Hi everyone, I want to write a server,it works just like this: 1.client will connect to the server,maybe with some auth information. 2.the server verify the client,if it's ok,accept the connection. 3.the client starts to sent some binary data to server buffer by buffer ,the server will use it to calculate in real time. 4.when all the data is sent,the client will tell the server no data any more. 5.the server gets a result from the data,and sends the result to the client(the client is ASCII code) 6.server shuts down the connection. first,I want to know which protocol I should use?the LineReceiver is ok for this? second,I know the LineReceiver protocol can switch between line mode and row mode,I think I will use line mode to send the control command,and use raw mode to sent the data,but how the client can inform the server which mode should use?because sometimes the data which is received in raw mode is exactly a legal command,but it is just only a part of the data. third,I don't know very much about how to send the binary data,I heard I should use struct modul,is it right? any hint is helpful,please just give me a direction,I hope my question will not take too much time to answer,thanks a lot. Regards Chris