Editorial: Peer-to-Peer networking and applications, Volume 3, Issue 4

In this issue of the Peer-to-Peer Networking and Applications, after the survey on Peer-to-Peer Session Initiation Protocol based Communication Systems, six original research works are presented to study the interesting and important problems on document preservation, video on demand, common standard model and development platform, service oriented architectures, and semantic networks. Due to the simplicity, extensibility and flexibility, more and more applications are being developed on the top of Session Initiation Protocol (SIP). To facilitate robustness and fault tolerance, several P2P-based SIP solutions have been proposed. In the survey paper, “A Survey on Peer-to-Peer SIP based Communication Systems”, Zheng and Oleshchuk thoroughly investigate the development on P2P-based SIP by detailing P2PSIP requirements, Chord-based overlays, session initiation services, NAT traversal, and message routing. They also introduce different security problems in P2PSIP and provide possible solutions. Computer and Internet technologies have been pushing our daily lives from paper-based documents to digital documents. In addition to contacts, photographs, movies, music, conversations, and Web-sites, publishers and libraries are also moving towards digital documents. Thus, long-term preservation of these digital documents are becoming crucial. A Peer-to-Peer