A method and associated system for interfacing between a caller application and a service module. A service module builds a service module data structure pursuant to a previously received request. The request includes at least one caller application attribute describing the request. The service module data structure includes a generic service document and at least one service module attribute. Each service module attribute is stored in a relational table of the service module data structure. The requests serviced within the service module data structure, resulting in instantiating the generic service document. The generic service document is returned to the caller application. Building each service module attribute includes: constructing the generic service document and creating at least one container in the generic service document. Each container is respectively associated with each service module attribute in each mapping of at least one mapping.