a method and associated system for interfacing between a caller application and a service module . upon receiving a request for performing a transaction that includes at least one caller application attribute describing the request , the service module builds a service module data structure pursuant to the received 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 request is 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 .