Abstract. System architectures are described in abstract terms, often using Design Patterns. Actual reuse based on such descriptions requires that each development project derive a concrete architecture from the chosen Patterns, and then implement it in code. This paper describes a case study of an industrial development project that adopted a reference application as a starting point, in order to avoid the need to design a complete architecture. Reference applications are usually made by platform or component vendors. Such applications are used to provide executable examples of best practices, for a particular platform, component set, or other technology. In this case study, the Pet Store application for the J2EE platform was chosen. Pet Store is documented by Design Patterns and is also available as source code. The development consisted of replacing the application logic, while keeping the architecture intact. The project was thus transformed from an ab initio development project in...