Abstract
Peer-to-Peer computing is a model consisting of cooperating distributed processing units terms peers. Characteristics of this computing model include lack of centralized control and hierarchical organization of the peers. Instead, peers take on roles of client/server, provider/requester or spotter (router) as needed. Peers need to be equipped with hardware and software capabilities that provide these functions. Peer-to-Peer computing is a relatively recent and emerging computing model. One among the interesting research issues of this computing model is the communication requirements induced by Peer-to-Peer applications. Peer-to-Peer applications can be described in terms of a service layer model that abstracts the required services needed to perform all aspects of that application together with a physical layer that abstracts the required physical components involved in the services. This paper proposes the two respective models of Service Model and Physical Model to provide these abstractions in a comprehensive and cohesive manner. The main point of emphasis is the two-layer modeling of communication requirements induced by Peer-to-Peer applications.