Client Behavior and Feed Characteristics of RSS, a Publish-Subscribe System for Web Micronews

While publish-subscribe systems have attracted much research interest since the last decade, few established benchmarks have emerged, and there has been little characterization of how publish-subscribe systems are used in practice. This paper examines RSS, a newly emerging, widely used publish-subscribe system for Web micronews. Based on a trace study spanning 45 days at a medium-size academic department and periodic polling of approximately 100,000 RSS feeds, we extract characteristics of RSS content and usage. We find that RSS workload resembles the Web in content size and popularity; feeds are typically small (less than 10KB), albeit with a heavy tail, and feed popularity follows a power law distribution. The update rate of RSS feeds is widely distributed; 55% of RSS feeds are updated hourly, while 25% show no updates for several days. And, only small portions of RSS content typically change during an update; 64% of updates involve less than three lines of the RSS content. Overall, this paper presents an analysis of RSS, the first widely deployed publish-subscribe system, and provides insights for the design of next generation publish-subscribe systems.