Hybrid of client-server and P2P Napster File transfer p2p File search centralized Peers register content at central server Peers query same central server to locate content Instant messaging Chatting between two users is P2P Presence detection/location centralized User registers its ip address with central server when it comes online User contacts central server to find IP addresses of buddies 哈工大计算机学院李全龙 Network Application Development P2P Application Development 10哈工大计算机学院 李全龙 Network Application Development P2P Application Development 10 Hybrid of client-server and P2P Napster „ File transfer P2P „ File search centralized: „ Peers register content at central server „ Peers query same central server to locate content Instant messaging „ Chatting between two users is P2P „ Presence detection/location centralized: „ User registers its IP address with central server when it comes online „ User contacts central server to find IP addresses of buddies