What if we had a P4 for ActivityPub?

[evan@activitypub.space]

P4 is a system-independent programming language for network devices like switches and routers. It lets developers define device behaviour like forwarding packets, quality of service, and traffic shaping. It's event-based; it defines what the device should do as it receives packets on a network interface.

What if we had a similar language for ActivityPub servers? You could define rules for what to do when different Activity objects hit an inbox or outbox. It could be defined to implement the basic flows in the ActivityPub specification, like Follow/Accept/Reject/Undo and Create/Update/Delete. But it could also be used to define other protocols, like geosocial interactions, groups, and events. Unlike P4, it would need to deal with persistent storage, but otherwise it could be quite similar.

I think some servers have a milter-like programming interface. Pleroma, maybe? It would be interesting to generalise support for that, or something similar, into a general-purpose high-level social programming language.

[thisismissem@activitypub.space]

This does exist, Pleroma has the Message Rewrite Filters or MRF functionality. There's also ActivitySieve or ActivityColander I think it was called, which attempted to do similar.

I've personally been arguing that we need federation management via policies more akin to a firewall: https://writings.thisismissem.social/moving-beyond-the-false-dichotomy-for-federation-management/