A Declarative Approach for Designing and Developing Adaptive Components

An adaptive component is a component that is able to adapt its behavior to di erent execution contexts Building an adaptive application is di cult because of component de pendencies and the lack of language support As a result code that implements adaptation is often tangled hindering maintenance and evolution To overcome this problem we propose a declarative approach to program adaptation This approach makes the speci c issues of adaptation explicit The programmer can focus on the basic features of the application and separately provide clear and concise adaptation information Concretely we propose adaptation classes which enrich Java classes with adap tive behaviors A dedicated compiler automatically generates Java code that implements the adaptive features Moreover these adaptation declarations can be checked for consistency to provide additional safety guarantees As a working example throughout this paper we use an adaptive sound encoder in an audio conferencing application We show the problems associated with a traditional imple mentation using design patterns and how these problems are elegantly solved using adaptation classes