Which protocol does Node RED get data from Firebase

[mixaobo]

i'm doing thesis, and using node red right now. i'm using ESP32 to push data to firebase and i ask this question too and this is what i get:

Google does not provide the websocket end point to connect to Firebase server directly. They provide the APIs (in SDK) for all their Firebase products included RTDB, for various platforms e.g JavaScript, Android, iOS, REST etc.
Only REST APIs are suitable for internet capable devices with limited resource which is not depending on platform or OS.
That's is the only approach where we use to communicate to Firebase using HTTP request to the REST API end point.

As i know, Firebase use websocket to get or push data to client. so which protocol do you use to get data from node red