Layered development is best practiced in TIBCO recommends for data virtualization projects.
Data virtualization allows the many different data consumers in an enterprise to connect to virtual data bases and web services that present data in an easy to consume format, while hiding the underlying complexity of the many disparate physical data sources in the enterprise.
It is certainly possible for data developers to build these virtual resources in a single monolithic step. However, a number of benefits may be realized when developers build out their projects using a layered approach TDV enables developers to use as many or as few layers as they want.