Protocol Design,

I am very new to designing a protocol so I am not sure how to start this problem.

I need to design a air conditioner application protocol which controls the temperature of home using internet connection. This protocol should be a client server internet protocol in which the computer is the client and the air conditioner is the server. This protocol should first, read the current temperature and then set the heater's desired temperature. For example, the message to the heater would be setting the temperature to 75. Also, the protocol must use TCP to make the connection.

so the first part would be just giving some general descriptions about the messages. Then I need to design the actual messages such as temperatures values. At this part I need to say how many messages are needed to be sent back and force between the client and server and what they actually do.

Then I need to generate specifications of the messages such as temperature, IP address of the server. something like figure below:

probably the messages that need to be sent between the client and server would be easy to understand. But I am not sure how to generate the messages and put them in that figure.

Thank you!

method sp URL sp version cr If request header field name value cr If line header lines header field name value cr f cr If entity body body