java client server example
server should be able to handle more than 1 client.
client has an id that is defined in the client (e.g. client id 12)
client has a thread that every 15 seconds sends the same message "message from client 12"
after client has established server listens to the client and prints out messages from the client.
when server looses connection to client print out
connection to client 12 lost.
client can log off when it sends message "exit".
server prints out "client 12 has logged off"