A Component Model for Separation of Control Flow from Computation in Component-Based Systems

Today's component models as well as architectural description languages (ADLs) compose components either using direct or indirect method calls. When using direct method calls, components carry out computation, originate control to and perform communication between each other. When using indirect message calls, components are connected using connectors encapsulating communication between them. The components in these (ADL) systems are supposed to do computation only. However, in this paper we show that components in ADLs not only perform communication as intended but also originate control towards connectors resulting again in a mixture of control and computation inside components. To separate control from computation in component-based systems we have been developing a new component model aimed at separation of control from computation [K.-K. Lau, P. Velasco Elizondo, and Z. Wang. Exogenous connectors for software components. In Proc. 8th Int. SIGSOFT Symp. on Component-based Software Engineering, LNCS 3489, pages 90–106, 2005]. In this paper we show how it can be used to build modular and maintainable systems and argue that our component model has its place in Model-driven architecture.