Control Encapsulation: A Calculus for Exogenous Composition of Software Components

Kung-Kiu Lau 
School of Computer Science, the University of Manchester
Manchester M13 9PL, United Kingdom
kung-kiu@cs.man.ac.uk

Mario Ornaghi
Dipartimento di Scienze dell'Informazione,
Universita' degli studi di Milano
Via Comelico 39/41, 20135 Milano, Italy
ornaghi@dsi.unimi.it

Abstract: 

In current software components models, components do not encapsulate
control, and are composed by connection mechanisms which pass control
from component to component. Connection mechanisms are not hierarchical
in general, and therefore current component models do not 
support hierarchical system construction. In this paper we argue that
control encapsulation by components, together with suitable
composition mechanisms, can lead to a component model that 
supports hierarchical system construction. We show an  
example of such a model and present a calculus for its 
hierarchical composition mechanisms.