How can a microcontroller send data to a server?

Question

Microcontrollers

Hello, I'm thinking about a research project in which I develop web applications (yes, not too trite), but the peculiarity is that this application will need to receive GPS data from microcontrollers.

The fact is that I am developing a web application, but I leave the API through which microcontrollers, in theory, could send data.

The question is, what is the most common way microcontrollers can send data to servers? (The controller itself is supposed to have some kind of 3g or 2g modem into which the SIM card is inserted) Do they use their own protocol or can they use http? (here it is worth noting that microcontrollers are probably not supposed to be the most powerful)

Answer 1

0) Terminology. A microcontroller is usually a microcircuit and only a microcircuit. Which contains a RAM, a computing core, some peripheral devices (for example, a wi-fi stack, like ESP8266).
It is impossible to insert a SIM card into the microcontroller, because it is impossible to insert a SIM card into a microcircuit.
A SIM card can be inserted into a slot on the controller board , on which a microcontroller, wi-fi antenna, power converter and other blocks can be located.
1) The architecture of solutions can be very diverse - the controller can access the Internet on its own, or it can use an intermediate server for this.
Depending on this, they use either HTTPS, as the main protocol for secure communications on the Internet today, or MODBUS (within the local network of controllers with a gateway to the Internet), or their bike.
Using some protocols on the Internet other than HTTP (S) immediately drags along a bunch of problems like "but my provider cuts ports."
Using HTTP entails "S in IoT stands for Secure" problems. Your traffic can be listened to and modified by anyone, as well as embed ads in it.
Conclusion. If your controller looks directly at the internet, use HTTPS / WebSocket. If through the gateway - use MODBUS.
In order to use a bicycle solution, you need to name at least three fatal flaws listed above. The statement "I didn't invent this" is not a fatal flaw in the technology.

Answer 2

A GSM modem for such tasks is usually implemented as a separate module. There are also modules for other networks - Ethernet, WiFi. Microcontrollers of the ESP family already have WiFi on board, out of the box.
There is no specific protocol. What you program will be, including http.

Answer 3

gsm-2g-3g-4g-*g wifi bt lorawan nb-iot
protocols is also a one-piece cart.
Whatever you have access to, use it.