What interface (API) to use for raw socket exchange between server and piece of iron (stm32)?

Question

API

All the best!
There is a server (PC, python) and a client (on stm32) connected via ethernet. Communication via raw socket.
Basically the data (requests) comes from the server!
What is the best API to implement/use?
The requirements are simple:
1) simple parsing of commands on the hardware side: determining the beginning of the command, the command, parameters, the end of the command - in case of sending commands in one package. Those. so that you can use switch case :)
2) text commands (something like AT commands) (for ease of viewing in wireshark)
3) I would not want to use third-party libraries (from IoT, smart homes, etc.) but if they give some advantage, it would be possible to use
4) for a minimum of resources
5) and probably most importantly, I would like to use a "beautiful" API, where everything is "beautiful")
What do you recommend? AT commands or plain text like " < START cmd='some_model' Height='3' Width='3' > "
Perhaps you have already done/implemented something similar?

Answer 1

Json is no longer in vogue?

Answer 2

AT commands, IMHO, are not the most convenient format - readability is bad for a person, but for a controller - text is text.
Option 1 - options on the topic of text protocols - JSON, SOAP, etc. - SMT32 is fast enough to parse this.
Option 2 - binary protocol - this is more rational for working with the controller. (but if you have a large performance margin, then there is no point in bothering with this).