A functional software architecture (FSA) is an architectural model that identifies enterprise functions, interactions and corresponding IT needs. These functions can be used as reference by different domain experts to develop IT-systems as part of a co-operative information-driven enterprise. In this way both software engineers and enterprise architects are able to create an information-driven, integrated organizational environment. A functional software architecture (FSA) is an architectural model that identifies enterprise functions, interactions and corresponding IT needs. These functions can be used as reference by different domain experts to develop IT-systems as part of a co-operative information-driven enterprise. In this way both software engineers and enterprise architects are able to create an information-driven, integrated organizational environment.