Systems and methods to enforce policy in a multi-computer service application are described. In one aspect, a scale-independent logical model of an application is generated. The application is for implementation in a distributed computing system. The scale-independent logical model includes multiple components representing logical functions of the application and intercommunication protocols. The model components are converted into one or more instances representative of physical resources used to implement the logical functions. The instances specify information such as communication ports on the physical resources and communication paths that link the physical resources.