The use of components in development of complex software systems can surely have various benefits. Their testing, however, is still one of the open issues in software engineering. Both the developer of a component and the developer of a system using components often face the problem that information vital for certain development tasks is not available. Such a lack of information has various consequences to both. One of the important consequences is that it might not only obligate the developer of a system to test the components used, it might also complicate these tests. This article gives an overview of component testing approaches that explicitly respect a lack of information in development.

Hypertext-based user interfaces have become attractive for many distributed applications today, but they do not reach the usability level of window-based UIs. Because of insufficient dialog control logic, they cannot manage nested and hierarchical dialog structures that users have come to expect from window-based UIs. We therefore present a framework that implements a dialog control logic capable of handling complex, nested dialog structures, and introduce a notation and an XML-based language for specifying such dialog structures. Key concepts are the encapsulation of multiple dialog steps in context-independent dialog modules that can be nested arbitrarily, and the specification of multiple devicespecific interaction patterns for a single deviceindependent application logic. The framework allows black box reuse, leaving only the implementation of the application logic, the design of the user interface and the specification of the dialog flow to application developers.