I know they’re quite different technically. But practically, what does ActivityPub unlock that was not previously possible with RSS and basic web tech stack?
I think I have an idea of the answer. RSS may provide a way for users to “subscribe” to content from a feed, equivalent of following and putting it in a unified feed.
But it does not have a way for users to interact with the poster, like comments or likes. This may be possible with a basic web stack though, but either users will have to make accounts on every person’s site, or the site has to accept no user auth. (but this could be resolved with a identity provider standard, like disqus does)
I suppose another thing activityPub does is distribute content to multiple servers. Not sure if this is really desirable though?
Anyways, did I miss anything?
The really intriguing thing about ActivityPub, at least to me, is it’s capability and potential to be a bridge for many other protocols.
For example, here’s ActivityPub via email: https://apubtest2.srcbeat.com/apas.html
That page also references the longstanding NNTP(Usenet)-email bridge that existed for the linux-kernel mailing list, so we could get ActivityPub to Usenet.
In fact there are a couple of RSS->Mastodon projects out there already, such as https://github.com/dariusk/rss-to-activitypub or https://github.com/jehna/mastofeeder
Do you know if they’re an ActivityPub-BlueSky bridge in the works?
Is there something about activity Pub that enables it do this, that other protocols or architectures wouldn’t have?
Depends on your POV.
In one sense, if ActivityPub can be a bridge between two protocols (e.g. RSS vs email) then it’s always technically possible to cut out the middle man. In that sense, no not really.
From my POV though ActivityPub shines because it’s more content agnostic. RSS is specific to feeds and posts, while email is for email, Bluesky is Bluesky (twitter), etc, but ActivityPub can handle video (peertube), images (pixelfed), forums - including likes and downvotes (Lemmy), microblogging (Mastodon), etc. (Note that the ActivityPub to email implementation I mentioned currently doesn’t handle likes/downvotes for example.)
With the possible exception of email, I’d also say that ActivityPub has something these other protocols do not - ownership over your own data. If you run your own instance for yourself, you always retain a copy of your content - you don’t have the situation of ello.co where if the site suddenly goes down without warning you lose years of work. Even if you use someone else’s instance, if that goes down you may be able to recover your content from another instance that was federating to it (retrieving content posted to kbin.social from the copy at fedia.io for example). That’s the beautify of federation.
(This is also true of traditional email, but things like gmail and Outlook - where the email is simply hosted on someone else’s server - are moving away from that.)