On the cost and safety of handoffs in content-based routing systems

Content-based routing of information and publish/subscribe have been proposed as a communication paradigm for advanced and mobile applications. In content-based routing, messages are forwarded based on queries on their content that clients and routers establish beforehand. In this paper, we examine the cost and safety of handoff protocols for subscribers and publishers in content-based routing networks. We examine two useful properties for mobility-aware content-based routing systems, namely completeness and mobility-safety. Then we determine the upper and lower bound handoff costs for three interesting topologies, a number of optimizations, and show that if completeness cannot be assumed the signalling cost is considerably higher and flooding needs to be used. We present simulation results for subscriber mobility and mobility-safety proofs for the investigated protocols. Both theoretical and experimental results show that rendezvous points may be used to significantly reduce the signalling cost of handoffs.