Phoenix: A Protocol for Seamless Client Mobility in Publish/Subscribe

This paper presents Phoenix, a routing protocol for content-based publish/subscribe systems that supports seamless client mobility. Our protocol is based on the Simple Routing approach and requires brokers to maintain a global vision of the system with regards to its subscribers. As a consequence, Phoenix provides optimal event routing in both static and mobile client scenarios, and avoids mobility-related flooding of messages. Although the choice of Simple Routing sacrifices maximum scalability due to global propagation of subscriber interest, we show that several optimizations significantly minimize the loss of performance. In fact, when optimized, the performance of the Phoenix routing algorithm is suitable for the scenarios we envision: hybrid wireless networks for sensor/actuator deployments. Additionally, we note that our protocol can be extended to provide brokers with the ability to enforce client migrations for load-balancing purposes.