ActivityPub extensions

This page exists to document extensions to the ActivityPub protocol. Extensions are developed as part of the SWICG.

Published extensions

None

In-progress extensions

Debatable about whether it's an extension, but see also ActivityPub and WebFinger.

uploadMedia

uploadMedia: Upload endpoint URI for this user for binary data. Part of the endpoints mapping. See ActivityPub MediaUpload.

Possible future extensions

This list has come from a variety of sources. Of particular note: pump.io's "protocol" label, ActivityPub's GitHub repo, IRC, and cwebber's blog.

Importing old posts into user inboxes when following someone new (such that their stream becomes "immediately usable" without waiting for future activity distribution)
The ability to change usernames
Distribution failover such that an admin could set up a secondary server which would then be tried for distribution if the primary server failed (similar to email's MX records)
Future distribution model - http://dustycloud.org/blog/an-even-more-distributed-activitypub/
Anti-abuse - https://dustycloud.org/blog/possible-distributed-anti-abuse/
End to end encrypted wrapped objects (which lack server to server side effects) - https://github.com/w3c/activitypub/issues/225#issuecomment-304938193
Revision IDs to detect and prevent race conditions - https://github.com/w3c/activitypub/issues/188
Object history (possibly related to revision IDs?) - https://github.com/w3c/activitypub/issues/155
Concrete auth protocols based on LDN (or whatever)
WebSockets(? also value in something like SockJS) interface for clients to get streams like the inbox sent to them in realtime
Priority flags - https://github.com/w3c/activitypub/issues/196
Actor profile discovery via rel= links instead of content negotiation - https://github.com/w3c/activitypub/issues/204
Direct message differentiation - https://github.com/w3c/activitypub/issues/196#issuecomment-304958984
Useful "extra" inboxes for clients (conceptually similar to pump.io's major/minor inboxes; could also be used to e.g. query for all direct messages)
Inbox search (very similar to above - i.e. an "extra" inbox constructed with the client's parameters, not the server's)