Abstract: Methods for bridging computers functioning as Publish/Subscribe brokers are provided to build a distributed cluster for scalability by enabling publishers to connect to one broker and subscribers to that publisher to connect to a different broker. In one aspect, a method includes listening to an internal bridge port on one broker for receiving bridge connections from other brokers in the cluster, and in parallel, connecting to the internal bridge ports of each of the other brokers in the cluster, waiting for all such incoming and outgoing bridge connections to be completed, and then opening up the external port for serving actual clients. The method also includes creating separate bridges for each direction of traffic to make the broker code completely symmetric and also supporting the creation of an arbitrary number of bridge connections between each pair of brokers for each direction to reduce latency.

Abstract: Methods for bridging computers functioning as Publish/Subscribe brokers (e.g. MQTT brokers) are provided as a means to build a distributed cluster for scalability by enabling publishers to connect to one broker and subscribers to that publisher to connect to a different broker. In one aspect, a method includes listening to an internal bridge port on one broker for receiving bridge connections from other brokers in the cluster, and in parallel, connecting to the internal bridge ports of each of the other brokers in the cluster, waiting for all such incoming and outgoing bridge connections to be completed, and then opening up the external port for serving actual clients. The method also includes monitoring that the bridge connection is alive and healthy throughout the operation of the broker and upon detection of connection failure, storing the messages in a persistent store and replaying them on the bridge connection once it is restored.