P2P tutorial (ESEC 2001) How much P2P is involved? P2P user P2P P2P interaction application information management eBay yes no no Napster yes yes no Gnutella, yes yes yes Freenet 2001 Karl Aberer,Manfred Hauswirth ESEC/FSE 2001 9 P2P Cooperation Models 。Centralized model - global index held by a central authority (single point of failure) -direct contact between requestors and providers Example:Napster ·Decentralized model Examples:Freenet,Gnutella no global index,no central coordination,global behavior emerges from local interactions,etc. direct contact between requestors and providers(Gnutella)or mediated by a chain of intermediaries (Freenet) ·Hierarchical model introduction of "super-peers" -mix of centralized and decentralized model Example:DNS 2001 Karl Aberer,Manfred Hauswirth ESEC/FSE 2001 10 (c)2001 Karl Aberer,Manfred Hauswirth 5P2P tutorial (ESEC 2001) (c) 2001 Karl Aberer, Manfred Hauswirth 5 © 2001 Karl Aberer, Manfred Hauswirth ESEC/FSE 2001 9 How much P2P is involved? Gnutella, yes yes yes Freenet Napster yes yes no eBay yes no no P2P information management P2P application P2P user interaction © 2001 Karl Aberer, Manfred Hauswirth ESEC/FSE 2001 10 P2P Cooperation Models • Centralized model – global index held by a central authority (single point of failure) – direct contact between requestors and providers – Example: Napster • Decentralized model – Examples: Freenet, Gnutella – no global index, no central coordination, global behavior emerges from local interactions, etc. – direct contact between requestors and providers (Gnutella) or mediated by a chain of intermediaries (Freenet) • Hierarchical model – introduction of “super-peers” – mix of centralized and decentralized model – Example: DNS