1. A system for generating a service interface definition for a data source from an application definition, the application definition including a screen component having screen definitions expressed in a first structured definition language for defining the visualization of a data structure when displayed on a graphical user interface of a device when in communication with the data source over a network, the visualized data structure related to data content associated with the messages communicated over the network between the device and the data source via the service interface, the system comprising: a service interface generation engine configured for coordinating the processing of screen control mappings identified from the screen component in generation of the service interface, the screen control mappings for defining a work flow of the screen described by the screen component in the context of the application; a message definition module of the engine for generating a message definition set related to the identified control mappings, the message definition set for describing the data structure communicated between the device and the data source, the message definition set expressed in a second structured definition language; and an operation definition module of the engine for generating an operation definition describing an action supported by the data source, the operation definition expressed in the second structured definition language; wherein the message definition set is assignable to the operation definition during generation of the service interface.