ActivityPub is a W3C Recommendation

By Christopher Lemmer Webber on Tue 23 January 2018

Having spent the majority of the last three years of my life on it, I'm happy to announce that ActivityPub is now a W3C Recommendation. Whew! At last! Horray! Finally! I've written some more words on this over on the FSF's blog so maybe read that.

As for things I didn't put there, that fit more on a personal blog? I guess that's where I speak about my personal life experience and feelings about it and I would say they're a mix of elation (for making it), relief (also for making it, because it wasn't always clear that we would), and burnout (I had no idea this process was going to suck up so much of my life).

I didn't expect this to take over my life so thoroughly. I did say this bit on the FSF blogpost but when Jessica Tallon and I got involved in the Social Working Group we figured we were just showing up for an hour a week to make sure things were on track. I did think the goal of the Social Working Group was the right one: we had a lot of libre social networks but they were largely fractured and failed at interoperability... surely we could do better if we got everyone in a room together! (Getting everyone in the room wasn't easy and didn't always happen, though I sure as heck tried, particularly early on.) But I figured the other people in the room would be the experts, the responsible ones, and we'd just be tagging along to make sure our needs were met. Well, the next thing you know we're co-editors of ActivityPub, and that time grew from an hour a week to filling most of my week to sometimes urgent, grueling deadlines (granted, I made most of them a lot more complicated than I needed to be by doing example implementations in obscure languages, etc etc).

I'm feeling great about things now, but that wasn't always the case through this. I've come to learn how hard standards work is, and I've been doing other specification work recently too (more on that in a coming blogpost), but I'll say that for whatever reason (and I can think of quite a few, but it's not worth going into here), ActivityPub has been far harder than anything else I've worked on in the standards space. (Maybe that's just because it's the first standard I've gotten to completion though.)

In fact, in early-to-middle 2017 I was in quite a bit of despair, because it seemed clear that ActivityPub was going to not make it in time as an official recommended standard. The Social Working Group's charter was going to run out at mid-2017, and it had already been extended once... apparently getting a second extension was nearly unheard of. I resigned myself to the idea that ActivityPub would be published as a note, but that there was no way that we would be able to make it to getting the shiny foil stamp of being an actual recommended standard. Instead, I shifted my effort to making sure that my ActivityPub implementation work would support enough of ActivityStreams (which is what ActivityPub uses as its vocabulary) to make sure that at least that would make it as a standard with all the components we required, since we at least needed to be able to refer to that vocabulary.

But Mastodon saved ActivityPub. I'll admit that at first I was skeptical about all the hype I was hearing about Mastodon... but Amy Guy (co-author of ActivityPub, and whose PHD thesis, "Presentation of Self on a Decentralised Web", is worth a read at the memorable domain of convinced me that I really ought to check out what was going on in Mastodon land. And I found I really did like what was happening there... and connected to a community that felt like what I had missed from the heyday of StatusNet/, while having a bit of its own flavor of culture, one that I really felt at home in. It turned out this was good timing... Mastodon was having trouble expanding the privacy needs of its users on OStatus, and it turns out private addressing was exactly one of the reasons that ActivityPub was developed. (I'm not claiming credit for this, I'm just talking from my perspective... the Mastodon ActivityPub implementation issue can give you a better sense of where credit is due, and here I didn't really do much.) This interest came right at the right time... it began to also drum up interest from many other participants too... and it pretty much directly lead to another extension to the Social Working Group, giving us until the end of 2017 to wrap up the work on standardizing ActivityPub. Whew!

But Mastodon is not alone. Today there are a growing number of implementers of ActivityPub. I'd encourage you, if you haven't, to watch this video of PeerTube and Mastodon federating over ActivityPub. Pretty cool stuff! ActivityPub has been a massive group effort, and I'm relieved to see that all that hard work has paid off, for all of us.

Meanwhile, there's a lot to do still ahead. MediaGoblin, ironically, has fallen behind on its own federation support in the interest of advancing federation standards (we have some federation code, but it's for the old pre-ActivityPub Pump API, and it's bitrotted quite a bit) and I need to figure out what the next steps are and discuss with the community (expect more on that in the next few months, and sure to be discussed at my talk at Libreplanet 2018). And ActivityPub may be "done" in the sense that "it made it through the standards process", but some of the most interesting work is still ahead. The Social Web Community Group, of which I am co-chair, meets bi-weekly to talk and collaborate on the interesting problems that implementers of libre networks are encountering. (It's open to everyone, maybe you should join?)

On that note, in a recent Social Web Community Group meeting, Evan Prodromou was showing off some of his latest ActivityPub projects ( and I'm paraphrasing here, but he said something interesting, which has stuck with me: "We did all that standardizing work, and that's great, but now we get to the fun part... now we get to build things."

I agree. I look forward to what the next few years of fun ActivityPub development bring. Onwards!