1. A method to identify resources, comprising: receiving a plan at a first architectural layer in a computing system, the plan indicating a plurality of resources required to support a service, the plan representing the first architectural layer and at least one second architectural layer in the computer system, the plan stored in a memory; identifying one or more eligible resources of a particular type from the plurality of resources indicated by the plan; selecting a resource instance from the one or more eligible resources; updating the plan to indicate the resource instance; and calling the second architectural layer to supply the selected resource instance.