Service-oriented applications facilitate the exchange of business services among participants. Existing modeling approaches either apply at a lower of abstraction than required for such applications or fail to accommodate the autonomous and heterogeneous nature of the participants. We present a business-level conceptual model that addresses the above shortcomings. The model gives primacy to the participants in a service-oriented application. A key feature of the model is that it cleanly decouples the specification of an application’s architecture from the specification of individual participants. We formalize the connection between the two—the reasoning that would help a participant decide if a specific application is suitable for his needs. We implement the reasoning in datalog and apply it to a case study involving car insurance.