A Dynamic Area of Interest Management and Collaboration Model for P2P MMOGs

1. A Dynamic Area of Interest Management and Collaboration Model for P2P MMOGs 張晏誌 行動計算與寬頻網路實驗室 王國禎 教授

2. Introduction • The commercial MMOGs use client-server architecture which is expensive to deploy and maintain. For example, “Second Life” has approximately 5000 servers to support the virtual space.

3. Introduction • When a player performs an action or generates an event affecting the virtual space, the game state of all other players influenced by that action or event must be updated. • The amount of information required to exchange between players roughly depends on the population of in the interested area.

4. Introduction • There are two extremes to model AOI among the users for distributed simulations. • The first one is the static geographical partitioning implemented at the initialization phase of a game or a simulation.

5. Introduction • The second extreme for modeling interest is behavioral. • But the ease with which mapping processing resources or servers can be applied in geographic regionalization, little effort has been invested in mapping the behavioral approach

6. Introduction • Even though behavioral modeling is the ultimate goal for managing the interest of the parties, geographic regionalization is not without its merits and can be coupled with behavior-based communications.

7. AoI Management • The interest management for an MMOG can be abstracted using a publish-subscribe model. • The space-based area of interest management is typically based on proximity, and can be realized in terms of an aura-nimbus information model.

8. Game Space & AoI • Mapping an area of interest into a fixed size zone, i.e. unification of an AOI to a zone, is straightforward. • Due to the nature of a game, most of the times an area of interest overlaps multiple zones and breaks the significance of the zone formation. • It requires regular inter-zone communication for synchronization.

9. Game Space & AoI • Notation • aoi(pi) is the AoI of player i • Gspace = ∪AOIj

10. ZonelessAoI Management • Say, an AOI has k players represented by AOI(i) = {pi1 , pi2 , ..., pik}. We form a convex hull to present such an AOI. • A convex hull can be bound with a time complexity of O(nh), where n is the number of points in the set, and h is the number of points in the hull.

11. ZonelessAoI Management • Considering the nature of the game at hand, we do not redefine the convex hull at that instant as we do not know whether the player is returning back soon. • Two attributes are incorporated to make the decision while really redefining the convex hull for each candidate. • Time-span • Safty-edge

12. ZonelessAoI Management • Safety-edge • Time-span • A temporal reference that used to avoid premature decision.

13. Inter AoI Communication • The simple intersection of two AoIsis good enough to uncover the overlapped members. • From the design it is evident that each member of the overlapped AOIs must stay at a safety-edge in each AOIs and being a member of the respective overlays. • This ensures each player receives all messages from the all AOIs where it belongs and redeems the necessity of explicit inter-AOI communication.

14. Simulation and Analysis • It seems that the performance improves as the size of AOI increases in terms of the players. So for a moderate sized AOI, i.e. the size of AOI is 30, only 34% players are involved for AOI maintenance.

15. Reference • DewanTanvirAhmed, ShervinShirmohammadi, “A Dynamic Area of Interest Management and Collaboration Model for P2P MMOGs”, 12th 2008 IEEE/ACM International Symposium on Distributed Simulation and Real-Time Applications