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   Sebastian Jambor (crepels@mastodon.social)'s status on Thursday, 21-Dec-2023 20:18:15 JST Sebastian Jambor

   New blog post: Understanding ActivityPub - Part 4: Threads

   A first detailed look into how Threads implements ActivityPub. Learn about the data that is shared (or not), an interesting implementation of HTTP signatures, and Threads' take on quote posts in ActivityPub.

   https://seb.jambor.dev/posts/understanding-activitypub-part-4-threads/

   #ActivityPub #Threads #Fediverse

   • Tim Chambers repeated this.
   • Embed this notice
     Sebastian Jambor (crepels@mastodon.social)'s status on Saturday, 06-Jan-2024 07:15:39 JST Sebastian Jambor

     in reply to

     • Jahfer

     The weird implementation of HTTP signatures seems to have been a bug in Threads. It is now fixed and the signatures work as expected. I updated the blog post accordingly.
     Thanks @jahfer for looking into this!

     Fediverse Report repeated this.
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     Jahfer (jahfer@mastodon.social)'s status on Saturday, 06-Jan-2024 08:44:35 JST Jahfer

     in reply to

     • Mike P

     @crepels @FenTiger I spent *way* too long trying to figure out how to get my library (https://github.com/jahfer/clj-activitypub) to talk to Threads. Thank you! Your post was the thing that helped me to pull an actor document.

     Being stubborn, I tried to get to the bottom of why the instance actor stuff was required. Turns out...it's not! Threads just requires that the signing actor has a `url` field, which isn't common except for the instance actor. How anticlimactic 😑 I'm going to flag this to the Threads folks.

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     Sebastian Jambor (crepels@mastodon.social)'s status on Saturday, 06-Jan-2024 08:44:36 JST Sebastian Jambor

     in reply to

     • Mike P

     @FenTiger Thanks :)

     I can't really make sense of the instance actor requirement. I only tried this from ActivityPub.Academy (i.e., Mastodon); it would be interesting if there are any differences with other services. If you try this out with your implementation at some point, I'd be interested to know what you find.

     Tim Chambers repeated this.
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     Mike P (fentiger@mastodon.social)'s status on Saturday, 06-Jan-2024 08:44:37 JST Mike P

     in reply to

     @crepels Nice article! In particular, this is the best explanation I've seen yet of the "infinite signature recursion" problem, and the way around it.

     I haven't tried to talk to Threads from my own toy implementation yet. I have a suspicion that the "instance actor" requirement is going to give me a headache.

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     Sebastian Jambor (crepels@mastodon.social)'s status on Thursday, 11-Jan-2024 06:28:37 JST Sebastian Jambor

     in reply to

     • Pcottle

     Quote posts in Threads now include a link to the ActivityPub data of the quoted posts. This makes it possible for Fediverse services like Firefish and Misskey to fetch the quoted post and show it inline in the quote post. I updated the blog post with some information on this https://seb.jambor.dev/posts/understanding-activitypub-part-4-threads/

     Thanks @pcottle for the heads-up, and for some information about design choices that went into this.