CoreGRID Newsletter - Enabling Scalable Online Game Services using the Grid

Enabling Scalable Online Game Services using the Grid
Multiplayer online games have recently become a very popular class of distributed applications with an enormous amount of running Internet-based game sessions. The new concept of Massively Multiplayer Online Games (MMOG) with thousands of users in a single game session requires very scalable game architectures. A lot of computing resources are required to actually run such large scale game sessions. The Grid poses a promising approach to provide computation power for next generation online entertainment.




1. Scaling Online Games to the Massively Multiplayer Realm
Considering the number of users in a single game session, two different classes of games are currently played over the Internet: Multi-server Massively Multiplayer Online Role Playing Games (MMORPG) already run with thousands of users in a persistent world. On the other hand, single-server games like First Person Shooter (FPS) and Real-time Strategy (RTS) games only allow game sessions with less than 100 participating players.
The scalability of an online game is determined by the underlying network architecture. Whereas MMORPG partition the huge game world in several independent regions and assign their processing to several servers, FPS and RTS game environments usually can not be partitioned due to their limited size. In recent work, the group of Prof. Gorlatch at the University of Münster developed a novel proxy-server architecture [1] which is designated especially for FPS and RTS games. The proxy server approach replicates the game state at several servers and outperforms the usually used single-server and peer-to-peer concepts in terms of scalability, as we found out by describing the usage of the resources computation power and communication bandwidth in an analytical Game Scalability Model [2]. This way, several hundreds of players can participate in a single session of FPS and RTS games, as we demonstrate with the game Rokkatan [3].
The worldwide market for computer gaming is already on par with the worldwide market for movie entertainment. The research at the University of Muenster focusses on solutions in the area of scalability and responsiveness suitable for commercial online games like MMORPGs (for example World of Warcraft) or FPS (for example Battlefield 2) and RTS games.

Battlefield 2

World of Warcraft 2. Dynamic Game Resource Providing using the Grid
The results of the research at the University of Muenster in this area demonstrate that Massively Multiplayer Online Gaming for arbitrary game designs require a scalable, multi-server architecture. In order to actually run such game sessions, a large amount of computational resources is needed. There is already an enormous amount of resources set up for online games: The session location service Gamespy (www.gamespy.com) regularly reports over 60.000 running sessions for the ten most popular games, while the number of users actually playing is quite dynamic and ranges from about 50.000 to 250.000 users depending on weekday and daytime. The high-bandwidth, dedicated game servers these sessions run on are statically set up to continuously run the same game session, regardless of how many users actually play.
The group at the University of Muenster currently works on a novel service architecture which will provide game services in a dynamic and on-demand manner. Analogously to a computational Grid, this architecture provides a transparent access to computing resources available to run sessions of various games. Users are able to search, start and book game sessions in advance at different service providers for the time they actually want to play. An overview of the architecture is shown in the following figure.
System Architecture
Using this architecture, the overall efficiency of game server machines is drastically improved, because hosts which are not scheduled to run a game session remain available for other tasks. This opens the possibility to combine entertainment and scientific Grid-computing running on the same resources: Hosts without a game session running are available to run scientific applications and vice versa, leading to a general and efficient usage of high-performance hosts.
Contacts:
Jens Müller,jmueller@math.uni-muenster.de
Sergei Gorlatch,gorlatch@math.uni-muenster.de
[1] J. Müller, S. Fischer, S. Gorlatch, M. Mauve: A Proxy Server-Network for Real-time Computer Games, Euro-Par 2004 Parallel Processing, LNCS, 606-613, 2004.
[2] J. Müller, S. Gorlatch: GSM: A Game Scalability Model for Multiplayer Real-time Games, IEEE Infocom 2005, 2005.
[3] J. Müller, J. H. Metzen, A. Ploss, M. Schellmann, S. Gorlatch: Rokkatan: Scaling an RTS Game Design to the Massively Multiplayer Realm, to appear in ACM SIGCHI International Conference on Advances in Computer Entertainment Technology (ACE 2005), 2005