The next diagram shows an extremely cropped version of any database ERD. Basically, it is just to give an idea of a database model to show the various departments that an enterprise may have. Note that each department may have implemented their own applications, or are using some vendor applications or hybrid, and can also have a variety of storage layers in an inconsistent or incompatible manner. Hence the need for a service- based standardized communication model, so as to enable them to talk together in a unified manner, across the organization: