Towards Logical Clocks in P2P-based MMVEs

Abstract

A crucial requirement for peer-to-peer-based Massively Multiuser Virtual
Environments (P2P-based MMVEs) is the accurate and reliable synchronization of
actions among the users (processes). To do so, clock synchronization protocols
can be used. In this paper we first analyze the usage of standard vector clocks for
this purpose and show their deficits (e.g. growing large). Then we present a novel
variation of vector clocks – pruned vector clocks – which overcome the deficits of
standard vector clocks and are therefore suited for their usage in MMVEs. The basic
idea of pruned vector clocks is to prune all entries in a vector clock, which are not
relevant at some point in time. We show, that with this approach vector clocks will
stay constant in size and still provide the necessarily synchronization among the
processes.