current-gen AP servers do have an implicit dependency on HTTP and DNS. i've spoken with several people about creating a proof-of-concept AP server that supports gossip-based replication and a few other ssb-inspired features.
I find it rather disappointing (in ActivityStreams in general), by the way: on the first sight it's a part of the Semantic Web, but the approaches seem to differ from common ones, and the specification itself mentions that there's merely compatibility with one of the serialization formats (JSON-LD).
> but transport and actor resolution are not well specified
There's this for ActivityPub though: "Publicly facing content SHOULD use HTTPS URIs", and bits such as "The outbox accepts HTTP POST requests, with behaviour described in Client to Server Interactions", "clients MUST discover the URL of the actor's outbox from their profile and then MUST make an HTTP POST request". Authentication is not specified, but apparently de facto it will be some hacks on top of HTTP, too.
Putting those two together, it seems to mostly aim the popular nowadays combination of HTTP and JSON (just RDF/semweb-friendly).
Or to make my question more precise : would the gossip model be used only for data distribution and we would still have to register on a node, or would it allow to keep and reuse our data and identity should our usual node disappear?
the idea is to move the key that AP uses to sign JSON-LD objects to the client and do all of the crypto operations there.
a server in this model is an always-on relay for replicating data. you can submit a message to any relay and expect to have it show up on all interested servers.
unfortunately, this will also break compat with HTTP/DNS-based AP servers, but hopefully this is something that the maintainers will be open to supporting.
relevant threads:
https://b.9chan.lol/notice/279590
https://b.9chan.lol/notice/226866