A Formal Approach to Component Adaptation and Composition

Component based software engineering (CBSE), can in principle lead to savings in the time and cost of software development, by encouraging software reuse. However the reality is that CBSE has not been widely adopted. From a technical perspective, the reason is largely due to the difficulty of locating suitable components in the library and adapting these components to meet the specific needs of the user. Formal approaches to retrieval – using formal notations for interface specification, and semantic based matching techniques – have been proposed as a solution to the retrieval problem. These approaches are aimed at overcoming the lack of precision and ambiguity associated with text-based component interfaces, requirements and retrieval techniques. However these approaches fail to adequately address the problem of component adaptation and composition. In this paper we describe how component adaptation and composition strategies can be defined using parameterised library templates. We define a variety of templates, including wrapper templates that adapt a single program component, and architecture templates that combine program components. We include definitions for sequential architectures, independent architectures and alternative architectures. These library templates are formally specified, so we are able to employ existing formal-based retrieval strategies to match problem specifications against library templates. We discuss how adaptation and composition can be semi-automated by the library templates defined in this paper in combination with existing re-