Client : 
A simple TCP client program shows connect / send / receive / disconnect functions.

Client_reconnect : 
A simple TCP client program shows connect / send / receive / disconnect functions.
The program always close and reconnect the connection after send/receive operations.

Server1:
A simple TCP echo server supports a single client connection.
The last connection is always the operating one.
Read/Write to the server handle is redirected to the last connected client connection.

ServerM:
A simple TCP echo server supports multiple client connections.
Each client connection has it's own handle.
Server can then read / write to these connections by these handles.
Callback functions are used for supporting multiple connections.