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A Two-tier Overlay Publish/Subscribe System for Sensor Data Stream Using Geographic Based Load Balancing

Publish/Subscribe mechanism is one of key technologies for handling real-time data stream in decentralized environments. While recent studies have showed that publish/subscribe systems should support not only data filtering but also in-network data processing, scalability issue is addressed due to data concentrations on specific nodes. To solve the scalability issue, we propose a Publish/Subscribe system consisting of two-tier overlay network: one overlay network is designed as a geographic overlay network, which is used to maintain fundamental information, on the other hand, data transfer networks are constructed to perform in-network data processing and dynamic load balancing. By using these two networks, we could implement geographic based dynamic subscription reallocation mechanism. This mechanism enables to achieve scalability and avoid data/load concentrations on large-scale Publish/Subscribe systems. We present an evaluation of the our approach through simulation. We compare our approach to another DHT based Publish/Subscribe system, focusing on data transfer during subscription. Our results show that our dynamic subscription reallocation approach avoids data concentration to specific node.