Abstract
Abstract: Trends in component-based software development point to increased use of pre-existing or purchased components. A consequence of this type of development is that systems are being composed of large-grained components over which the developer wields little control. This and other issues related to the use of commercial components has created a new class of design problem that is not addressed by traditional development methods and tools. In this paper we describe this class of design problem, and introduce Ensemble, a conceptual language that supports assembling software systems from commercial components.