A method is provided for executing a business date driven application, such as a financial system or a banking application, in an open computing system environment. The method may include accessing a calendar control module to determine an operational mode of the application. The calendar control module is based at least in part on a Julian calendar and may include a Julian calendar day of year field, an application start command field, an application restart command field, and/or a business date indicator field. The method includes executing the business date driven application in accordance with the determined operational mode.