Going to write a tutorial on building a "Hello World" service for the fediverse as soon as I can figure out how to federate with the fediverse.

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This is exactly what I want to do: ...but things seemed to have changed in a year. So I'm looking at Peertube as well as Mastodon; have Webfinger support; getting ActivityStreams in there; I think I need Pubsubhubbub now? What the hell is "salmon" and this "magic key" that I apparently need?

Okay some of that stuff is from OStatus and not needed for a pure application. Test accounts now show up in search; working on posts next.

GETting an outbox works; correct number of posts shows up. Now I guess I need to keep track of followers on my end to know where to deliver events when a new post is published.

Still working on sending the `Accept` activity back after receiving a `Follow` on @write_as. If I don't sign the request Mastodon rejects it.

I'm reading that there's no official authentication method in the spec, but that HTTP Signatures should be enough, but also that I might need Linked Data Signatures for things that'll get passed around (like posts). Will see.

I'm now looking at and Mastodon's code to figure out what data to send.

Got HTTP Signatures in, but Mastodon is giving me this error:

OpenSSL::PKey::RSAError (Neither PUB key nor PRIV key: nested asn1 error)

Looking more into things, it doesn't seem the Go crypto libraries create keypairs that are compatible with OpenSSL, so switching to this one for generating the keys.

Tried that library, but everything broke when I had different versions of OpenSSL on my dev machine and server. Now just calling the CLI from the app.

Keys look good now, Mastodon is accepting my requests, but the Accept activity isn't having any effect. Going to start digging some more

Accept activity still not having an effect, despite seeing a 202 response in the logs. So went ahead and started sending Create activities for new posts, and oddly I'm getting a 401 back for that. Think I've done enough for tonight

Follows work! Finally! I was missing the `@context` property 🤦‍♂️

Now to see about those posts.

Was going to try to implement LD-Signatures to see if that's what's giving me the 401 on Create activities, but there's nothing out there already for Go, and I'm not comprehending the specs for the signature algorithms right now (I got the headers part, don't understand what part of the payload to sign).

Going to start on a simple read-only server so I can follow other accounts, see what they're sending out, and compare.

Sooo with some additional logging on my server I confirmed it's the HTTP Signature verification failing. If I cheat and disable that on my instance, posts show up! 🎉

But apparently Go's libraries don't create a valid signature -- and neither does openssl when I call the CLI with the parameters I did. If I could figure out what arguments are passed to create the digest, I could quickly make it work. But that's enough for today too.

Success!! Got post federation working! 💥 I figured out the HTTP Signature issue -- mostly turns out I had a bug fetching the correct keys for individual blogs.

Now I'm cleaning up code, submitting PRs for the libraries I used, and adding things I skipped, like handling unfollows.

Write-up coming soon, and with any luck, it'll be live on @write_as this week.

@matt I'm not sure how helpful this is for your use case, but you can toot anything coming from a RSS feed (i.e. a blog).

@quimgil Thanks, though I'm actually trying to enable federation for blogs on @write_as, i.e. making the individual blogs there followable accounts in the fediverse. So just trying to understand all the protocols that need to be implemented to get there

@wakest Awesome! I didn't know about it before. Will definitely play around with it

so federation between ActivityPub servers is live?
That would be great! From a short look at the webpage it wasn't obvious to me that can federate.

@paulfree14 Not quite yet -- still need to clean up some code and make sure federated message delivery is reliable. But it should be ready this week or next!

oh, look @deadsuperhero gets federation for their blogging sytem running soon.
(view the post I'm replyn)

@matt @write_as Really excited to see cross-platform federation for AP blog platforms.

@sean @write_as Yep! Me too. And I'll be working on some of this again with @read_as after hits v1.0.

@wakest Yep :)

Just the basics for now to let people follow blogs from the fediverse, and see what it all looks like. Then I can give some more thought to any new / interesting things could do with federation

@wakest Glad you are too 🙌 Will keep you updated!

@matt very cool! I love the minimalist style of the site

@sonya Thanks! Going to try and maintain that as I add features for the fediverse 🙂

@matt Gargron wrote a couple blog posts on this. Hopefully, he'll keep writing these posts so people get a better understanding of what's required.

I'm not pointing this out to discourage you, though. The more how-to articles we have, the better. Having articles from the lead developer of the largest fediverse project makes it easy for any developer to get started, but I want to see how other developers go about implementing AP.

@0x1C3B00DA Yep, that post helped a lot and was perfect timing for me. But there's still a ton of reverse-engineering I had to do to learn everything, especially for building support on an existing platform with a ton of users.

I do hope he keeps sharing his knowledge though! And I know @dansup mentioned he was working on something similar, which I'm looking forward to.

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