1. A method for handling messages on a message transmission backbone within a data processing system, said method comprising: generating an allowable message types data structure, wherein each entry of said allowable message types data structure includes information for identifying an allowable message type; repetitively detecting a change in a status of a module within a group of loaded programs, wherein said group of loaded programs includes multiple data processing software modules; in response to detecting the change in the status of the module within the group of loaded programs, modifying a corresponding entry within said allowable message types data structure; and selectively communicating a message to said group of loaded programs based on whether an item of identifying information within said message meets a criterion of said entries within said allowable message types data structure.