Building Business Objects

Abstract

While building business applications and overseeing the development of them, I have seen many applications go awry because of the poor construction of the business objects. The rules that the business objects are supposed to implement are not implemented correctly, the rules are implemented in the user interface, or the rules are implemented solely in the database. Each of these three issues has brought more than one system to its knees. I have seen application development cancelled during construction, and I have seen applications scrapped after the construction was complete because of a failure of the business objects. When most of us think of an application, we think about the data the application accesses and the user interface through which the user enters and views information. The truth of the matter is this: These are not the application. The database is a repository for information; it does not do a lot of processing (in some cases, none at all, which is not necessarily right either). The user interface is a window to the data. In a perfect world, the user interface does not do any processing except display the information. The business logic, which is the application, should perform the bulk of the processing of information.