Design pattern-based model transformation supported by QVT

A design pattern helps to improve the quality of a software system by providing a proven solution for recurring design problems. However, the abstract and informal nature of prevailing pattern descriptions makes it difficult to use design patterns. There have been significant works on formalizing design patterns which found a base for systematic application of a design pattern. Pattern-based model transformation has emerged as an approach for incorporating pattern properties into a design model. However, the existing work mostly focuses on the solution domain of a pattern while leaving out the problem domain, structural pattern aspects with little attention to behavioral aspects, and general methodologies without concrete implementations. In this work, we present an approach for transforming an application model using both the structural and behavioral properties of a design pattern defined in terms of the problem and solution domain and its implementation using Query/View/Transformation (QVT). In the approach, we define pattern consistency for structural and behavioral pattern properties and pattern conformance for pattern applicability before transformation solution conformance after transformation. We demonstrate the approach using the Observer pattern applied to a graph application. Besides the Observer pattern, we also define transformation rules for the Visitor and Adapter patterns.