It doesn't exist and is very hard to build :)

I can contextualize this a bit, I think I had some ramblings elsewhere. Let me see if I can dig them up.

Oh, there's a bit of discussion in T5364. I think there are two ways to build the connection stuff:

1. We can store the information in the database, and have the JX.Leader make an Ajax request every few minutes.
2. We can store the information on the Aphlict server, and update it when Websockets connect and disconnect.

The tradeoffs of (1) are:

• PRO: Easier to build.
• PRO: Other applications can easily query the table if we want to do more stuff with this.
• PRO: Information is authenticated (no figuring out if someone's online unless you can see the information).
• CON: Slightly more expensive to scale, although not hugely so.
• CON: Less precise, and we may miss signoffs. Making it more precise involves higher load.

And pretty much the opposite for (2):

• PRO: Uses slightly fewer resources (we can figure out status almost-for-free on the Aphlict server).
• PRO: More precise about when users connect/disconnect.
• CON: Harder to build.
• CON: Applications can't cheaply/easily query it.
• CON: Information is not authenticated.

Overall, I think we should just hold this for a while. It does not seem hugely valuable to me. I lean toward (1), but there might be other use cases which come up which make having this available in Aphlict or in other applications an obvious win and push it one way or the other.

Idea: Displaying Last-Seen: 5 minutes ago should already help many people and might not require you to track open connections.