@raphael Regarding your other post,
>...a different approach for ActivityPub software, putting the client at the center of everything and making the servers just specialized relays of ActivityStream messages
This is possible with FEP-ef61. Portable messages are self-authenticating, so it doesn't matter where they are generated, on the server or on the client.
However, I think the traditional (server-centered) approach also has its merits. There is a place for both in Fediverse
https://mastodon.communick.com/users/raphael/statuses/112453788068689232