The TPC-App is a B2B benchmark implementing a retail scenario. This benchmark specifies a set of web services interactions to test the performance of an application server. Today B2B systems undergo a permanent technological change. There even exist competitive technologies at the same time. From a business perspective it is important that the application systems of the business partners interoperate no matter what technology is applied. In order to measure the effects of using a combination of different technologies for the same B2B scenario, we reverse engineer the TPC-App scenario into a platform independent model following the UN/CEFACT's Modeling Methodology (UMM). The resulting UMM-App benchmark defines a conceptual B2B model that may be implemented by different IT technologies in order to evaluate feasibility and performance.