How to transfer data from one phone to another and how to make a vibration about the receipt of information even in a locked state?

Question

Android

Good day to everyone, I'm completely new to android development, I'm writing my first application based on Yandex maps, something like a mini taxi service option. I have 2 tasks in front of me, and I stupidly do not know where to start.
1) How to transfer location information from one phone to another (for example, the application client sends its coordinates to the driver application so that it arrives at that address, I'm interested in the technical side of which libraries to watch which android services to use for this, etc.)
2) Driver should receive vibration and beep alert even when the phone is screen locked. How to do this, what libraries to use, etc. And if there are code examples I will be very grateful.

Answer 1

In order to do this, you need your own server. Applications will communicate with it using http requests. The server can initiate communication with a push notification. Applications should not communicate directly.