According to an embodiment of the present invention, there is provided a method of routing a message to one of a plurality of available processing systems, comprising the steps of detecting the presence of a destination identifier in the message, and where the presence of the destination identifier is detected, forwarding the message to the processing system identified thereby. Where the presence of the destination field is not detected the steps of determining a destination processing system for processing the message, inserting into the message a destination identifier identifying the determined destination processing system, and forwarding the message to the determined processing system may be performed.