Exposing the skeleton in the coordination closet

Abstract

One of the ways in which we cope with large and complex systems is to abstract away some of the detail, considering them at an architectural level as compositions of interacting components. To this end, the variously termed Coordination, Configuration and Architectural Description Languages (ADL) facilitate description, comprehension and reasoning at that level, providing a clean separation between individual component behaviour and their interaction in a software architecture. However, in the search to provide sufficient detail for reasoning, analysis or construction, many approaches are in danger of obscuring the essential structural aspect of the architecture, thereby losing the benefit of abstraction. In this paper we argue for the use of a concise and simple language explicitly designed for describing architectural structures. This can be used to provide the "skeleton" upon which to add the particular details of concern when necessary. Systems described in this way have an explicit and exposed skeleton which, being shared, helps to maintain consistency between the various elaborated views. To illustrate our approach, we use the Darwin architectural description language and the Tracta approach for compositional reachability analysis.