A Hot-topic based Distribution and Notification of Events in Pub/Sub Mobile Brokers

Publish/Subscribe-based networks have emerged as suitable candidates for supporting new sort of devices in the Internet of Things. Despite this, there are few mobile broker models that integrate existing subscription and notification models while meet the requirements of these devices. The challenge of creating an uniform and loosely coupled content dissemination network of fixed and mobile devices is gaining importance; so, mobile brokers have to provide not only protocol compatibility but also event coordination and popularity. In this paper, we introduce mechanisms that allow mobile brokers to distribute their subscribers and coordinate the notification of events between fixed and mobile brokers. We propose a hot-topic algorithm that marks the event popularity and depending on this, delegates or recovers subscriptions. Furthermore, we also propose extensions for the MQTT protocol, in order to support our mechanisms. Finally, we show the results of our simulations and confirm that our mechanisms offer advantages for our considered IoT scenario.