Recently, there was a discussion about generic #ActivityPub servers. Several people claimed that they were working on one, but it turned out that their "generic" servers only support activities defined in the ActivityPub specification. Such a server shouldn't be called generic. It is not difficult to build, neither it is an interesting concept because competing protocols (e.g. Nostr) already offer much more.
I've been writing a #FEP that describes how to build a real generic server. It is not finished yet, but I feel like now is a good time to publish it:
FEP-fc48: Generic ActivityPub server
This kind of server:
- Can process any object type, and can process non-standard activities like EmojiReact.
- Compatible with FEP-ae97 clients.
- Does not require JSON-LD.
I attempted to implement it when I was researching security properties of FEP-ae97 API: https://codeberg.org/silverpill/fep-ae97-server. Back then I didn't know what to do with side effects, but now I think that we can simply force clients to specify them.
Special thanks to 
@mariusormarius and 
@trwnhinfinite love ⴳ for their input.