With the advent of large-scale, wide-area networking testbeds, researchers can deploy long-running distributed services that interact with other resources on the Web. The CoDeeN Content Distribution Network, deployed on PlanetLab, uses a network of caching Web proxy servers to intelligently distribute and cache requests from a potentially large client population. We have been running this system nearly continuously since June 2003, allowing open access from any client in the world. In that time, it has become the most heavily-used long-running service on PlanetLab, handling over four million accesses per day. In this paper, we discuss the design of our system, focusing on the reliability and security mechanisms that have kept the service in operation. Our reliability mechanisms assess node health, preventing failing nodes from disrupting the operation of the overall system. Our security mechanisms protect nodes from being exploited and from being implicated in malicious activities, pr...
Limin Wang, KyoungSoo Park, Ruoming Pang, Vivek S.