Presence

Can I be notified over HTTP when someone enters or leaves a channel?
Yes, this is supported using WebHooks. You can register for HTTP events to pushed to your servers using WebHooks whenever a client enters, updates the...
Tue, 1 Mar, 2016 at 1:07 PM
Why don't presence members leave as soon as I close a tab?
If you're using the javascript client, ably-js, you may have noticed that if you close a tab (or refresh the page etc.), it takes 15 seconds for any...
Wed, 9 Nov, 2016 at 8:45 PM
What happens if I exceed the number of members present on a channel?
To avoid any confusion about terminology used, the number of clients that can be attached and subscribed to a channel is unlimited. See the channel pub/s...
Wed, 7 Dec, 2016 at 8:08 AM
Why do you have a limit on the number of members present on a channel?
To avoid any confusion about terminology used, the number of clients that can be attached and subscribed to a channel is unlimited. See the channel pub/sub...
Sat, 18 Aug, 2018 at 6:05 PM
Can a single user be present multiple times on the same channel?
Yes, that is perfectly valid from our perspective.  For example, if a user is present on a channel in their browser and also on their mobile device, then th...
Fri, 5 May, 2017 at 6:57 PM
Can I change the length of the presence timeout?
This is not a feature we offer at this time.
Thu, 26 Jul, 2018 at 8:43 AM
I don't understand why I see so many presence messages in my stats. Can you help?
Ably's presence is a powerful feature that allows client devices to subscribe in real time to presence events such as as when users enter, update or le...
Sat, 18 Aug, 2018 at 6:04 PM
How can I see which channels are currently active?
You can go to https://rest.ably.io/channels?key=<redacted>, where <redacted> is the key you want to see the channels associated with.
Mon, 3 Sep, 2018 at 5:57 PM
How can I implement presence subscriptions efficiently, in terms of limits?
If you want lots of people to be present, but without necessarily listening for presence change events, tokens can be used to prevent all users from receivi...
Fri, 5 Oct, 2018 at 11:03 AM
What happens to the presence status of a client that abruptly disconnects?
When a client that is part of the presence set disconnects from the app, due to the app being closed or the network going down, the particular client will c...
Mon, 12 Nov, 2018 at 11:22 AM