Hey, I am currently trying to understand a bit better what the Activity Pub allows and what it doesn’t as I am preparing a presentation on that topic.
On Lemmy I can join other servers without having to recreate an account. Does that also work for across Activity Pub supporting software? Could I join a PeerTube page and then post there? Could I upload videos? Could I join Mastodon or Pixelfed and post images?
And so I’d say this also answers your broader questions. Since Activity Pub doesn’t allow me to join other servers, it also doesn’t allow me to join other sites.
So a Lemmy post may be compatible with a Mastodon message sent to a group or something, that’s only because the messages Activity Pub sends are similar. But PeerTube is different software with different buttons, and the existence of those buttons on PeerTube doesn’t change anything about what buttons Lemmy has, and I can’t “login” to a PeerTube server with my Lemmy account, so I don’t gain any special abilities outside of what Lemmy can do.
The only way it would be possible is if Lemmy added a feature for uploading videos that sent the same kinds of messages to other servers that PeerTube sends. Then, if they did that, someone on a PeerTube instance could see these messages coming from Lemmy and interpret them on their server as a PeerTube video or something.
But all that Activity Pub allows is exchanging of information between sites. For them to interoperate in a way that makes sense, they need to exchange the same kind of information.
Good response! You were right. I thought that it would work similarly to SSO i.e. your instance works as an identity provider and your content is then generated on the other page, not send there.
Alright, so following the mail metaphor: lemmy is unable to send a video attachment so it can’t allow you to upload videos to peertube; however, activity pub could allow for that.
I think I have to read up on the exact definition of “group”.
Maybe I should create a new post for this but has there ever been discussions regarding SSO? So you have one identity across all fediverse services?
I’m not sure that would be the correct metaphore. Lemmy can send video attachement. But your lemmy account is not allowed to upload video to peertube so you can’t send any video.
There is also an economical reason : a video is ressource hungry.
So it is limited to watching peertube video. Let’s imagine 1000 lemmy users uploading video to peertube…
But this is a peertube limitation, right? Activity Pub itself provides the video information and peertube - due to whatever reasons (most likely the economical reasons you mention) - decides to not use that information / reject “the mail”. Is a message sent is only stored on the receiving end or also on the node I am sending it from?
Images and videos on Activity Pub are sent as direct links to the host.
So you can send text comments from Lemmy to peertube that will be replicated, and watch the video by “following” direct links to the host (it is done automagically in your browser or app).
This explanation on how images and videos are embedded while text messages are copied is really helpful!
Here you go.
Don’t know about Lemmy specifically, but there has been discussion on SSO in the fediverse in general. There is an FEP (Fediverse Enhancement Proposal) which lists some implementers. I have also heard the client-to-server API part of ActivityPub could be used for this, but I don’t think projects usually implement that (it’s optional). It should be theoretically possible to provide SSO for any fediverse project which has an API with authentication. I think. So sign in with Lemmy should be possible, but it’s up to those other projects to implement it.