Large softwaresystemsrequiredecompositionalmechanismsinorder tomake themtractable. Traditionally, MILs and IDLs have played this role by providing notations based on definition/use bindings. In this paper we argue that current MIL/IDLs based on definition/use have some serious drawbacks. A significant problem is that they fail to distinguish between "implementation" and "interaction" relationships between modules. We propose an alternative model in which components interact along well-defined lines of communication
Robert J. Allen, David Garlan