UC Riverside

User-interactive applications are evolving in both popularity and scale on the Internet, ranging from simple le-sharing to more demanding applications such as collaborate workspace, massive multi-player online games (MMOGs). These applications are traditionally implemented by Client/Server architectures, which suer from signicant

technical and commercial drawbacks, primarily high-maintenance cost and limited scalability. To overcome these drawbacks, this dissertation presents a Peer-to-Peer (P2P) approach to support large-scale interactive applications.

This dissertation addresses two key design issues for P2P systems to achieve scalability and high performance. The rst issue is to provide incentives for users so that P2P systems can aggregate free resources from unreliable users. The second issue is to design consistency maintenance schemes so that P2P systems can provide reliable

services to meet the application requirements by using free resources from unreliable users.

For the rst issue, this dissertation starts with providing a budget based incentive search service, called BuSIS [105], for eciently locating service providers in P2P systems. Then, an incentive trading model, called FairTrade [102], is presented for P2P users to exchange service with each other. Personal currency model is employed in FairTrade to simulate users to contribute to the P2P community in exchange of desired services. To cope with highly dynamic nature of P2P systems, an enhanced incentive trading model, called CoBank [101], is presented to reduce maintenance overhead at each user and improve robustness against malicious attacks. Cooperative banking strategy is

used in CoBank to further distribute the maintenance workload.

For the second issue, this dissertation begins with providing a consistency maintenance framework, called BCoM [104, 100], balancing between consistency strictness, availability and performance for various P2P interactive applications with heterogenous

resource constraints. Then, this dissertation presents a real-time consistency maintenance P2P system, called PPAct [103], for interactive applications such as MMOGs. View discovery and update dissemination are decoupled in PPAct to mitigate the hot spot problem and ensure consistency maintenance under stringent latency constraints.