A simplified control system provides a uniform interface to a Java-based POS application. A new interface defining a method SetEntry for passing an entry point to a database to a device service object is created in the device service object which loads this interface as a rule. This allows greater freedom designing the device service object and makes it possible to write better service objects. Device service objects for other manufacturers and other types of devices can also be loaded by a shared factory class, and a simpler JavaPOS system can be provided at low cost.