Research On P2P Overlay Architecture For MMOG

MMOG (Massively Multiplayer Online Games) is a typical class of distributed system that depends on the network as the communication manner. It has advantages of the bi-direction communication, high-speed, free of the limited space etc, and the qualities for the interaction, the simulation and the competition are improved tremendously. It has attracted more and more scholars, corporations and players in recent years. Currently, most of the commercial MMOGs are supported by client-server architecture, where the server keeps all shared information and coordinate communication among users. Most of the computation work is executed at the server, and client is only a terminal system in charge of receiving order. Therefore, the scalability is inherently restricted by the architecture, which causes the system can't support massively players. To solve the problem, scalability is achieved by employing server clusters. The servers can either be connected by LANs, or form a computing grid. Although this architecture scales with the number of players, it lacks flexibility and the server has to be over-provisioned to handle peak loads.In comparison with traditional C/S computing model, P2P weakens or even eliminates the functionality of central servers. It can fully take advantage of the resource on the hosts distributed in the network. MMOG is a natural application for peer-to-peer overlay. This dissertation takes advantage of the self-organizing characteristic of P2P overlays to create a system that dynamically scales up and down with the number of players. One notable difference between P2P MMOG and other P2P applications such as file-sharing is that the problem of content search is greatly simplified: as each node's AOI (Area of Interest) is limited, the desired content is localized and easily identified as the messages generated by other nodes within the AOI. This differs from file-sharing where the desired content may potentially be on any node. Content search in P2P, therefore, becomes a neighbor discovery problem in the MMOG context. Therefore, the existing scheme can not support MMOG appropriately, and how to design a scalable and adaptive P2P overlay architecture for MMOG becomes a hotspot problem in recent years.In view of the particular local requirement and scalable requirement of MMOG, this dissertation analyses the schemes of P2P overlay architecture for MMOG from home and abroad and mainly finishes the following works:1 Propose a scalable P2P overlay architecture for MMOGConsidering system responsiveness and connectivity, this dissertation proposes a P2P overlay architecture for P2P MMOG—SPOAR (scalable P2P overlay architecture). On the basis of structured P2P overlay architecture, this dissertation adopts the unstructured P2P scheme based on MANET to maintenance neighbor topology in the game world and perform neighbor discovery.2 Propose a topology consistency algorithm and fault-tolerance mechanism for SPOARBecause players join and leave the game frequently, MMOG is more dynamic than other P2P applications such as file-sharing. Aimed at the dynamic topology management of SPOAR overlay architecture, this dissertation proposes a topology consistency algorithm and fault-tolerance mechanism.3 Propose a distributed event delivery mechanismThis dissertation analyses the object interactions and the events produced during the interaction among them in the online game, and propose a distributed event delivery mechanism to achieve game states consistency consequently.The simulation results show that SPOAR overlay architecture achieves a balance between global connectivity and local communication timeliness. Moreover, the distributed event delivery algorithm based on SPOAR can obviously decrease the load of coordinator and gain a greater improvement than other corresponding algorithms on reducing message redundancy.