Towards Context Independent Extra-functional Properties Descriptor for Components

Architectures based on composing target application functionality from pre-existing components have been successfully used in many projects, yet there are several aspects in which they fail to reach the desirable level of maturity. Since different vendors may provide components with the same functionality, extra-functional properties must be taken into account to help the developer to select the component which suits the final system. In addition, a selected component must conform to the target deployment environment. This paper addresses the problem of inadequate means to define extra-functional properties on components in a way that allows to express component's properties with respect to different computational environments. We provide a representative survey of the current state of the art for extra-functional properties and propose a formalism based on existing approaches which addresses this inadequacy. Our formalism further allows us to use the extra-functional properties for describing the dependency between a component and a deployment environment referred to as deployment contracts. Our approach uses a system of registries that has the advantage of a consistent interpretation of the extra-functional properties found on any given component regardless of its usage context and that separates the semantics and the syntax of each property.