how compose in the top of the same machine since is a client is also serve

hi all~
the beginner java network program, please ask how the ability is in the same pc top since is a client is also server of the network programMainly is an ability, each other delivers to seal a pack each other, whether can have simple example can make reference to??

I'm sorry but I don't think I understand what you mean, do you mean that the server and the client software will run on the same machine?

// Json

hi ~
yes~maybe a client and a server program run in the same pc .
how to send udp packet to other pc inorder to compute packet loss rate ?