A VDU is an ONAP resource that represents a unit of infrastructure allocation. It expresses the following ideas:
- a "hardware shopping list" - in the terms of TOSCA requirements, which are based on specially designed TOSCA capability types
- a software image that the Orchestrator uses to launch such a unit - by means of a TOSCA artifact
- an ability to host application logic - modeled as a TOSCA capability of a special capability type
A VFC is an ONAP resource that represents a piece of application-level logic, which can be executed by a VDU.
TODO: explain the motivation for this separation of concerns, its advantages, use cases, etc