The object-oriented programming paradigm has already proven its usefulness in numerous projects, most of them dealing with graphical user interfaces or visualization in general. But this programming paradigm is undoubtedly more than a mere programming technique for user interfaces. Thus we initiated a project with the major aim to examine the impact object-oriented programming can have on the design and implementation of automation software. The basis for our study is the implementation of an application framework for process automation software, which we already used in the implementation of process control software for a ladle furnace (part of a steel plant). The framework was implemented on SUN SPARCstations using ET++ (a user interface application framework) and C++.