business software solutions and can be used for the implementation. The reference models are structured in layers of different kind of granularity. Within these layers complex processes can be orchestrated using business process components. The business flows within the capsulated processes are defined with Web Service nets consi...