Define "non-federated" server

[evanp]

In the Inbox subsection of Collections, we say:

Non-federated servers SHOULD return a 405 Method Not Allowed upon receipt of a POST request.

"Non-federated servers" is not one of our conformance classes.

https://w3c.github.io/activitypub/#specification-profiles

It's strange to have a requirement on a class of systems that don't implement one of our profiles.

[evanp]

Maybe a better way to define this is "API-only servers". These don't exist, AFAIK, but at least we would be defining something positive instead of negative.

[evanp]

Another option is to change this to a positive definition. A federated server should respond with a 201 Created for a valid activity (not sure that's well-defined).

We could also use the OPTIONS method. A federated server should include POST in the Allow: header of an OPTIONS response.

[evanp]

A last option is just removing the sentence entirely.

[snarfed]

Another minor but awkward bit here: section 2.1 seems to define "federated server" as implementing both C2S and S2S:

ActivityPub conformant Federated Server
This designation applies to any implementation of the entirety of the federation protocols.

[evanp]

"the entirety of the federation protocols" I think means the 'server to server protocol, or "Federation Protocol"
This protocol is used to distribute activities between actors on different servers, tying them into the same social graph.'.