1. A system comprising: a plurality of computers; an overlay network linking the plurality of computers, the plurality of computers including a plurality of publishers, a plurality of subscribers, and a plurality of brokers, the overlay network including a first computer network having a first network protocol, the first computer network carried by a second computer network having a second network protocol; an agent carried by each of the publishers, the subscribers, and the brokers that adjusts the network's topology based upon collected runtime data of at least one of condition of each link within the network and broker availability to any publisher and subscriber; and an optimizer to automatically select at least one backup bridge and data path of each of the subscribers when a local domain's overlay node fails such that total traffic in the overlay network is minimized and message delay constraints between publisher and subscriber pairs are satisfied.