CFSOCKET sending data to server at regular time interval

I've never used CFSOCKET, however I've used 'raw' sockets a lot (on both unix and windows) and at a quick glance, that looks like a thin cocoa wrapper for the 'raw' sockets.  If you have a client and he can only send one message, it's probably because the server is replying and closing the socket.  So you'll have to keep opening it again.

Some internet protocols (eg HTTP 1.0) are stateless and the server closes the connection after every response.

If you're still stuck, could you post some simple code and I'll look at it for you.