ActivityPub is a federated social networking technology popularized by Mastodon.
Account portability is the major reason why we chose to build a separate protocol. We consider portability to be crucial because it protects users from sudden bans, server shutdowns, and policy disagreements. Our solution for portability requires both signed data repositories and DIDs, neither of which are easy to retrofit into ActivityPub. The migration tools for ActivityPub are comparatively limited; they require the original server to provide a redirect and cannot migrate the user's previous data.
Other smaller differences include: a different viewpoint about how schemas should be handled, a preference for domain usernames over AP’s double-@ email usernames, and the goal of having large scale search and discovery (rather than the hashtag style of discovery that ActivityPub favors).
Using double-@ user identifiers for actor discovery is not an ActivityPub feature. It's a bastardization of webfinger resource search added and popularized by Mastodon.
In ActivityPub URLs are the identifiers, be it for actors or anything else. And the URL can be just of a domain, therefore it's perfectly possible to have domain named identifiers.
Until trademark laws come into play, and you find yourself obligated by law to give up your domain username to a big corporation. (A famous example in France is “Milka vs. Kraft Foods”, the court favored the big corporation’s registered trademark over Mrs Milka’s name.)
Granted, my comment doesn’t add much to the discussion, since this domain ownership issue would have been a problem in ActivityPub too.
This is not a problem because the atproto has true account portability, so your domain getting seized is not the end of the world, unlike in activitypub.
> Until trademark laws come into play, and you find yourself obligated by law to give up your domain username to a big corporation.
This wouldn't be a big deal in practice (besides losing the domain). Domain usernames are just the combo of you telling Bluesky "I intend to use this domain name" and then you placing a TXT record on the domain to prove you own it. If you want to change domains (or, are forced to), you just give them the new domain name and you set another TXT record (just like if you had set up a domain name as a username for the first time). The underlying DID is still yours.
That's also not how atproto domain usernames are implemented.
The identity is just a public key, basically. There's a resolution service which uses domains, but you can move the identity, with all the data, to another one.
Well, now it's up to the person who owns milka.fr so if it's kraft... No issue.
If this isn't and they complain, it has to go to litigation.
And one would think that they own a domain for their products already so it should be all good.
ActivityPub is a federated social networking technology popularized by Mastodon.
Account portability is the major reason why we chose to build a separate protocol. We consider portability to be crucial because it protects users from sudden bans, server shutdowns, and policy disagreements. Our solution for portability requires both signed data repositories and DIDs, neither of which are easy to retrofit into ActivityPub. The migration tools for ActivityPub are comparatively limited; they require the original server to provide a redirect and cannot migrate the user's previous data.
Other smaller differences include: a different viewpoint about how schemas should be handled, a preference for domain usernames over AP’s double-@ email usernames, and the goal of having large scale search and discovery (rather than the hashtag style of discovery that ActivityPub favors).
from https://atproto.com/guides/faq