Object-oriented architecture is revolutionizing the software scene: application objects are replacing application packages. Instead of complete application packages, such as a desktop publishing system, application developers—and in the future also users—buy application objects that implement smaller, self-contained functional units, such as a spell checker. These application objects, available on the market as well as individually developed ones, are integrated into individual application environments tailored to the user. This allows for the integration of freely available application objects with individually developed ones to form a customized application environment. This radical change in the software scene exceeds the introduction of graphical user interfaces in its importance and effects. OLE2 is currently the most important basis for this.