Supporting architectural concerns in component interoperability standards

There has been considerable work in industry on the development of component-interoperability models, such as COM, CORBA and JavaBeans. These models are intended to reduce the complexity of software development and to facilitate reuse of off-the-shelf components. The focus of these models is syntactic interface specification, component packaging, intercomponent communication, and bindings to a runtime environment. What these models lack is a consideration of architectural concerns—specifying systems of communicating components, explicitly representing loci of component interaction, and exploiting architectural styles that provide well understood global design solutions. The work described involves introducing support for architectural concerns in component models, particularly studying techniques to support notions of architectural style and explicit connectors. The JavaBeans component model has been enhanced to support component composition according to the C2 architectural style. The approach enables the design and development of applications in the C2 style using off-the-shelf Java components or `beans' that are available to the designer. The techniques underlying the approach are described, along with a composition environment called `ARABICA' that embodies these techniques. A number of important issues that must be addressed when extending component standards to support architectural concerns are identified.