Message handling in a data processing system

An exemplary embodiment of this disclosure is a method for operating a data processing system, where the data processing system includes a service bus connected between a client and a server. The service bus includes one or more applications configured to mediate message flow between the client and the server. The method includes receiving a message from the client at the service bus, and mediating the message at a message-mediating application of the service bus. The mediation includes adding a header to the message, the header defining a source and a predetermined condition under which a target can respond directly to the source. The source is either the client or an application of the service bus, and the target is either an application of the service bus or the server.