One of the many itches I have been scratching, as part of taking my social media contributions out of silos, is how to keep track of what my friends are up to. So, we’re talking about bringing the familiar social networking concept of friends, subscriptions and update notifications to a distributed social network like Idno, an Elgg/Elgg multisite node, or an Indieweb site.

Existing systems, like PuSH, seem a little to complicated for my liking. I wanted something I could get up and running in about an hour, and test using curl.

I expect other people in the Indieweb community are thinking about this too, but I couldn’t find anything with the 30 seconds of googling I had time for, and since I needed it I thought I’d throw my hat in the ring…

Outline specification

• Two sites/profiles: Alice and Bob.
• Alice wants update notifications from Bob.
• Alice’s site looks at Bob for subscribe endpoint.
• If found, Alice’s site sends POST containing Alice’s profile URL to the endpoint:
  

  subscriber=http://alice.com/profile/alice&subscribe=http://bob.idno/profile/bob

  Note: Bob’s endpoint is specified for multi-user situations, allowing the system to know which user we’re subscribing to.

• OPTIONAL: Alice and Bob mine each other’s profiles for MF2 data, one could also do key exchange at this point for any secure messaging or authentication for syndication of private posts.
• When Bob creates or updates a post, he discovers Alice’s endpoint and sends a POST containing the permalink, e.g:
  

  subscription=http://bob.com/foo+bar/

• Alice checks to see if permalink is from recognised domain (Optional, but recommended).
• Alice visits the permalink and parses MF2, extracts the author and checks that the author URL is in the subscription list.
• Alice then uses the MF2 content to produce a feed, or pop up a notification, whatever.
• If Bob deletes a post he sends a DELETE containing the permalink to Alice’s endpoint, e.g:
  

  subscription=http://bob.idno/foo+bar/

• If Alice wants to unsubscribe/unfriend she sends a DELETE mirroring the initial subscription request to Bob’s endpoint, and then (optional, but recommended) ignores any future post from user.

Crucially, it doesn’t require firing ATOM blobs around or maintaining extra feeds of data.

Handling popularity

An obvious problem with this proposed spec is how one handles a situation where a user has many subscribers. Here, we may want to update the spec or use a different technology, but the vast majority of people will likely only have a couple of hundred people in their network, tops.

I’ll probably be building this functionality out as an plugin for a couple of client sites in a couple of days, and I’ll post implementations when I have them, but let me have your comments below!