Component Coordination in GLoo

Incorporating components from a number of different sources into a given application is generally considered to be a non-trivial activity. Over the years, various coordination mechanisms have been proposed to tackle this problem. However, even today, the question remains how to best link these coordination mechanisms with an underlying programming paradigm without loosing flexibility. A suitable technique to address this issue is language composition, enabling us to "fine-tune" a programming language on demand. In this compositional approach, we can add new features to the language as we go, within user-defined regions, and without polluting the underlying paradigm as a whole. To test the effectiveness of this technique, we explore a small stream processing framework and its corresponding coordination abstractions in this paper. More precisely, we report on our insights into using GLoo, a functional composition language, for the definition of extensible coordination abstractions that, through the composition of the concepts proxy, method pointer, and Pernici\´s "objects with roles" constitute, collectively, an attractive means to capture and denote inter-component interactions in a user-centric and domain-specific way.