Corona: A High Performance Publish-Subscribe System for the World Wide Web

Despite the abundance of frequently changing information, the Web lacks a publish-subscribe interface for delivering updates to clients. The use of naı̈ve polling for detecting updates leads to poor performance and limited scalability as clients do not detect updates quickly and servers face high loads imposed by active polling. This paper describes a novel publish-subscribe system for the Web called Corona, which provides high performance and scalability through optimal resource allocation. Users register interest in Web pages through existing instant messaging services. Corona monitors the subscribed Web pages, detects updates efficiently by allocating polling load among cooperating peers, and disseminates updates quickly to users. Allocation of resources for polling is driven by a distributed optimization engine that achieves the best update performance without exceeding load limits on content servers. Large-scale simulations and measurements from PlanetLab deployment demonstrate that Corona achieves orders of magnitude improvement in update performance at a modest cost.