1. IVR Presentation Topic:A peer-to-peer message exchange scheme for large scale networked virtual environment. (N19) Presented by Feng SHEN, u3390679

2. Content table Some keywords Background of this paper Peer-to-peer message exchange scheme Simulation Questions

3. Keyworkds Net-VE: Networked Virtual Environment P2P: Peer-to-peer S/C: Server/Client architecture AOIM: Area of Interest Management

4. Background 2002, multi-user based game & application become a big business Increase of user number Require high performance hardware & complex software systems

5. MMORPG in 2002 EverQuest holds 400,000 registered users Interact in one consistent VE in real-time Big challenge for system scalability Dominant factor affects scalability -- the way to exchange updated message

6. Solution in 2002 To solve the problem, many communication architectures are proposed Peer-to-peer Server/client architecture

7. P2P architecture Unicast – O(N 2 ) for N entities – bad performance for large N Multicast combined with area partioning scheme – works well, but multicast not widely avaliable on the Internet

8. Server/Client Entity  Server  entities Server – bottleneck Failure of server = failure of whole system Multi-server/client * Over-provision * Estimate no of entities * Too costly for large-scale applications

9. Proposal of this paper Scalable p2p message exchange scheme Peer-to-peer architecture No multicast infastructure No centralized mechanism

10. Details of scheme A. Bootstrap method B. Creating overlay network – Each entity connects neighbouring entities – Scheme keeps latency smaller than S/C architecture – Network deployed without multicast infastructure

11. A. Bootstrap method Procedure for an entity enters VE for the first time This entity acquire information of other entities already in VE

12. B. Creating overlay network Entity acquire surrounding entities Classify into two groups AE & LE – AE: Active entities, direct interacation, detail information – LE: Latent entities, potiential interaction, rough information Take the nearest N entities as AE Unicast connects AE

14. Exchange message Information of AE exchanged through unicast connection Information of LE – Each entity compress its AEs’ rough information into list – Exchange this list with its AEs’ lists – Knows LE’s location They should recognize each other, establish direct connection, set AE

15. Simmulation Key issue of creating Neted VE – to keep optimal adjacency relationship of entities in VE Compare result with that from S/C scheme Show scalability & performance

16. S/C entity processor 1. Calculates the entities location at time T 2. Calculates the distance among all the entities to generate a distance table 3. According to the table, inform the nearest N entities of each entity as Active Entity

17. P2P entity processor 1.Updates the location of entity “I” (Entity(I)) at time T 2.Inquire its neighboring entities (Entity(I).AE(J)) about their current locations 3.Then inquire the neighboring entities about the information of their neighboring entities (Entity(Entity(I).AE(J).ID).AE(K))) 4.Calculates the distance among the entities based on the information acquired in the previous step and sort them in order of the distance 5.Set the nearest N enteritis as new Active Entities

20. Qualitative analysis Two models resemble each other To evaluate quantitatively, define N: the no of entities in VE P(I): the no of AEs for entity I in P2P mode Q(I): the no of AEs for entity I in S/C mode

22. Consistency The P2P based message exchange scheme makes it possible for entities to establish almost consistent relationship (>0.9) compared to S/C scheme, independently of the number of the participants in the virtual environment. This scheme scales well.

23. Conclusion The proposed P2P message exchange scheme can build consistent virtual environment in a scalable manner.

24. Questions?