Clarify the exact role of the registry and the term virtual registry

[s4b7r]

@s4b7r, @martin-held-hereon could you elaborate on "virtualize registry"? I missed this discussion.

We tried to cover that discussion in the request-specs as well. You can find it under "exact role of the registry". However, I have to admit we went over that kind of quick and did not formulate it as thoroughly as the first parts. I will try to make that a bit clearer and prepare a pull request.

To summarize quickly: The idea is that we could have a central registry, but that the spec so far is agnostic to that. The reason being: If some additional software component in your client sends the same query to multiple endpoints (e.g. for available types at the endpoints), this would be in a way a virtual registry: just a point where information of multiple endpoints is collected and relayed. "Virtual" because there is no extra host/service that makes up that registry but it is an additional software step. If we do the specification of that "registry interface" right, there is nearly no difference whether that registry is inside the client software, on a dedicated central host, or even multiple registries are hosted somewhere, e.g. if you need one specifically internally in your own institution.

Originally posted by @s4b7r in MADICES/MADICES-2024#10 (reply in thread)

[s4b7r]

@edan-bainglass you can assign this to me, if that's possible. I will try to improve that description.