A basis for composition language CL

CL is a composition language for predictable assembly from certifiable components. An application assembly process is predictable if the runtime behavior of an assembly of components can be predicted from known properties of components and their patterns of interaction. CL is similar to other composition languages that combine a component and connector style of description with a core compositional semantics specified in a process algebra. CL differs from these in its explicit treatment of details that are usually abstracted or ignored. For example, CL makes explicit the allocation of execution threads to component behavior:, this distinguishes concurrent from sequential behavior, and leads to potentially smaller state spaces as well as more accurate behavioral descriptions. This report describes the main concepts of CL and its rudimentary graphical syntax. This report also defines and illustrates the compositional semantics for CL using Hoare's CSP. The twin objectives of this report are to consolidate our current thinking about an ideal CL and to provide a starting point for the design of a practical and implementable CL. This report closes with a discussion of several open issues that must be resolved before this second objective can be satisfied.