Satisfiability and trustworthiness of acquaintances in peer-to-peer overlay networks

Various types of applications access to objects distributed in peer-to-peer (P2P) overlay networks. Even if the locations of target objects are detected by some algorithms like flooding and distributed hash table (DHT) ones, applications cannot manipulate the target objects without access requests. It is critical to discover which peer can manipulate an object in which method, i.e. only a peer with an access right is allowed to manipulate an object. Hence, the application rather has to find target peers which can manipulate a target object than detecting the location of a target object. Due to the scalability and variety of peers, it is difficult, possibly impossible to maintain a centralized directory showing in which peer each object is distributed. An acquaintance peer of a peer p is a peer whose service the peer p knows and with which the peer p can directly communicate. We discuss types of acquaintance relations of peers with respect to what objects each peer holds, is allowed to manipulate, and can grant access rights on. Acquaintance peers of a peer may notify the peer of different information on target peers due to communication and propagation delay. Here, it is critical to discuss how much a peer trusts each acquaintance peer. We first define the satisfiability, i.e. how much a peer is satisfied by issuing an access request to another peer. For example, if a peer $p_{\!j}$ locally manipulates a target object o and sends a response, a peer p i is mostly satisfied. On the other hand, if $p_{\!j}$ has to ask another peer to manipulate the object o, p i is less satisfied. We define the trustworthiness of an acquaintance peer of a peer from the satisfiability and the ranking factor.