Metalevel database programming and visualization with POETView

Abstract

The separation of data model and presentation has been shown to be highly useful for the visualization of data. The Model-View-Controller (MVC) paradigm used by Smalltalk has been accepted as the de facto standard in this area. Over the past two years, a new software architecture has been developed based on the MVC approach. This architecture takes into account the special requirements of the C++ language, object databases (such as POET) and C++ class libraries for GUI development. It is used in commercial products, however it is not available in itself as a separate product. POETView is intended for use in internal tool production and in external project development.

The development of POETView was motivated by the need for reusable user interface and data model components. As significantly more effort is generally required to develop the graphical interface of an application than the algorithms used in the model, we have tried to allow the reuse of existing components whenever possible in different contexts. However, components are not found only at the user interface level. The data model also contains reusable components. We consider reusability to be most effective when the components can be reused in binary form. These objects must therefore be able to communicate with each other at run-time which data are to be displayed. This protocol is at the heart of the POETView architecture. It allows a presentation component to obtain data from the associated data model components and to display them as desired. The protocol also manages any necessary meta-data. In this way, components can be combined at run-time, since the static or compile-time definition of possible aggregations is not necessary.