I found this article from earlier this year: https://blog.discourse.org/2025/04/discourse-and-the-fediverse/

However, I haven’t come across that much content from Discourse platforms over here on Lemmy/Piefed. Is there more work to do with the plugins, or should we work with organizations running Discourse to help them connect with us?

For example, the threadiverse communities for OpenStreetMaps is relatively small, and being able to see / contribute to community.openstreetmap.org would be amazing.

  • Pamasich@kbin.earth
    7·
    2 days ago

    Discourse decided to do its thread context in a way that’s currently incompatible with projects like Mbin or Lemmy. Those expect threads to be represented by some kind of post (Page, Article, Image, etc objects), while Discourse decided to use an OrderedCollection, with the first item being the opening post.

    Even if Lemmy decided to add support for OrderedCollection threads, there’s another issue though: the barrier for initial federation is too high. Discourse only gives you the fediverse handle of its categories, but to federate them in, you need their JSON-LD URL, not the handle. And Discourse decided to use separate URLs for its HTML and JSON-LD pages, with no way to derive the latter from the former. So to initiate federation with a Discourse category, you have to manually do a WebFInger query to get its URL to then give it to your instance. I think most people probably fail this hurdle, either out of laziness or lack of know-how.

    Also, I don’t know about Lemmy, but the Mbin instance I’m using seems incapable of processing Discourse categories anyway. Not sure why that is.

    That means Lemmy is entirely reliant on Discourse users replying to posts that are visible to Lemmy, similar to Lemmy-Mastodon interaction. But with less users, hence less overall interaction frequency.

    • julian@activitypub.space
      6·
      1 day ago

      Hey! Thanks for the concise reply. There’s a lot of technical stuff I can say about Discourse and such, but because I am the maintainer for NodeBB it is probably in my best interest to keep my mouth shut as we directly compete!

      Anyhow, the OrderedCollection stuff is actually all from me. I’ve been working as part of the Threadiverse working group to bring intercompatible formats to all threadiverse software, which besides Discourse and NodeBB, includes Lemmy, Piefed, and Mbin.

      The OrderedCollection enables software (like NodeBB) to quickly backfill entire topics. This is a huge problem on the microblog-side of the fediverse, and is not really a problem on the theadiverse, since there is already strong support for synchronization. However, smaller instances often do run into issues where they can’t ever “catch up” on old posts because there’s no way to get those posts. (e.g. start following a new community, you can’t read any of the old content)

      To that end, Lemmy and Piefed have (or soon will) ship code to allow software to backfill using OrderedCollections. They don’t use them yet, but they will provide them. It helps software like mine because I will then be able to see entire threads from communities I don’t even know about or follow. It’s a huge boost to discovery! :smile:

      > while Discourse decided to use an OrderedCollection, with the first item being the opening post.

      NodeBB also does this, but they’re not incompatible per se. You’ll see NodeBB topics showing up just fine on Lemmy and Piefed (see activitypub@community.nodebb.org or general), and that’s because NodeBB does the extra step of announcing OP and replies, just like Lemmy/Piefed.

      Importantly, Discourse does this too, but because of the inability to find Discourse categories, I don’t think it’s easy to follow them. Chicken and egg, really. The way the AP integration in Discourse is built-out, it is more insular by design. Threads from Discourse only ever go out to the fediverse, you can’t post in from the fediverse. That makes those communities much more insular by design and severely limits discovery.