Research and implementation of distributed time service in distributed object environment

Distributed time service is a basic object service in distributed computing environment based on CORBA. We present a clock synchronization method based on clock groups. We divide machines in a system into groups, while nodes in a group are in the same LAN. There is a master clock and several slave clocks in a group, which carry out intra-group synchronization. Master clocks of all groups together accomplish inter-group synchronization. Such a dividing-to-group synchronization method makes the system scalable and flexible. At the same time, it reduces machines spanning LANs to attend synchronization, thus synchronization overhead is reduced. We have implemented clock synchronization based on clock groups in our experimental distributed object environment.