Please give the resources a timetable. Not every resource is permanently available. Possibly share resources with other parties.
A resource needs availability times just like a provider. Days and times.
Other providers treat resources and providers the same. Everything can be combined with everything else.
We use connected resources for room reservation. So we need the calendar schedule for the resources.
It should also be possible to define a reservation priority for the resource or have the possibility to choose in which resource we wish to execute the service.
(already proposed in another concurrent solution)