An Open Component Model and Its Support in Java

This paper presents Fractal, a hierarchical and reflective component model with sharing. Components in this model can be endowed with arbitrary reflective capabilities, from black-boxes to components that allow a fine-grained manipulation of their internal structure. The paper describes Julia, a Java implementation of the model, a small but efficient run-time framework, which relies on a combination of interceptors and mixins for the programming of reflective features of components. The paper presents a qualitative and quantitative evaluation of this implementation, showing that component-based programming in Fractal can be made very efficient.