Hi Cristoph, On Fri, Dec 14, 2018 at 04:34:05PM +0100, Christoph Jabs wrote: > Hello mynewt devs, > > I have a question regarding the mynewt-NimBLE stack. > > Whilst working my way through the code of the stack, trying to understand > the structure of it and how to use it, I came accross the functions defined > in nimble/host/include/host/ble_gatt.h for initiating GATT procedures. I > realized that the functions are all named ble_gatts or ble_gattc (and are > devided into two corresponding source files ble_gattc.c and ble_gatts.c) > and I assume this devides the functions in server or client side > functionality.
All correct. > However, a four functions seem to break that system. These are the > functions for sending notifications or indications to connections. My > understanding is that the BLE peripheral (the GATT server) sends > notifications to the BLE central (the GATT client). This seems to match the > fact that the functions for notifying and indicating are being called in > ble_gatts_tx_notifications. Why then are the notification and indication > functions labeled gattc? > > Feel free to correct me if i'm missing something or if I completely > misunderstand the things these functions do. From my perspective this seems > just a bit confusing. I agree that it is confusing. Notifications and indications are peripheral-side (server) procedures, so it is reasonable to look in `ble_gatts.c` for their corresponding functions. However, ignoring the Bluetooth spec for a bit, these procedures are logically client-side operations. They are unsolicited, and in the case of indications, the sender needs to listen for an acknowledgement. These operations have a lot in common with central-initiated procedures, and very little in common with the others. As such, the code implementing these procedures makes use of functions and data structures that are private (`static`) to the `ble_gattc.c` file, and as a consequence, these public functions must also go in this file. And since the functions are in this file, well... they are named with this file's prefix :). I'm not sure if this was the best approach. It is too late to rename the functions now (though I suppose we could add some `ble_gatts_...` aliases). At the time, I convinced myself that the naming was OK, because "client" and "server" are general descriptions of the functionality, and not directly derived from the spec. Chris
