The current GATT server API and underlying code does not support notifications for hosted attributes. This requires a remote central to keep polling versus requesting a notification when the value changes.
This involves,
.) Adding a method to the Chrome Bluetooth API which allows an app to send a value changed notification to the remote central.
.) Wiring up the StartNotifying/StopNotifying DBus calls and remembering the notifying state.
.) Sending a signal to BlueZ when the user requests a send notification on an attribute value (if the remote central has requested notifications).
Comment 1 by bugdroid1@chromium.org
, May 12 2016