1. A network system comprising: a plurality of interconnected nodes defining a communications network, with at least one of the nodes configured to send messages over the communications network and at least one of the nodes configured to receive messages over the communications network; and at least one identifier from a pre-determined group of identifiers is associated with each of the nodes and identifies only those functionalities that are applicable to that node; wherein at least one of the nodes transmits the at least one identifier by a message sent over the communications network for receipt by at least one of the nodes to thereby publish the functionalities over the communications network.