PUBLISH & SUBSCRIBE DATA PROCESSING APPARATUS, METHOD AND COMPUTER PROGRAM PRODUCT WITH DECLARATION OF A UNIQUE PUBLISHER BROKER

In a publish/subscribe data processing broker network having a plurality of broker data processing apparatuses each of which has an input for receiving published messages directly from a publisher application and/or receiving subscription data from a subscriber application, a first broker data processing apparatus has: a unit for receiving a data message published on a first topic by a first publisher application; and a unit for forwarding the received published data message to a subscriber application which has requested, by entering subscription data, to receive a message on the first topic; wherein the first broker data processing apparatus sends a declaration to at least one other broker data processing apparatus of said plurality of broker data processing apparatuses declaring that the first broker data processing apparatus is the only broker data processing apparatus that is directly communicating with a publisher application that is publishing on the first topic.