As part of the analytical process, we must discern the types of objects or components that will be used in the application. There are a number of common object types that have been identified based on their usage, and as it happens, these object types relate directly to J2EE components. These object types are as follows.
Not all object definitions will fit clearly into one of these categories. In fact, it makes very good sense to create helper objects or convenience objects to facilitate development. But the top-level domain objects, which we referred to earlier, should each fall into one of these categories. The following sections explain these object types in more detail.
An entity ...