Decentralized peer-to-peer systems fit well as the underlying infrastructure for IP-telephony, as they provide the scalability for a large number of participants, and are able to handle the limited storage and bandwidth capabilities on the clients. We studied a commercial peer-to-peer-based decentralized communication platform supporting video communication, voice communication, instant messaging, et cetera. One of the requirements of the communication platform is the implementation of a user directory, allowing users to search for other participants. In this chapter, we present the Extended Prefix Hash Tree algorithm that enables the implementation of a user directory on top of the peer-to-peer communication platform in a fully decentralized way. We evaluate the performance of the algorithm with a real-world phone book. The results can be transferred to other scenarios where support for range queries is needed in combination with the decentralization, self-organization, and resilience of an underlying peer-to-peer infrastructure.
A Dynamic Tree Algorithm for Peer-to-Peer Ridesharing Matching
