As I understand it ActivityPub uses a combination of push notifications at time of publishing and pull notifications at time of subscription/query for objects?
It's a mix of pushing and pulling. When something happens, the server pushes a notification ("activity") to other servers. But recipients often need to pull additional data, such as user profiles or related posts.
Duration of caching is set by the instance admin I take it?
Yes, and it also depends on the software. Some applications may keep cached objects forever and only prune cached media (because objects don't require much space).
Regarding Authorship, if there wasn't an issue then ATProtocol devs wouldn't have made it the cornerstone feature of their network
Moving in ActivityPub world is difficult because authorship is tied to a specific server. We can solve this problem by using cryptographic identities and signing everything, like ATProto and Nostr do.
I'd like to know how delete requests propagate, when the "Object" is deleted does a request to clear cache go out to all federating instances?
Deletes and edits are usually sent to followers of a user or a community. Delivering them to all known instances is not practical.
General_Effort@lemmy.world 8 hours ago
Worry more about the bandwidth. Your instance would have to serve your content to all these 100M users. The way it is, much of the load goes to the instance where a user is registered. That means that an instance can control hosting costs by closing registrations.
There’s the fundamental problem. What you think of as “your” data, other people think of as “their” data. That can’t be resolved. What’s worse is that controlling “your” data requires controlling other people’s computers and devices, as with DRM.