Abstract — Over the Internet today, computing and communications environments are significantly more complex and chaotic than classical distributed systems, lacking any centralized organization or hierarchical control. There has been much interest in emerging Peer-to-Peer (P2P) network overlays because they provide a good substrate for creating large-scale data sharing, content distribution and application-level multicast applications. These P2P networks try to provide a long list of features such as: selection of nearby peers, redundant storage, efficient search/location of data items, data permanence or guarantees, hierarchical naming, trust and authentication, and, anonymity. P2P networks potentially offer an efficient routing architecture that is self-organizing, massively scalable, and robust in the wide-area, combining fault tolerance, load balancing and explicit notion of locality. In this paper, we present a survey and comparison of various Structured and Unstructured P2P networks. We categorize the various schemes into these two groups in the design spectrum and discuss the application-level network performance of each group.

An efficient name resolution scheme is the cornerstone of any peer-to-peer network. The foundation of an efficient name resolution scheme is a dynamic network topology that determines the neighbor relationships to be maintained by the nodes in the network. The name resolution scheme proposed by Plaxton, Rajaraman, and Richa, which we hereafter refer to as the PRR scheme, is a scalable scheme that also provides provable locality properties on a certain class of growth-restricted metric spaces. On arbitrary metric spaces, however, some performance bounds of PRR are significantly weakened. In this paper, we define a class of network topologies called hyperdelta networks and observe that the PRR topology may be viewed as a random hyperdelta network. We then propose SPRR (simplified PRR), a variant of the PRR scheme that performs well on arbitrary metric spaces. SPRR imposes additional constraints on PRR neighbor selection by placing the nodes on a cycle. Although SPRR does not provide as strong locality properties as PRR, it exploits locality heuristically yet effectively. Finally, a significant level of fault tolerance can be achieved in SPRR without adding much complexity.

Abstract. In this paper, we first propose a novel Public License Infrastructure (PLI) that uses cryptographic threshold secret sharing schemes to provide decentralized public license services for the Digital Rights Management (DRM). This distributed PLI replaces the centralized license server in a conventional DRM system. PLI offers many advantages such as intrusion and fault tolerance, flexibility, scalability, reliability, high availability. We then propose a PLI-based DRM system to provide content protection and digital rights management for users of Peer-to-Peer (P2P) networks. This DRM system is especially useful for small content providers such as peers in a P2P network who cannot afford the conventional server/client based DRM system and traditional distribution channels.

Abstract — Skyline queries have received a lot of attention from database and information retrieval research communities. A skyline query returns a set of data objects that is not dominated by any other data objects in a given dataset. However, most of existing studies focus on skyline query processing in centralized systems. Only recently, skyline queries are considered in a distributed computing environment. Acknowledging the trend toward peer-to-peer (P2P) systems in distributed computing, we examine the problem of skyline query processing in P2P systems and propose innovative solutions. We exploit the data semantic embedded in semantically structured P2P overlay networks to efficiently prune search space, without compromising the quality of query result. In addition, we propose approximate algorithms to support skyline queries where exact answers are too costly to obtain. These approximate algorithms produce high quality answers using heuristics based on local semantics of peer nodes. Extensive experiments validate that our algorithms provides high efficiency and scalability to skyline query processing in P2P systems. I.