File transfer/large data transfer example NRF Connect sdk

Hi,

I am trying to transfer a dataset of over 100k, via a custom service from a peripheral device.

There are many posts in this forum that describe ways to do this but none seem to apply to the newer nrf Connect SDK. I am using nrf connect 1.7.1 with the VSCode extension.

The peripheral_uart example is often quoted as being a good starting point, but i can't seem to find where i would start some sort of Send data->wait for data sent event-> send next part, kind of cycle. The throughput example appears to transfer a large data set, but i am struggling to interpret that service as it is quite large. 

Is the advised way of doing this still calling notify on a characteristic? I have attempted to call Notify inside an on_sent callback but the code doesn't appear to call callbacks when already executing inside of one.

I would be very grateful if anybody could point me in the right direction towards initiating a large data transfer from a peripheral device.