A method of publishing a publication message includes receiving, at one of a plurality of first relays, a subscription request from a first client and transmitting the subscription request from the one of the plurality of first relays to only one of a plurality of central relays. The method also includes receiving, at another of the plurality of first relays, a publication request from a second client. The publication request includes the publication message. The method further includes transmitting the publication message from the another of the plurality of first relays to all of the plurality of central relays, transmitting the publication message from at least one of the plurality of central relays to the one of the plurality of first relays, and transmitting the publication message from the one of the plurality of first relays to the first client.