Rewriting a Pattern Language to Make it More Expressive

Representing and selecting patterns remains largely an empirical task. It is difficult to recognize when to apply a given pattern, as well as the consequences its application could generate. This creates the need for extensions to the existing pattern representation. Elsewhere, we have proposed an explicit representation of the forces involved in a pattern and their interrelationships. It interprets forces as non-functional requirements, and uses the non-functional requirements framework developed in requirements engineering to analyze the context of applicability of a pattern, and its consequences. In this paper we describe a case study in which we apply our new pattern representation to an existing pattern language. We illustrate how the extended pattern representation enables us to discover contributions made by the patterns to overall system concerns that were implicit in the textual description of the pattern.