1. An end-to-end publish/subscription messaging system with a middleware architecture, comprising: one or more messaging appliances configured to receive and route messages; an interconnect utilizing channel-based messaging that routes messages over a first messaging layer based on one or more channels mapped to subscription topics, each of the one or more channels assigned to a communication pathway of a second messaging layer; and a provisioning and management system linked via the interconnect to the one or more messaging appliances and configured to exchange administrative messages with each of the one or more messaging appliances, wherein each of the one or more messaging appliances is further configured to execute the routing of messages by dynamically selecting, in real time, a message transmission protocol and a message routing path.