peer-to-peer

New entry in Digiplay games research bibliography:

Scalability is a critical issue for Massively Multiplayer Online Role Playing Games (MMORPG). To address the scalability drawbacks of current central server model, we present a scenario to support MMORPG through Pastry, a structured peer-to-peer overlay. In order to closely reflect an advanced MMORPG configuration, the scenario considers bandwidth and latency constraints required by the games based on actual MMORPG traffic pattern. A simulation model is developed to evaluate the performance of Pastry in supporting such a scenario. Results show that Pastry performs well in distributing node stress. However, there is a bottleneck in terms of upstream bandwidth usage, which can be removed by low-cost algorithms. Results also show that using Scribe multicast tree built on top of Pastry to disseminate game traffic is an effective way to save bandwidth usage. In addition, Scribe multicast tree scales well in supporting the scenario with respect to the tree length. When a tree size increases five times, the length of the tree only increases less than two levels.

New entry in Digiplay games research bibliography:

MMOG are very large distributed applications, sharing very large states, and supporting communication between potentially thousands of player nodes. Despite the development of many solutions to define suitable architecture and communication protocol, and enabling efficient deployment of these types of applications, many issues remains which still require a solution. In this paper we discuss MMOG deployed over a Peer-to-Peer architecture, supporting a distributed model of systems with shared state and we address issues related to scalability, interest management and communication. We identify an efficient partitioning and distribution of the shared state as an important aspect in such models and propose a hierarchical multi-level interest management algorithm which enables contextual communication between peers. Experiments have been carried out and show the performance of the approach.

New entry in Digiplay games research bibliography:

Large scale distributed virtual environments (DVEs) have become a major trend in distributed applications, mainly due to the enormous popularity of multi-player online games in the entertainment industry. Since architectures based on networked servers seem to be not scalable enough to support massively multi-player applications, peer-to-peer (P2P) architectures have been proposed as an efficient and truly scalable solution for this kind of systems. However, in order to design efficient DVEs based on peer-to-peer architectures these systems must be characterized, measuring the impact of different client behaviors on system performance. This paper presents the experimental characterization of peer-to-peer distributed virtual environments in regard to well-known performance metrics in distributed systems. Characterization results show that system saturation is inherently avoided due to the peerto-peer scheme, as it could be expected. Also, these results show that the saturation of a given client exclusively has an effect on the surrounding clients in the virtual world, having no noticeable effect at all on the rest of avatars. Finally, the characterization results show that the response time offered to client computers greatly depends on the number of new connections that these clients have to make when new neighbors appear in the virtual world. These results can be used as the basis for an efficient design of peer-to-peer DVE systems.

New entry in Digiplay games research bibliography:

While multi-player online games are very successful, their fast deployment suffers from their server-based architecture. Indeed, servers both limit the scalability of the games and increase deployment costs. However, they make it easier to control the game (e.g. by preventing cheating and providing support for billing). Peer-to-peer, i.e. transfer of the game functions on each each player's machine, is an attractive communication model for online gaming. We investigate here the challenges of peer-to-peer gaming, hoping that this discussion will generate a broader interest in the research community.

New entry in Digiplay games research bibliography:

Digital products can be copied at almost no cost and are subject to non-commercial copying by final consumers. Because the copy of a copy typically does not deteriorate in quality, copies can become available on a large scale basis - this can be illustrated by the surge of file-sharing networks. In this paper we provide a critical overview of the theoretical literature that addresses the economic consequences of end-user copying. We analyze basic models of piracy, models with indirect appropriation, models with network effects, and models with asymmetric information. We discuss the applicability of the different modeling strategies to a number of industries such as software, video and computer games, music, and movies.

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