1)handle_connect: is called when a connection is successfully established.
2)handle_expt :is called when a connection fails.
3)handle_accept :is called when a connection request is made to a listening socket. The callback should call the accept method to get the client socket.
4)handle_read:is called when there is data waiting to be read from the socket. The callback should call the recv method to get the data.
5)handle_write:is called when data can be written to the socket. Use the send method to write data.
6)handle_close: is called when the socket is closed or reset.
7)handle_error(type, value, traceback): is called if a Python error occurs in any of the other callbacks. The default implementation prints an abbreviated traceback to sys.stdout.