how to know a client connects to/ disconnects to as a gatt server?

[YFJiang]

Hello,
how to know a client connects to/ disconnects to as a gatt server? Is there a session exists inside BlueR?

[surban]

There is no way to know whether a client is connected to a GATT server in BlueZ.

If you need that information, the client should subscribe to a characteristic, which will cause a notification session to start. See CharacteristicNotify.

[YFJiang]

Thanks. But no way to know when a client is disconnected, right?

[surban]

If you use the IO-based method, you can use CharacteristicWriter::closed to be notified when the notification session ends.