Topic-based distributed publish-process-subscribe system with metrics on geographic distance and permissible delay

As IoT devices spread, real-time data analysis and notification are increasingly important. To achieve low latency notifications in edge environments, we have proposed a distributed publish-process-subscribe system that allows multiple edge servers to handle a single topic. In our system, topic allocation to edge servers is formalized as a notification delay optimization problem. In this article, we introduce new metrics that consider the geographic distance of respective pub/sub pairs, or the permissible delay defined by each topic. Using these metrics succeeded in reducing the notification delay to neighboring subscribers and prioritizing topic allocation to meet the delay limit in simulation.