some doubt about client/server concepts

[Luigi 33]

Hi! 8D

I am studying the last period of my course and the school require a work conclusion curse (here called TCC), I writing a little software to manage a laboratory, control the machines with a client/server.

At this time, all communication between client and server is a uncoded messages.

If the client nedeed login, it send the username and password in a simple text (TCPSEND only) and waitin asnwer's server.

Everything is very simple, but it's work (sometimes bugs is happend).

I have some questions...

a] someone can sugest to me a simple method to code the conversation between client and server?

b] in the moment I see necessity to write tree modules:

1.stand alone server running in background as service (whitout interface administrative)

2.client

3.administrative interface

Question: this is a good idea? Or peoples writing the server with a administrative interface togheter?

c] I have no good idea to check if clients is connect or not... perhaps in periodic time send some specific command waiting a reply, if not have answer, put this host like offline. This is a good idea? This is not overload a lan trafic with status message check?

Thanks