This paper focuses on design and implementation of a synchronous P2P (Peer-to-Peer) collaboration platform called TOMSCOP (Technology Of Multi-user Synchronous COllaboration Platform). Based on the elementary peer group services offered by the JXTA general framework, TOMSCOP provides the extra four types of services: synchronous message transportation, peer room administration, peer communication support and application space management. By using the four services, different kinds of shared applications for various specific purposes can be relatively easily developed and associated collaborative cyber spaces or communities can be quickly built across the JXTA virtual network overlaid on top of the existing physical networks.