[SOLVED] Example BLE GATT Server using C++

Example BLE GATT Server using C++

I'm trying to create BLE GATT services on my Raspberry Pi 4 using C++. Have searched for a while but wasn't able to find useful hints/examples.

More details: I'm able to create GATT services and characteristics using commands:

#bluetoothctl
[bluetoothctl] menu gatt
[bluetoothctl] register-service 0xFFFF #
[bluetoothctl] register-characteristic 0xAAAA read,write #
[bluetoothctl] register-application #

and I want to achieve the same using C++ codes.

I have found the definition for void RegisterApplication(object application, dict options) in https://github.com/Vudentz/BlueZ/blob/master/doc/gatt-api.txt, but it doesn't provide many details. My question is: For this RegisterApplication function, what should I put for the 'object application' and 'dic options'? Is there any example in the format of

g_dbus_proxy_call(
        Proxy,         
        "RegisterApplication",       
        Params,                       
        G_DBUS_CALL_FLAGS_NONE,      
        -1,                  
        NULL,
                NULL,
                NULL);

showing how the "params" should be constructed for my service and characteristic (registered using commands) above?

Solution

You need to build your BLE GATT service hierarchy in D-Bus and then with the RegisterApplication tell BlueZ where the top-level of the service is located on D-Bus.

To use D-Bus parlance, the local BlueZ service needs to be created with D-Bus objects and then published. It is the D-Bus object of the published local BlueZ service hierarchy you've created that is the first argument of RegisterApplication

More information at: https://github.com/Kistler-Group/sdbus-cpp/blob/master/docs/using-sdbus-c++.md#using-d-bus-connections-on-the-server-side

You might also want to look at the following project to see how they did it: https://github.com/nettlep/gobbledegook