FIRST send 'HTTP-like' command ?

--Premise-- (1) I want to send a command from a server on AWS to a machine tool connected to the company's LAN (within the Shimowada factory). (Automatic control) (2) There is a machine tool command sending server (RS232C (BSC procedure), Ether (sending commands without HTTP headers to machine tools) interfaces on the company LAN. (3) When the above command sending server receives an HTTP-like command in AWS (I think it's easy to implement), it sends the command to the machine tool via RS232C or Ether. ーーQuestionー In the above, the AWS server is expressed as "HTTP-like" to prevent primitive implementations such as sockets. However, I think that normal HTTP always sends a request from the client side and returns a response from the server side for the first time. Is there an implementation method (method) that is easy to implement and that commands are issued first from the server? I don't want to use sockets as much as possible.