很好的P2P参考示例，P2P网络流行的发起者；PeerCast是一个健壮的网络，因为不存在中心服务器，每个用户可以是客户，也可是服务器，也可以是流的广播者。-P2P good reference example, P2P networks popular initiator PeerCast is a robust network because there is no central server, each user can be a customer, but also servers,