I’ve completed a proof-of-concept implementation of ActivityPub in Quanta (Java Language), so anyone interested in ActivityPub for the SpringBoot+Java+TypeScript tech stack may also be interested in Quanta. I used the ‘Smitherene’ project (the only other Java implementation I’m aware of) to get past some of the tricky parts (thanks Gregory! @grishka ), in addition to having to reverse-engineer Mastodon without being a Ruby developer, and definitely getting AP up and running in a new language is not all that trivial. You can’t really just read the spec and go do it.
So I hope my cobbled-together code may be helpful to some Java developers.
The Quanta Platform itself has far more than just Fediverse features, and is a powerful collaboration tool unlike any other. With Quanta you create a persistent data structure that you personally own, rather than just dumping messages into a stream that you can never find again.