1. 1 Peer-to-Peer Networked Virtual Environments Shun-Yun Hu ( 胡舜元 ) (syhu@yahoo.com) CSIE, National Central University, Taiwan 2007/10/18

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5. 5 NVE: A Shared Space

6. 6 Engineering Everquest

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8. Massively Multiplayer Online Games MMOGs are growing quickly 9 million registered users for World of Warcraft Over 500,000 concurrent players But… 3,000 max. per world Can we have millions in the same world?

9. 9 A model for NVE Many nodes on a 2D plane Message exchange with those within Area of Interest (AOI) How does each node receive the relevant messages? Area of Interest

10. 10 A simple solution (point-to-point) But…too many irrelevant messages N * (N-1) connections ≈ O(N 2 )  Not scalable! Source: [Funkhouser95]

11. 11 A better solution (client-server) Message filtering at server to reduce traffic N connections = O(N)  server is bottleneck Source: [Funkhouser95]

12. 12 Current solution (server-cluster) Still limited by servers. Expensive to deploy & maintain. Source: [Funkhouser95]

13. The Problem Client-server: has inherent resource limit Resource limit [Funkhouser95]

14. The Solution Peer-to-Peer: Use the clients’ resources Resource limit [Keller & Simon 2003]

15. Voronoi-based Overlay Network (VON)

16. 16 If you can connect only with your AOI Neighbors…

17. 17 Voronoi Diagram 2D Plane partitioned into regions by sites, each region contains all the points closest to its site Can be used to find k-nearest neighbor easily Neighbors Site Region

18. 18 Design Concepts Identify enclosing and boundary neighbors Each node constructs a Voronoi of its neighbors Enclosing neighbors are minimally maintained Mutual collaboration in neighbor discovery CircleArea of Interest (AOI) Whiteself Yellowenclosing neighbor (E.N.) L. Blueboundary neighbor (B.N.) PinkE.N. & B.N. Greennormal AOI neighbor L. Greenunknown neighbor Use Voronoi to solve the neighbor discovery problem

19. 19 Demonstration Simulation demo Random movements (100 nodes, 1200x700 world) Local vs. global view Dynamic AOI adjustment

20. P2P 3D Streaming

21. 21 P2P 3D Streaming MMOGs today need CD installation (too slow!) Progressive 3D data transfer allows on- demand download But 3D data is huge

22. 22 overlapped visibility = shared contents

23. 23 Get data from your neighbors! ★ : Self ▲: Neighbors

24. 24 Our P2P 3D streaming prototype (with NTU CMLab)

25. P2P Voice for MMOG

26. 26 P2P Voice for MMOG People communicate mainly by typing. But, talking is more natural (Skype, Teamspeak, etc.) However, server bandwidth is limited for voice

27. 27 A basic P2P voice model 5 audio streams 12 audio streams

28. 28 An improved model 4 audio streams

29. So if P2P NVE can be made… No server as bottleneck  scalable Commodity hardware  affordable 2D web  3D web Earth-scale virtual environments (millions of people)

30. 30 A Last Note… “Your time is limited, so don't waste it living someone else's life. Don't be trapped by dogma — which is living with the results of other people's thinking. Don't let the noise of others' opinions drown out your own inner voice. And most important, have the courage to follow your heart and intuition. They somehow already know what you truly want to become. Everything else is secondary. “ – Steve Jobs (commencement address to Stanford graduates, 2005)

31. 31 Q&A VON: A Scalable Peer-to-Peer Network for Virtual Environments IEEE Network, vol. 20, no. 4, Jul./Aug. 2006 Thank you! syhu@yahoo.com http://vast.sourceforget.net (http://vast.sf.net)