1. A method for controlling interactions between a publication-subscription engine and a plurality of clients, said method comprising the steps of: deploying a plurality of protocol stacks, each of said protocol stacks comprising a plurality of composable protocol modules, each of said composable protocol modules implementing common interfaces; detecting that a first given one of said plurality of clients wishes to connect to said publication-subscription engine; determining whether said first given one of said plurality of clients is to be connected in a secure manner; responsive to determining that said first given one of said plurality of clients is to be connected in said secure manner, instantiating an encrypted instance of a first appropriate one of said plurality of protocol stacks to effectuate said secure connection; authenticating said first given one of said plurality of clients; and authorizing said first given one of said plurality of clients.