Login Query
The login or identification query informs the server of the type of node initiating the connection, whether it's a client or an mcu.
This query poses an exception from the 4-byte code structure, though it still follows the overall query structure. Instead of using said code, it relies on two constant sequences Client_here and NodeMCU_here, which represent the client node and mcu nodes respectively.
This query has a different behaviour depending on whether it was successful or not. When it succeeds, the server will send no reponse and, on failure, the server will reply with a control query containing an error code identifying the error. The possible error codes that may be returned by the server are:
_NACK_InvalidQuery(uint8_t c=255) → If the query format is invalid: contains null-bytes, invalid header or tail sequences, or the query does not follow the structure for the client or mcu login queries.
Client Login Query
The client login query is very straightfoward: The client sends the login query and, assuming there's no unexpected/unknown errors on server-side, the client will be logged to the server successfully. Otherwise, a negative control query will be returned, and the connection will be closed.
The login query is a constant sequence of characters with the form: !s-Client_here-e!.
MCU Login Query
On the other hand, the mcu login query is a little bit more complex. The query will follow a structure similar to the client one, using the constant sequence !s-NodeMCU_here-[info]-e! but with an additional information field, [info], added to the message. This additional field will contain information about the mcu, such as the unique id or name, used to identify the mcu; the number of servos, which indicates how many servos the mcu has; and either a fixed byte value (uint8_t c=187), if the mcu is of the type DumbMCU; or the current position of each of the mcu servos, if the mcu is of the type SmartMCU.
[MCU_UNIQUE_NAME]→ The unique id used to identify the mcu (char[]).[SERVO_COUNT]→ A singleuint8_tindicating how many servos the mcu has. Since this number cannot be zero, it does not need any offset applied.[SERVOPOS(i)]→ The position of each mcu servo (as auint8_t), with a dash-between each of them, and ordered by ascending servo ID. Since this value can be zero (0-179 range), by protocol it needs to be offset by +1.
[MCU_UNIQUE_NAME]→ The unique id used to identify the mcu (char[]).[SERVO_COUNT]→ A singleuint8_tindicating how many servos the mcu has. Since this number cannot be zero, it does not need any offset applied.[187]→ The byteuint8_t b=187. Indicates the server that the mcu is of the type DumbMCU.
