Mesh-Based Content Routing using XML

Alex C. Snoeren, Kenneth Conley, and David K. Gifford.
Proc. of the 18th ACM Symposium on Operating Systems Principles, October 2001.

We have developed a new approach for reliably multicasting time-critical data to heterogeneous clients over mesh-based overlay networks. To facilitate intelligent content pruning, data streams are comprised of a sequence of XML packets and forwarded by application-level XML routers. XML routers perform content-based routing of individual XML packets to other routers or clients based upon queries that describe the information needs of down-stream nodes. Our PC-based XML router prototype can route an 18 Mbit per second XML stream.

Our routers use a novel Diversity Control Protocol (DCP) for router-to-router and router-to-client communication. DCP reassembles a received stream of packets from one or more senders using the first copy of a packet to arrive from any sender. When each node is connected to n parents, the resulting network is resilient to (n-1) router or independent link failures without repair. Associated mesh algorithms permit the system to recover to (n-1) resilience after node and/or link failure. We have deployed a distributed network of XML routers that streams real-time air traffic control data. Experimental results show multiple senders improve reliability and latency when compared to tree-based networks.

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