1. A method comprising: receiving, by a message broker subsystem, a message intended for delivery to a recipient software application instance; determining, by the message broker subsystem, that the recipient software application instance is included in a plurality of functionally equivalent software application instances that are registered with a global directory service subsystem that is communicatively coupled to the message broker subsystem; automatically selecting, by the message broker subsystem, a software application instance from the plurality of software application instances for receipt of the message in accordance with a load balancing heuristic; and attempting, by the message broker subsystem, to deliver the message to the selected software application instance.