On multiplexing...

Our primary transport for our client libraries is WebSockets which we use to publish and subscribe to messages on any number of channels simultaneously.  Therefore all of our client libraries support multiplexing and will efficiently use a single transport to help maximise throughput, minimise bandwidth consumption and reduce power & battery drain.


On channel groups...

Channel groups are a concept that other providers use to describe a system whereby channels can be placed into groups to work around the inherent limitations they have in the client to dynamically subscribe or unsubscribe from channels.  Ably does not support channel groups because with our client libraries you can add or remove subscriptions to channels dynamically at any time.  So far we have not found a use case where channel groups are needed instead of simply subscribing to the channels a client needs access to.