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Comment by taurusnoises | Hacker News Reader

I have tried to wrap my head around how this works as a total outsider noob, and I just can not get it! But, I want to.

I get the email comparison (different platforms can all speak, so why not have social media be the same?). But, then the white sheets are just all php and python and all this stuff that doesn't make any sense (I know what they are, just not what to do with that info), and for better or worse doesn't make sense to anyone I know. I'm, like, doing the Odin Project, actively trying to learn, and I still can't really get it. How is this supposed to translate to anyone else?

But, again, I want it to.

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I don't think you need to understand anything about php or Python to understand this. I think the email comparison is the best metaphor.

Gmail and Yahoo and whatnot all speak the same language, "email". They've friended one another ("federated") and have unfriended spam mail servers. They've also settled on roughly the same design for their mail clients, but they didn't need to.

Unlike Gmail, there are a zillion Mastodon servers, because anyone can make it. And unlike email, the "ActivityPub" protocol can be used for a bunch of different uses. Mastodon cuts it up to look like Twitter, Pixelfed cuts it up to look like Instagram, PeerTube cuts it up to look like YouTube, etc.

Basically, Gmail is just one email server, and it speaks SMTP .

Similarly, Mastodon.social is just one Mastodon server, and it speaks ActivityPub.

In practice, I don't think you really need to understand it any further than the email analogy. I just tell those interested to sing up for Mastodon.social and see if they like it.

ActivityPub is a generalization of Email. Email gives you a cloud-hosted inbox that others can put stuff in. ActivityPub gives you both an online inbox AND a "outbox" that YOU can put stuff in that others can check out. Check out this diagram: https://activitypub.rocks/static/images/ActivityPub-tutorial...

The stuff here is called an "Activity" around "Objects". Follow request is a "Follow" activity with the "Actor" as the object. A tweet is a "Create" activity with the "Note" being the object. There's an entire vocabulary defined in the spec: https://www.w3.org/TR/activitystreams-vocabulary/#object-typ...

This way, all kinds of social platforms - from YouTube to GitHub - can be modeled in this general distributed pub/sub system.

>ActivityPub gives you both an online inbox AND a "outbox" that YOU can put stuff in that others can check out.

It's djb's Internet Mail 2000!

That's a term I haven't heard in forever. For those that don't know the reference: https://cr.yp.to/im2000.html

Basically you have e-mail, which is a protocol (actually a set of protocols, but ignore for now). Thus you can e-mail a protonmail user from your gmail/corporate account without any issues. However Twitter and Facebook are proprietary black box services and beyond using a Facebook-provided identity to create a Twitter account, there is no way to 'friend' a Twitter user on your FB account or interact with content in any way.

Then there comes a protocol called ActivityPub[1], which "e-mailifies" social networking. So far Mastodon and their goodreads clone are harvesting modest success.

I am a great fan of the goal, but not of the top-down approach W3C have taken with ActivityPub. For example LBRY solves this problem in a different way and is way more successful than all of Fediverse in total.

1. https://en.wikipedia.org/wiki/ActivityPub

> So far Mastodon and their goodreads clone

Had to look this up, I think you mean BookWyrm(?).

https://news.ycombinator.com/item?id=28420580

https://bookwyrm.social/

Yes, exactly this, thank you. It is actually quite good, shame that their main node seems to be out of capacity.

The W3 spec has a high level overview of how ActivityPub works.

https://www.w3.org/TR/activitypub/#Overview

This might help. If Twitter for some reason decided to migrate to the Fediverse, then you could login to their mastodon.social account, follow @elonmusk@twitter.com, and reply to Elon's tweets, all without having a Twitter account. And Elon and other people on Twitter would see your reply (coming from, say, @taurusnoises@mastodon.social) and could reply to you.

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