Check out DDS (disclosure: my company sells an implementation). It's a pub-sub based middleware, slanted toward a data-centric approach, as contrasted with dis

Check out DDS (disclosure: my company sells an implementation). It's a pub-sub based middleware, slanted toward a data-centric approach, as contrasted with distributed objects or message-passing. As far as agree-upon messages... there are plenty of standards to choose from. :) The keys are to be internally consistent and to have an interoperability plan.