1. A method for securely establishing communication in a multicast group of nodes of a network, in which the nodes of the network include publishers and subscribers, the method comprising the computer-implemented steps of: registering a publisher and a subscriber with an event server; wherein the event server is communicatively connected to a directory that stores objects representing event types; in response to registering the publisher, the event server determining whether the publisher is authorized to produce a particular event, which corresponds to a particular event type, by checking in the directory a particular object that represents the particular event type; in response to registering the subscriber, the event server determining whether the subscriber is authorized to receive the particular event by checking in the directory the particular object that represents the particular event type; and storing, within the event server, a group session key for establishing a multicast group, wherein the multicast group includes the publisher and the subscriber, and the group session key is encrypted in a first message that has a prescribed format.