Design Issues for Peer-to-Peer Massively Multiplayer Online Games.

Massively Multiplayer Online Games (MMOGs) are increasing in both popularity and scale, and while classical Client/Server (C/S) architectures convey some benefits, they suffer from significant technical and commercial drawbacks. This realisation has sparked intensive research interest in adapting MMOGs to Peer-to-Peer (P2P) architectures. This paper articulates a comprehensive set of six design issues to be addressed by P2P MMOGs, namely Interest Management (IM), game event dissemination, Non-Player Character (NPC) host allocation, game state persistency, cheating mitigation and incentive mechanisms. Design alternatives for each issue are systematically compared, and their interrelationships discussed. We further evaluate how well representative P2P MMOG architectures fulfil the design criteria

Solving key design issues for massively multiplayer online games on peer-to-peer architectures

Massively Multiplayer Online Games (MMOGs) are increasing in both popularity and scale on the Internet and are predominantly implemented by Client/Server architectures. While such a classical approach to distributed system design offers many benefits, it suffers from significant technical and commercial drawbacks, primarily reliability and scalability costs. This realisation has sparked recent research interest in adapting MMOGs to Peer-to-Peer (P2P) architectures. This thesis identifies six key design issues to be addressed by P2P MMOGs, namely interest management, event dissemination, task sharing, state persistency, cheating mitigation, and incentive mechanisms. Design alternatives for each issue are systematically compared, and their interrelationships discussed. How well representative P2P MMOG architectures fulfil the design criteria is also evaluated. It is argued that although P2P MMOG architectures are developing rapidly, their support for task sharing and incentive mechanisms still need to be improved. The design of a novel framework for P2P MMOGs, Mediator, is presented. It employs a self-organising super-peer network over a P2P overlay infrastructure, and addresses the six design issues in an integrated system. The Mediator framework is extensible, as it supports flexible policy plug-ins and can accommodate the introduction of new superpeer roles. Key components of this framework have been implemented and evaluated with a simulated P2P MMOG. As the Mediator framework relies on super-peers for computational and administrative tasks, membership management is crucial, e.g. to allow the system to recover from super-peer failures. A new technology for this, namely Membership-Aware Multicast with Bushiness Optimisation (MAMBO), has been designed, implemented and evaluated. It reuses the communication structure of a tree-based application-level multicast to track group membership efficiently. Evaluation of a demonstration application shows i that MAMBO is able to quickly detect and handle peers joining and leaving. Compared to a conventional supervision architecture, MAMBO is more scalable, and yet incurs less communication overheads. Besides MMOGs, MAMBO is suitable for other P2P applications, such as collaborative computing and multimedia streaming. This thesis also presents the design, implementation and evaluation of a novel task mapping infrastructure for heterogeneous P2P environments, Deadline-Driven Auctions (DDA). DDA is primarily designed to support NPC host allocation in P2P MMOGs, and specifically in the Mediator framework. However, it can also support the sharing of computational and interactive tasks with various deadlines in general P2P applications. Experimental and analytical results demonstrate that DDA efficiently allocates computing resources for large numbers of real-time NPC tasks in a simulated P2P MMOG with approximately 1000 players. Furthermore, DDA supports gaming interactivity by keeping the communication latency among NPC hosts and ordinary players low. It also supports flexible matchmaking policies, and can motivate application participants to contribute resources to the system

A novel scalable hybrid architecture for MMOG

We present a novel MMOG Hybrid P2P architecture and detail its key components, topology and protocols. We highlight the main components which lie at the heart of the proposed solution, and their roles, and describe the methods of tackling the key scenarios which are faced by the architecture during gameplay. For each role, we discuss the interactions that exist between them and describe the protocols that will be used for inter-role communication to perform the atomic actions necessary for maintaining the consistency and responsiveness of an MMOG such as peer addition, peer removal, group transfer, object change persistency and many more. We conclude the chapter with a comparison of the architecture against several existing P2P MMOG frameworks, discussing the differences which exist between them and how the novel Hybrid-P2P architecture we propose aims to address their flaws

Comparação de uma versão Cliente-Servidor com uma versão Peer-to-Peer para o jogo WebRun

O negócio dos jogos online está em constante expansão. Se pensarmos que neste preciso momento se encontram ligados milhões de jogadores a um qualquer jogo online, rapidamente percebemos a dimensão e potencialidade deste mercado. São jogos cada vez mais complexos e elaborados, de maneira fidelizar os jogadores atuais, mantendo-os motivados, e a angariar potenciais jogadores. Essa motivação tem a ver não só com a atratividade do jogo mas também com a qualidade de serviço que o jogo oferece. A maioria dos jogos online segue um modelo cliente-servidor, uma arquitetura que facilita o desenvolvimento e o controlo do jogo, nomeadamente em termos de evitar a utilização indevida por jogadores mal-intencionados. Esta arquitetura tem, no entanto, problemas em termos de escalabilidade. Com o aumento do número de utilizadores, a qualidade do serviço diminui do ponto de vista dos jogadores. Nesta dissertação propomos como alternativa a utilização de uma arquitetura peer-to-peer para um jogo que permite promover a atividade física e que inicialmente foi desenvolvido como cliente-servidor: o jogo WebRun. Apresenta-se um estudo do desempenho das duas versões do jogo quando o número de jogadores aumenta. Os resultados obtidos mostram que a arquitetura peer-to-peer permite aumentar significativamente a escalabilidade do jogo, sendo uma alternativa promissora para áreas em que o problema da fraude no jogo não seja crítico.The business of online gaming is constantly expanding. If we think that in this precise moment there are millions of players linked to any online game, we quickly realized the power of this market. These games are more and more complex and have elaborated sceneries, in order to keep motivated the current players and captivate new potential players. This motivation has to do with not only the attractiveness of the game but also with the quality of service that the game offers. Most online games follow a Client/Server architecture that facilitates the development and control of the game, for example, in terms of preventing improper use by malicious players. This architecture has, however, problems in terms of scalability. When the number of users increases, decreases the quality of service from the viewpoint of the players. In this thesis we propose as alternative the use of Peer-to-Peer architecture for a game that promotes physical activity and that was initially developed as Client/Server: the WebRun game. It presents a study of the performance of two versions of the game when the number of players increases. The results show that the Peer-to-Peer architecture significantly increases the scalability of the game, being a promising alternative for areas where the fraud problem is not critical

Applying Supernode Architecture for Scalable Multiplayer Computer Game

Süsteemi skaleeritavus, kiire vastamise aeg ja madal hinnatase on tähtsad atribuudid, mida tuleb arvesse võtta suurte multimängijatega online mitmikmängude loomisel. Sellistes süsteemides mängib suurt rolli arhitektuur. Partnervõrkude arhitektuuridel on madalad hinnad ning need suudavad saavutada järk-järgulise kasvu tänu nende hajususele ja koostööle. Peale selle suudavad nad kiirelt reageerida tänu otseühendustele mängijate vahel. Samas esineb selliste arhitektuuridega mitmeid probleeme. Selles lõputöös uuritakse olemasolevaid partnervõrkude lahendusi suurtele multimängijatega online olevatele mängudele. Veel uurib see lõputöö kahte hübriidarhitektuuri - esimeses on kasutatud supernode punkte koos keskse ühenduspunktiga ning teises on kasutatud keskset võrguharu ühenduspunkti ilma keskse ühenduspunktita. Lisaks sellele esitab see lõputöö lahenduse supernodemultimängijatega online mängudele, mis põhinevad multiedastuse põhimõttel.Selleks, et tulevikus analüüse läbi viia, on kogu süsteem implementeeritud simulatsiooniga.Scalability, fast response time and low cost are of utmost importance in designing a successful massively multiplayer online game. The underlying architecture plays an important role in meeting these conditions. Peer-to-peer architectures, have low infrastructure costs and can achieve high scalability, due to their distributed and collaborative nature. They can also achieve fast response times by creating direct connections between players. However, these architectures face many challenges.Therefore, the paper investigates existing peer to peer architecture solutions for a massively multiplayer online games. The study examines two hybrid architectures. In the first one, a supernode approach is used with a central server. In the contrast in the second one, there is no central server and pure peer to peer architecture is deployed. Moreover, the thesis proposes a solution based on multicast peer discovery and supernodes for a massively multiplayer online game. Also, all system is covered with simulation, that provides results for future analysing

Secure referee selection for fair and responsive peer-to-peer gaming

Peer-to-Peer (P2P) architectures for Massively Multiplayer Online Games (MMOG) provide better scalability than Client/Server (C/S); however, they increase the possibility of cheating. Recently proposed P2P protocols use trusted referees that simulate/validate the game to provide security equivalent to C/S. When selecting referees from untrusted peers, selecting non-colluding referees becomes critical. Further, referees should be selected such that the range and length of delays to players is minimised (maximising game fairness and responsiveness). In this paper we formally define the referee selection problem and propose two secure referee selection algorithms, SRS-1 and SRS-2, to solve it. Both algorithms ensure the probability of corrupt referees controlling a zone/region is below a predefined limit, while attempting to maximise responsiveness and fairness. The trade-off between responsiveness and fairness is adjustable for both algorithms. Simulations of three different scenarios show the effectiveness of our algorithms

Virtual Net: a Decentralized Architecture for Interaction in Mobile Virtual Worlds

With the development of mobile technology, mobile virtual worlds have attracted massive users. To improve scalability, a peer-to-peer virtual world provides the solution to accommodate more users without increasing hardware investment. In mobile settings, however, existing P2P solutions are not applicable due to the unreliability of mobile devices and the instability of mobile networks. To address the issue, a novel infrastructure model, called Virtual Net, is proposed to provide fault-tolerance in managing user content and object state. In this paper, the key problem, namely object state update, is resolved to maintain state consistency and high interaction responsiveness. This work is important in implementing a scalable mobile virtual world

Efficient Peer-to-Peer Content Sharing for Learning in Virtual Worlds

Virtual world technologies provide new and immersive space for learning, training, and education. They are enabled by the content creation and content sharing function for allowing users to create and interoperate various learning objects. Unfortunately, virtual world content sharing based on persistent virtual world content storage, to the best of our knowledge, does not exist. In this paper, we address this problem by proposing a content sharing scheme based on Virtual Net, a virtual world persistency framework. For efficient content retrieval, three strategies have been proposed to reduce communication overhead and content load delay.By integrating these strategies, a virtual world content search and retrieval algorithm has been devised. The experiment results verify the effectiveness of the algorithm

Dynamic Load Balancing for Massively Multiplayer Online Games

In recent years, there has been an important growth of online gaming. Today’s Massively Multiplayer Online Games (MMOGs) can contain millions of synchronous players scattered across the world and participating with each other within a single shared game. Traditional Client/Server architectures of MMOGs exhibit different problems in scalability, reliability, and latency, as well as the cost of adding new servers when demand is too high. P2P architecture provides considerable support for scalability of MMOGs. It also achieves good response times by supporting direct connections between players. This thesis proposes a novel hybrid Peer-to-Peer architecture for MMOGs and a new dynamic load balancing for massively multiplayer online games (MMOGs) based this hybrid Peer-to-Peer architecture. We have divided the game world space into several regions. Each region in the game world space is controlled and managed by using both a super-peer and a clone-super-peer. The region's super-peer is responsible for distributing the game update among the players inside the region, as well as managing the game communications between the players. However, the clone-super-peer is responsible for controlling the players' migration from one region to another, in addition to be the super-peer of the region when the super-peer leaves the game. In this thesis, we have designed and simulated a static and dynamic Area of Interest Management (AoIM) for MMOGs based on both architectures hybrid P2P and client-server with the possibility of players to move from one region to another. In this thesis also, we have designed and evaluated the static and dynamic load balancing for MMOGs based on hybrid P2P architecture. We have used OPNET Modeler 18.0 to simulate and evaluate the proposed system, especially standard applications, custom applications, TDMA and RX Group. Our dynamic load balancer is responsible for distributing the load among the regions in the game world space. The position of the load balancer is located between the game server and the regions. The results, following extensive experiments, show that low delay and higher traffic communication can be achieved using both of hybrid P2P architecture, static and dynamic AoIM, dynamic load balancing for MMOGs based on hybrid P2P system