Sync-MS: Synchronized Messaging Service for Real-Time Multi-Player Distributed Games

by Yow-Jian Lin, Katherine Guo and Sanjoy Paul

• Presented by Greg Kempe
• The paper (PDF)
• Presentation slides (PPT)

Summary

Real-time, online multi-player games are becoming increasingly popular due to advances in game design and the proliferation of broadband Internet access. However, fairness remains a major challenge when players over large geographic areas participate in a client-server based game together. This paper proposes a game-independent, network based service, called Sync-MS, that balances the trade-off between response time and fairness. Sync-MS uses two mechanisms, Sync-out and Sync-in, to address state update fairness and player action fairness, respectively. Two metrics, ahead and behind measured against the fair order, are defined to evaluate Sync-MS’s fairness performance. Simulation results show that Sync-MS dramatically improves player action fairness for all players while slightly increases average response time for players with shorter network delay to the game server

Discussion

Points that were raised during the discussion include:

• Are the assumptions valid? Is 100ms really a good delay time?
• Is "fairness" really fair? Players paying for high-speed connections would like to have high-speed interactive games.
• The technique uses weightings to get better responsiveness while maintaining fairness. How should the weightings be determined?
• Their concept of fair ordering seems intuitive and useful --- could it be used to measure the effectiveness of similar techniques, such as bucket systems?

References

• Katherine Guo's website
• Review on a follow up paper, also presented in the course.