Optimal on-line algorithms for an electronic commerce money distribution system

We consider the money distribution problem
for a micro-payment scheme using a distributed server system;
in particular, for an automatic charging scheme named PayPerClick that allows Internet users to
view Web pages for which access charges are levied without tedious payment procedures.
A major bottleneck in the scheme is the network traffic caused by the distribution
of electronic money to many different servers.
We propose a simple on-line algorithm for distributing electronic money to servers so that the network traffic is minimized.
The algorithm achieves the optimal online competitive ratio.
We also consider a {\em weighted} version, for which we give an asymptotically optimal online algorithm within a constant factor.