Vector-field consistency

Vector-Field Consistency^{[nb 1]} is a consistency model for replicated data (for example, objects), initially described in a paper^[1] which was awarded the best-paper prize in the ACM/IFIP/Usenix Middleware Conference 2007. It has since been enhanced for increased scalability and fault-tolerance in a recent paper.^[2]

Description

This consistency model was initially designed for replicated data management in adhoc gaming in order to minimize bandwidth usage without sacrificing playability. Intuitively, it captures the notion that although players require, wish, and take advantage of information regarding the whole of the game world (as opposed to a restricted view to rooms, arenas, etc. of limited size employed in many multiplayer games), they need to know information with greater freshness, frequency, and accuracy as other game entities are located closer and closer to the player's position.

It prescribes a multidimensional divergence bounding scheme, based on a vector field that employs consistency vectors k=(θ,σ,ν), standing for maximum allowed time - or replica staleness, sequence - or missing updates, and value^{[nb 2]} - or user-defined measured replica divergence, applied to all space coordinates in game scenario or world.

The consistency vector-fields emanate from field-generators designated as pivots (for example, players) and field intensity attenuates as distance grows from these pivots in concentric or square-like regions. This consistency model unifies locality-awareness techniques employed in message routing and consistency enforcement for multiplayer games, with divergence bounding techniques traditionally employed in replicated database and web scenarios.

Notes

1. _{Designation coined by L. Veiga.}
2. _{Since in the Greek alphabet there was no letter for the vee sound, the nu letter was preferred for its resemblance with the roman V, for value, instead of β (beta) for the vee sound in contemporary Greek speaking.}

References

1. Nuno Santos, Luís Veiga, Paulo Ferreira (2007). "Vector-Field Consistency for Adhoc Gaming" (PDF). ACM/IFIP/Usenix Middleware Conference 2007.
2. Luís Veiga, André Negrão, Nuno Santos, Paulo Ferreira (2010). "Unifying Divergence Bounding and Locality Awareness in Replicated Systems with Vector-Field Consistency" (PDF). JISA, Journal of Internet Services and Applications, Volume 1, Number 2, 95-115, Springer, 2010.