A New Approach to a Self-Organizing Federation of MQTT Brokers

In the Publish/Subscribe (PS) communication paradigm clients producing content (i.e., publishers) send it to a broker, which relays the content to consumers (i.e., subscribers). Communication can happen asynchronously, leaving all the hurdles to the server/broker. MQ Telemetry Transport (MQTT) is the most used P/S protocol in designing IoT applications. The usual MQTT scenario comprises a single broker, making it a potential bottleneck and a single point of failure. Clustering of brokers is the typical approach for scaling MQTT, usually restricting deployment to a single administrative domain. The federation of autonomous brokers is a more flexible approach for scaling the MQTT protocol, with just one representative self-organizing protocol at the moment. We present a new variant for such protocol, providing a well-structured mechanism for building and orchestrating the federation of brokers. The main contribution of this study is to offer a feasible solution for deploying the MQTT federation without requiring critical changes to regular clients. By following the topic naming conventions, clients are unaware they rely on a federation of brokers. To provide a glimpse of our solution in action, a case study demonstrates that the protocol can easily provide flexible reliability with low complexity.