In a model based software system, a set of business rules is scanned, and patterns are identified. The patterns are then compared, and similarities identified which indicate that software can be reused in the system. In one embodiment, identifiers of the rules are scanned. In another embodiment, usage patterns are used for designing a middle layer and generating code. In another embodiment of the invention, a data model is generated by capturing data from a user interface for a business document.