Feed Ex: Collaborative Exchange of News Feeds

摘要

As most blogs and traditional media support RSS or Atom feeds, the news feed technology becomes increasingly prevalent. Taking advantage of ubiquitous news feeds, we design FeedEx, a news feed exchange system. Forming a distribution overlay network, nodes in FeedEx not only fetch feed documents from the servers but also exchange them with neighbors. Among many benefits of collaborative feed exchange, we focus on the low-overhead, scalable delivery mechanism that increases the availability of news feeds. Our design of FeedEx is incentive-compatible so that nodes are encouraged into cooperating rather than free riding. In addition, for a better design of FeedEx, we analyze the data collected from 245 feeds for 10 days and present relevant statistics about news feed publishing, including the distributions of feed size, entry lifetime, and publishing rate. Our experimental evaluation using 189 PlanetLab machines, which fetch from real-world feed servers, shows that FeedEx is an efficient system in many respects. Even when a node fetches feed documents as infrequently as every 16 hours, it captures more than 90% of the total entries published, and those captured entries are available within 22 minutes on average after published at the servers. By contrast, stand-alone applications in the same condition show 36% of entry coverage and 5.7 hours of time lag. The efficient delivery of FeedEx is achieved with low communication overhead as each node receives only 0.9 document exchange calls and 6.3 document checking calls per minute on average.