A plurality of protocol stacks are deployed. Each of the protocol stacks includes a plurality of composable protocol modules, and each of the composable protocol modules implements common interfaces. It is detected that a first given one of a plurality of clients wishes to connect to a publication-subscription engine and it is determined whether the first given one of the plurality of clients is to be connected in a secure manner. Responsive to determining that the first given one of the plurality of clients is to be connected in the secure manner, an encrypted instance of a first appropriate one of the plurality of protocol stacks is instantiated to effectuate the secure connection. The first given one of the plurality of clients is authenticated and authorized.