Bridge groups

[voxpelli]

Whether a typical chat should be in Bridgy Fed is handled in #1425, but looking into eg. Matrix I realized that chat rooms are a subset of groups and groups of some kinds could be interesting to support in be in Bridgy Fed.

One concrete example would be:

Bridging IndieNews to Lemmy – bridging link aggregation groups / communities between the IndieWeb and the Fediverse.

I'm not sure whether there's any equivalent on the AT protocol yet, but eg. Matrix seems to be oriented fully around "groups" in the shape of rooms.

Some things to consider / note:

• Only groups with public content should probably be considered
• How to bridge to groups that require membership? Only support groups like IndieNews that require no membership to post?
• In Lemmy a user and a group can have the same name – so name is not enough to identify an entity over there, one needs to know if its a group or an account as well
• Should only explicit groups be supported or should implicit groups like hashtags also be considered? _I would treat them as out of scope, compare eg. in IndieWeb explicit <a href="https://news.indieweb.org/en" class="u-category">indienews</a> vs implicit <span class="p-category">indienews</span>)_
• A post published to my timeline can be submitted to one (or more?) groups – it should then be bridged both to those who follow my account and to those that follow the group?

Originally posted by @voxpelli in https://github.com/snarfed/bridgy-fed/issues/1425#issuecomment-2442034675

[voxpelli]

Plumbing notes: Groups in Fediverse / IndieWeb

Eg. Lemmy has rooms / groups – they call it "community" – and these are as possible to discover through WebFinger as user accounts are, see eg: https://fedidevs.org/reference/webfinger/#app-lemmy-handle-lemmy_supportlemmyml There they identify it with:

  "properties": {
    "https://www.w3.org/ns/activitystreams#type": "Group"
  }

In the IndieWeb the wiki brings up hashtags as one example of a group-style thing, but I think the best example is how one submits to news.indieweb.org using u-category:

<a href="https://news.indieweb.org/en" class="u-category">#indienews</a>

Originally posted by @voxpelli in https://github.com/snarfed/bridgy-fed/issues/1425#issuecomment-2441242711

[voxpelli]

Plumbing notes: Bridging related aspects about Matrix

On the topic of Matrix: It unlike most other standards have an official standard for bridging: https://spec.matrix.org/v1.12/application-service-api/#third-party-networks / https://spec.matrix.org/v1.12/client-server-api/#third-party-networks

Instant Messaging is also only of plenty of plenty of Modules supported on Matrix: https://spec.matrix.org/v1.12/client-server-api/#modules A microblogging-style module could probably exist eventually, but already when MSC1767: Extensible events in Matrix (accepted in https://github.com/matrix-org/matrix-spec-proposals/pull/1767) is supported one should be able to do something like this to losslessly bridge ActivityPub to Matrix with clients able to progressively enhance to use the full ActivityStreams object:

{
    // irrelevant fields not shown
    "type": "m.message",
    "content": {
        "m.text": [
            { "body": "<i>Hello world</i>", "mimetype": "text/html" },
            { "body": "Hello world" }
        ],
         "org.example.activitystreams": {
            "id": "https://rhiaro.co.uk/2016/05/minimal-activitypub",
            "type": "Article",
            "name": "Minimal ActivityPub update client",
            "content": "Today I finished morph, a client for posting ActivityStreams2...",
        },
    }
}

Originally posted by @voxpelli in https://github.com/snarfed/bridgy-fed/issues/1425#issuecomment-2441242711

[snarfed]

Thanks for filing @voxpelli, and for all the details!