Scalable Distribution of XML Content with XNet

The XNET XML content network was designed to implement efficient and reliable distribution of structured XML content to very large populations of consumers. For that purpose, our system integrates several technologies: the routing protocol XROUTE makes extensive use of subscription aggregation to limit the size of routing tables while ensuring perfect routing (that is, an event is forwarded to a link only if it leads to an interested consumer). The filtering engine XTRIE uses a sophisticated algorithm to match incoming XML documents against large populations of tree-structured subscriptions, whereas the XSEARCH subscription management algorithm enables the system to efficiently manage large and highly dynamic consumer populations. Finally, our XNET system integrates reliability mechanisms to guarantee that its state is consistent with the consumer population and implements several approaches to fault tolerance to recover from various types of router and link failures. We have analyzed the efficiency of our techniques with various simulations, and to assess the performance of our system in realistic settings and show that it is perfectly suitable for large-scale distributed environments, we have performed a large-scale experimental deployment on the PlanetLab testbed.