Extrapolate the pattern for Retrieving objects to other non-HTTP identifiers

[evanp]

In "Retrieving objects", we define how to dereference an HTTPS URI -- and what should be presented when it is dereferenced.

We could maybe (?) request that this pattern is followed for other types of identifiers; for example, a DID identifier or an IPFS identifier should eventually resolve to an AS2 document.

It may be hard to come up with normative language on this, since different resolution mechanisms will be different.

[snarfed]

Agreed. Useful to mention non-HTTPS transports, good to avoid trying to actually specify them in any way.

[trwnh]

The important thing to emphasize here is that the semantics of HTTP GET can be applied outside of the HTTP protocol.

I'd use language something like this in "Retrieving objects":

Retrieving objects

ActivityPub objects MUST use a dereferenceable id, with a scheme that supports a method of obtaining an object's representation from its identifier.

Identifiers SHOULD use the https: scheme. When https: is used, the HTTP GET method is used to dereference the identifier.

Other identifier schemes MAY be used, provided that they have a method that is semantically equivalent to HTTP GET.