In [ActivityPub], objects are identified through their id, which is a dereferenciable URI. For this, one adds a TXT record to DNS with name _apobjid and value corresponding to the URI of the ActivityPub object. If a domain name is then passed to a FediVerse application, it can then perform the DNS lookup, and resolve it to the ActivityPub object.
This FEP is inspired by [BlueSky], and it gets the FediVerse half of the way there. It allows one to look up the ActivityPub Actor from an associated domain name, it does not address the issue of diplaying the domain name instead of the FediVerse handle. One first step would be to include the domain name in alsoKnownAs. Then use some property of the actor to specify, which object to display.
Two other mechanisms to identify ActivityPub objects beside their id are currently in use:
The FediVerse handle username@domain.tld is commonly used as an identifier for users on the FediVerse. This handle can be resolved by performing a Webfinger lookup via
GET https://domain.tld/.well-known/webfinger?resource=acct:username@domain.tld
the activity pub object is then contained in the link with type application/activity+json.
The second method, that is less commonly used, is to provide a HTML link header of the form
<link
href="https://activty.pub/object/id"
rel="alternate"
type="application/activity+json"
/>
A FediVerse object receiving this HTML as a response to a lookup, can then parse it and use the link to lookup the corresponding object.
On a server supporting content negotiation, a request with Accept header “application/activity+json” will be either served or redirected to the corresponding ActivityPub object. The author does not a method to identify where the ActivityPub object is, as it is being directly served.
The following shows an example configuration for the domain mymath.rocks correspond to the actor with FediVerse handle @helge@mymath.rocks, i.e. the author,
$ dig _apobjid.mymath.rocks
;; ANSWER SECTION:
_apobjid.mymath.rocks. 7200 IN TXT "https://mymath.rocks/endpoints/SYn3cl_N4HAPfPHgo2x37XunLEmhV9LnxCggcYwyec0"
The corresponding object being
{
"@context": ["https://www.w3.org/ns/activitystreams","https://w3id.org/security/v1"],
"id":"https://mymath.rocks/endpoints/SYn3cl_N4HAPfPHgo2x37XunLEmhV9LnxCggcYwyec0",
"name":"Helge",
"preferredUsername":"helge",
"summary":"<p>I like Math, cows, and wrote <a href=\"https://codeberg.org/bovine/bovine/\">bovine</a>.</p>",
"type":"Person", ...
}
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